Regulating the Storage, Distribution and Use of Propane and Butane

Historic PAS Report Series

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Information Report No. 25 April 1951

Regulating the Storage, Distribution and Use of Propane and Butane

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Liquefied petroleum gases (of which propane and butane are the two major varieties) are being utilized increasingly in homes, industrial plants, and in trucks, buses, and even automobiles as a source of fuel. This trend has alarmed many city and county officials who are concerned over the potential hazards of these high-octane fuels. In the early days of its history as a commercial energy source, in the late twenties, liquefied petroleum gas (sometimes referred to as LPG) was used primarily in rural areas for cooking, and occasionally for space heating, and also in certain industrial processes as a raw material. Gradually, it was learned that these gases made excellent motor fuels, and tractors and other farm machinery were converted to their use. Many trucking firms and bus companies also converted to using propane, and this trend has become even stronger in recent years.

As is true with many technological advances, or with new and potentially dangerous products, there is a tendency either to view the advance as a fearful monster, and outlaw it from the city, or to assume that the new product differs little from its predecessor, and to believe that regulations which sufficed previously will continue to operate satisfactorily for the new product. Certainly, we have seen both reactions to propane and butane. Some cities have wanted to ignore the emerging problems and regulate these fuels to areas outside the corporate limits: and still others have felt secure in the belief that their regulations for gasoline could be applied to LPG without modification.

Neither of these positions are realistic. Propane and butane are neither monsters nor are they "simply another type" of gasoline. The fire hazard potentials of LPG are greater than those of gasoline. We may, however, take comfort from the words of at least one person concerned with the danger potential of propane and butane. George Prussing, in an article in Fire Engineering reminds us that:

"We may have forgotten that the fire service went through a similar spasm of fear about illuminating gas a hundred years ago, and again about gasoline, about fifty years ago. Both have survived. LP-gas is just another of those technical changes that we shall have to learn to live with because it is so useful."1

There are, however, differences between gasoline and the liquefied petroleum gases which require special precautions and equipment in handling them. The planner will want to be aware of these in formulating his methods for dealing with the new products.

In order to approach the problem of regulation realistically, there are several things we will want to know. We will want to learn of the existing legislation and the standards which have evolved from past experience with these gases and from the considered judgment of individuals specifically concerned with the fire and explosive hazards of LPG. But, before we can understand the significance of the regulations, and before we can approach them critically, we will want to learn more about the fuels; what they are, how dangerous they are, where and how they are presently stored, transported and used, and what the future uses and problems are likely to be.

What are the Liquified Petroleum Gases?

Propane, pentane, propylene, butane (normal and isobutane), and butylene are liquefied petroleum gases obtained as by-products of the production of natural and manufactured gas by a process of absorption or compression, or a combination of these two methods. At most "natural" temperatures, they are in a gaseous state, since they boil at extremely low temperatures. For example, liquid propane boils (i.e., vaporizes) at 44 degrees F. when at atmospheric pressure. Liquid butane boils at 33 degrees F. (close to the freezing point of water!). Since they form gases so easily, in a closed container which is warmed, the liquid gases tend to expand, creating a pressure in the container. Thus, at room temperature of about 70 degrees, propane will develop a pressure of 124 pounds, and butane a pressure of about 34 pounds. If this pressure were permitted to mount above the strength of the container, explosion would result. Because of this, containers of LPG are equipped with safety valves which permit some vapor to escape when the pressure exceeds a certain level.

From these characteristics, we can see that these gases may be liquefied either by refrigeration at extremely low temperatures (which is generally not feasible) or by subjecting them to moderate pressure (the usual method employed). One of the simplest explanations of the principle involved is contained in Bulletin No. 8 of the International Association of Fire Chiefs, entitled, "Transportation and Utilization of Liquefied Petroleum Gases." The author explains:

"A liquefied petroleum gas container can be compared to a steam boiler in that both contain a boiling liquid with a vapor about the liquid developing a pressure which varies depending upon the temperature of the container. If more heat is added to a closed steam boiler, higher pressures are developed, and temperature is increased... In thinking of liquefied petroleum gases, we should have a mental picture of a gas which has been concentrated by compressing it to a liquid state for transportation and storage purposes. Only when the pressure is reduced on the liquid fuel, it reverts to a vapor and gaseous state by the absorption of atmospheric heat or applied heat from other sources."2

This reaction to heat is what gives LPG its usefulness as a fuel, but it also accounts for its hazard aspect. This is why bottled gas (propane and butane mixtures) used in homes are often covered by a sheltering canopy, and why, in some southern desert areas, propane is transferred from the storage containers to tractor fuel tanks only at night, when the temperature is lower.

Both propane and butane have high heating values (or concentrations of energy). Propane has almost 22 thousand BTU's per pound, and butane has well over 21 thousand BTU's per pound. In this, they exceed gasoline. As a motor fuel, propane has an octane count of from 100 to 130.


Opinions vary. At one extreme is the Liquefied Petroleum Gas Association, which would have us believe that they are no more dangerous than gasoline; at the other end are the cassandras of doom, who predict total destruction from them. Instead of accepting opinions, let us look at the gases themselves, their properties and characteristics, to determine their danger.

According to the National Bureau of Standards report3, the danger of explosion of liquefied petroleum gases in closed containers is no greater than that of any other confined gas, such as carbon dioxide or ammonia, for example. However, since they are normally gases and change from liquid to gaseous state so readily, they are more prone to explosion than is, say, gasoline, which is liquid in normal state. Explosion occurs when a cylinder containing a gas is heated, thus increasing the pressure of the gas against the walls of the container. Thus, if a fire should start in the vicinity of a container holding any flammable liquid, the container will explode when the temperature becomes great enough.

Explosions can also occur when the gas escapes from the container and mixes with air. This mixture must be in the "right" proportions to permit explosion. If the concentration of the gas in the air is too little or too much, fire, but not explosion, will occur. These limits are called explosive limits. Generally, the wider the range of these limits, the more chance there is that an explosion will occur; the narrower the range, the more violent will be the explosion. For propane, these explosive limits are 2.4 per cent concentration per volume of air, and 9.5 per cent; for butane, they are 1.5 and 8.6 per cent: and for gasoline, these limits are 1.3 and 6 per cent by volume of air. From this we can see that the chances that escaping gas will explode are greater for the liquefied petroleum gases than for gasoline.

An important difference between gas and LPG is that, whereas the vapor of the former is lighter than air, and therefore tends to rise, the vapor of the latter is heavier than air, and tends to settle along the ground. Thus, E. R. Weaver states in his article, "Propane, Butane and Related Fuels,"

"Petroleum gases are not poisonous, but their leakage should be guarded against even more carefully than that of manufactured gas because of fire hazard. They are heavier than air and tend to accumulate at floor level, in contrast to ordinary manufactured or natural gases, which are lighter than air and rise... A flame in the lower part of a room is more dangerous to the occupants than one of equal intensity in the upper part... These facts combine with its high heating value per unit volume to make the escape of even a little petroleum gas a serious hazard."4

This greater weight makes underground storage more dangerous for the liquefied petroleum gases than for other gases, since the vapors (if a leak should develop) tend to remain concentrated below ground, rather than to dissipate gradually into the air. In addition, underground storage makes the detection and repair of defective pipes and tanks more difficult.

One measure of hazard is the flash point of the flammable liquid which is used by formulators of standards as the basis for classifying flammable liquids. The lower the flash point of the liquid, the more stringent are the regulations of its handling and storage. The flash point of a liquid is that temperature at which it gives off a vapor sufficient to form an ignitable mixture with the air near the surface of the liquid. In the closed cup (a controlled experimental situation), gasoline reaches its flash point at 45 degrees F. Since butane and propane are gases, this point has already been reached at any normal temperature, since butane's flash point is 76 degrees, and propane's is considerably lower.

These are the intrinsic properties of the gases which constitute their potential hazards. They are due to the nature of the product — not to its use or handling. But, because of these danger potentials, the LP-gases require more careful handling than gasoline, and better, and sometimes more expensive, equipment. They require stronger and thicker walls for containers, more careful fitting of pipes, vents and safety valves, and professional installation. The consensus of opinion is that, if these extra precautions are taken, these gases will be no more hazardous than other Class I flammable liquids.


Of the yearly sales of liquefied petroleum gases, about one-half is used for domestic purposes in the form of bottled gas. Its use is most prevalent in non­urban areas where gas mains and utility lines are expensive to maintain because of the low population density, and thus, where it can compete economically with natural or manufactured gas. However, there is at least one community — St. Cloud, Minnesota — which is converting its system from the distribution of manufactured gas to that of propane through gas mains.

Where bottled gas is used, it is almost universally employed for cooking purposes. In addition, about twenty-five per cent of the users employ it for such purposes as space heating (primarily in the Southwest), water heating, and refrigeration. In 1950, this domestic consumption of LPG totaled some two billion gallons, an increase of more than 30 per cent over the previous year.

The danger involved in home use of "bottled gas" is considerable. In fact, a disproportionate number of fires which have involved these liquefied petroleum gases have occurred in home installations. There are several reasons for this poor safety record, Because of the greater danger which results from leakage, the installation of any system using propane or butane must be done with great care and proficiency, Ideally, it should be done by professional and trained personnel. Unfortunately, persons in rural areas are often accustomed to installing their own equipment and utility systems, and they have seen no reason why their amateur skills are not sufficient for the installation of bottled gas systems. This has led to the existence of many faulty pipe fittings and insecure anchorages of the tanks, which have accounted for the overwhelming majority of fires in home installations. The fires which resulted from these faulty installations have also been inordinately destructive because users of the gases live, for the most part, outside of the urban fire districts in areas which have inadequate fire protection.

Propane and butane have other rural uses in addition to their domestic use. In many areas, tractors and other farm machinery are propelled by LPG, and it is in this market that producers of the liquefied petroleum gases are most optimistic as to future expansion. Where a farmer uses propane or butane in his home and in his machinery, he generally has a special storage tank installed from which to refuel his equipment.

Propane and butane are also used in certain industrial processes. Chemical industries, which use LPG as a raw material and as solvents, bought 650 million gallons last year, which accounted for about 15 per cent of the total sales. LPG is also a raw material in the production of synthetic rubber. Other uses include its employment in refineries to produce aviation gasoline and other automotive fuels, and its use in city gas mains as a supplement to manufactured and natural gas for emergencies and peak-load requirements. Many industrial plants, in addition, use it for power, heating, and refrigeration.

The liquefied petroleum gases, when used in conjunction with industrial installations, have a fairly good safety record. Because these plants use large quantities and have heavy investments in equipment and materials, they have generally been very careful in observing rules of safety and in employing professional personnel in the installation maintenance and inspection of their installations. In some gas refineries where quantities of anywhere from 30,000 to 1,000,000 gallons may be stored, the safety record has been remarkably good. This is not to say that the installations in industrial plants and storage plants are completely hazard-free. Accidents have occurred — and the results have been serious. For example, in the Minnesota Mining and Manufacturing Company disaster where damage and inventory loss has been estimated at about one million dollars, the explosion has been blamed tentatively on a leaking butane pipeline. However, despite dramatic instances of destruction, the record has been fairly good, considering the large quantities of the gases exposed to danger.

The third major use of the LP-gases is as fuel for internal combustion engines. For many years, propane, and, to a lesser extent, butane, have been used to power farm tractors and heavy transport trucks. In 1935, experiments were made in the use of these fuels for buses, and, in that year, a company in Spokane, Washington, became one of the first to convert its equipment to burn liquefied petroleum gas. More recently, bus companies in many other cities have followed this lead, and, in addition, several taxicab fleets (in Liberal, Kansas; and Milwaukee, Wisconsin) have converted to propane. Thus far, the use of this gas in private automobiles has made little headway, however.

One of the major drawbacks to the successful use of propane as a motor fuel has been the lack of service stations at frequent intervals. Since refueling is so crucial a problem, trucks burning this fuel are generally equipped with large-capacity tanks. A long-haul truck may be equipped with a fuel tank holding 100 gallons, and, in addition, carry a spare tank of the same capacity to which his engine can be switched when the first is empty. The trucks are generally fueled at the origin, at the midpoint of a long haul (a dispensary is maintained in many cases by the trucking firm itself), and again at the destination. Because of the need to maintain one's own service stations, and because of the economy effected through ownership, it has been the larger trucking firms which have been able to take best advantage of this fuel.

Bus companies with propane-burning vehicles have also found it expedient to maintain their own service stations. These are by no means small operations. In Chicago, where the Chicago Transit Authority is replacing some 550 of their buses with propane-propelled ones, the Authority maintains two service units in conjunction with their vehicle storage yards. One of these is located on a site of 20 acres, and the other on a site of almost 30 acres both in partially vacant, industrial districts near the outskirts of the city. (Chicago has no liquefied petroleum gas code as yet, and these locations were approved by both the building and fire departments of the city.) Each bus is refueled daily, and uses about 100 gallons of the gas. Several storage tanks of 18,000-gallon capacity are located on each site and the gas is dispensed through two pumps. No structures or standing vehicles are located within 50 feet of the tanks and pumps.

At present, there are bus companies in 18 cities which have propane-equipped buses. Among them are the Capital Transportation Company in Little Rock, Arkansas, which has ordered 15 new buses, and is converting 25 more; the Kansas City Public Service Company, which has ordered 30 new buses, and is converting 114 existing ones; the Northern Transit Company in Minnesota, which has 16 propane coaches; and others in Wichita, Kansas; Omaha, Nebraska; and Spokane, Washington. The fleet of butane-propelled buses has been operating in the latter city since 1935, and has traveled some 40 million miles with an almost perfect safety record.

Some of the advantages which have been claimed for propane as a motor fuel are:

  1. Its clean-burning characteristic; it gives off no offensive exhaust fumes.
  2. The exhaust fumes have a low carbon monoxide content.
  3. The operation of the vehicles is smoother and quieter because of the slow rate of burning.
  4. The use of LP-gas eliminates vapor-lock, and thus permits the elimination of the fuel pump.
  5. It provides easier starting, and there is no spark knock which often accompanies the use of a high-octane fuel.
  6. Its use results in lower maintenance costs, because it eliminates the dilution of crankcase oil, promotes longer bearing and cylinder life, and greatly reduces carbon deposits on valves and valve stems.
  7. It has a high-octane rating.
  8. Its use results in lowered fuel costs:

The Chicago Transit Authority has estimated a saving of 2¢ a mile for their propane-burning buses. This low price has been possible because, at the present time, the supply of LPG far exceeds the demand. The price would be even lower if the costs of handling and shipping the gas could be decreased. According to the industry, prices will continue to be low in the foreseeable future, and producers are willing to make long-term price contracts with bulk users.

These advantages will continue as inducements to bus and truck companies to convert to propane. Whether these will serve as sufficient inducement to private automobile owners is still questionable.

Opinion is divided on the future of propane as an automobile fuel. The major deterrent to such use so far, in addition to the paucity of service stations, is the high cost of converting the carburetors of automobiles, a cost which is uneconomical in private use, although proven economical for commercial use in taxis. An article in the National Petroleum News in February of this year offered no encouragement to dealers planning to open propane and butane service stations. They stated in part that:

"There is one expense about which... (one)… need not worry at this time, or for some time to come. That is LP-gas dispensing equipment at service stations. All authorities agree that it is extremely doubtful that propane will ever be dispensed generally from service stations, as gasoline is today... There are a few service stations strategically located to supply cross-country trucks using propane... If the day ever arrived when trucks bought their propane regularly from service stations, they probably would have to pay as much for it as for gasoline, because of the distribution and equipment costs of handling LP-gas. This would eliminate one of the most attractive reasons for using propane.

''The possibility for use of propane by passenger automobiles is extremely remote. The motorist will have to pay around $ 250 for a special tank and carburetor to burn propane, and the average automobile won't burn enough gas during its lifetime to pay out the conversion expense. LP-gas fuel tanks will not fit on a passenger car without considerable revamping of the body, because they must be cylindrical in shape to withstand the pressure."5

It is possible, of course, that if automobiles should be manufactured for propane-use, these deterrents will no longer be so important. However, there is little prospect of this in the near future.

Despite this dark picture painted by the National Petroleum News, many communities are already being faced with the problem of what to do with the service stations within their limits. Some picture of the present extent of these stations can be obtained from a directory of propane and butane service stations compiled by the Butane-Propane News, which lists some 950 outlets, primarily in the west and southwest sections of the country. This listing is not complete, and new outlets are continually being established. Their chief patrons are heavy-haul trucks, of which there are an estimated 2,500 using propane or butane on the West Coast alone.

These service stations are not always maintained independently. More often than not, they are a subsidiary of a larger operation — either of a bulk storage and/or bottling plant, or of a service station supplying conventional motor fuels as well. This makes the regulation of this one aspect difficult without a consideration of the locational requirements, not only of the service station, but of the other operations of which it may be but a part.

These, then, are the present and potential areas of propane and butane use. It is fairly safe to predict that the total annual sales of these gases will continue to increase. From a total sales volume of 141,505,000 gallons in 1939, of which about half was used in industrial and chemical processes and under 30 per cent as a domestic fuel, the propane and butane market had expanded to 2,658,949,000 gallons in 1949, and 3,333,000,000 gallons in 1950, with domestic uses playing a more important role in the total distribution.

We can reasonably expect that this increase will continue, but the rate of increase will depend upon several variables. The most important of these is the relative price of LPG compared to the prices of competing sources of energy, such as natural and manufactured gas and gasoline. At present, it does not pay producers of liquefied petroleum gases to ship and store more than about one-fifth of the total annual production of these gases since transportation and storage costs are high and the demand for the gases is limited. Thus, about four-fifths of the product is burned off at the source. Should other fuel prices rise due to scarcity (as could occur in a wartime economy), we would expect a greater substitution of the non-scarce LPG in many areas where conventional fuels are presently used. Another factor which would increase the use of LPG would be a reduction in the cost of transporting and storing the gases, making possible a lower price.


Liquefied petroleum gases are transported both in tank cars and tank-­trailer trucks. The former are constructed in accordance with specifications established by the Interstate Commerce Commission, which also has established rules for LPG-containers of other types. The latter are of greater concern to city officials. Because they move about on city streets, park and unload in various parts of the city, they bring their danger with them, as it were. Some cities, in Kansas especially, have attempted to minimize this hazard by requiring trucks transporting flammable liquids to travel on specified routes, generally in the sparsely-settled sections of the city. Other cities have regulations prohibiting trucks carrying these liquids from traveling through the city. These solutions are proving inadequate, and will become even less feasible as the number of service stations increases, and their distribution is less confined to the major truck highways on the outskirts of cities. Should the dispensing of LPG ever become as extensive as that of gasoline, these "negative" controls will prove even more unrealistic.

There are no accident records available for trucks transporting liquefied petroleum gases alone, but we may infer these from the accident figures for all tank trucks carrying flammable liquids. These figures reveal that about 65 per cent of the fires which do occur in these vehicles occur while the trucks are in motion. The greatest danger here is from collision of the tank trucks with other vehicles (19.5 per cent of the accidents involving such collisions), with trains (13 per cent), and with buildings, trees, poles, etc. (11.7 per cent). Another 10 per cent involved overturn or blowout. Only 2 per cent of the accidents involved a spillage of the flammable liquids.

The greatest number of accidents involving standing vehicles occurred at the points of loading and unloading at storage plants. Fourteen per cent of all accidents involving tank trucks occurred while loading at bulk storage plants, and another 8.7 per cent occurred while unloading at filling stations. Actual figures for LPG trucks would probably reveal a higher percentage of fires at bulk storage stations, and a lower one at service stations, simply because of the relatively small number of such stations.

The danger potential of tank trucks transporting LPG is greater than that of most other flammable liquid-transport trucks, according to Roi Woolley. In his article entitled, "Street Transportation Hazards of Flammable Liquids — Part I," which appeared in Fire Engineering, August, 1948, he states:

"Transportation of gasoline is dangerous enough under even most ideal conditions, but it doesn't compare for deadliness with liquefied petroleum gases, such as propane, butane and related mixtures.

"In spite of efforts by producers and handlers of LPG products to follow the best safety practices, there have been a number of serious accidents involving operation of LPG transports, and some of these have occurred within the limits of cities."6

He cites one case, the Oklahoma City disaster in 1944, where a truck carrying propane and butane caught fire and later exploded, causing the death of five persons, the injury of 21, and a property damage of $60,000. This truck had been duly inspected and licensed, and was following the special route designated by the city for trucks carrying flammable liquids. Thus, we see that, despite the precautions taken, danger still exists.

Another important fact which Mr. Woolley points out is that the danger of the tank-truck is not related necessarily to its size. Many cities, again in Kansas, primarily, passed ordinances in the thirties to prohibit trucks carrying flammable liquids in excess of 600 gallons from the city. The wisdom of this is questionable. While it is true that, should a fire occur, the damage will be greater if more fuel is involved, the safety record for the larger carrier is generally better than that for the smaller, since greater safety precautions are usually taken on the larger trucks.


The lack of storage facilities in the liquefied petroleum gas industry is serious. Since the gases must be stored under continual pressure and in containers of more than average strength, a bulk storage plant is extremely expensive. The search for cheaper methods of storage has led to the suggestion that abandoned salt mines be adapted for storage purposes, but this possibility is limited by the location of these mines. At present, the practice is to store the liquids in metal containers equipped with safety valves, either above or below ground. A storage plant of average quality, having a 30,000-gallon capacity, requires an investment of approximately $22,560, according to an article in the National Petroleum News on February 14, 1951.7 The storage tank with the manhole ladder and platform costs $7,500. Other expensive items are the compressing machinery, and the equipment required to make transfers from and to transport trucks. Pipes, pipefittings and labor for installation is estimated at an additional several thousand dollars. Estimates of the expense, given in an early volume of the National Petroleum News,8 set the cost of a 30,000-gallon tank completely installed at $9,000, and the compressor and truck loading equipment at an additional $6,000.

If this is the cost of so small an installation, one can see that a bulk storage plant of a million gallons or more involves a rather heavy investment. And, if one considers that the storage plant may be but a part of a more extensive installations of large liquefied petroleum gas companies, one realizes that once located, such a plant will be difficult to eliminate as a nonconforming use. Regulation and zoning must be instituted before storage plants are established.

Again, we must emphasize that these bulk storage plants are maintained frequently in conjunction with other operations of the industry. For example, a gas refinery producing LPG may have storage plants, bottling equipment and distribution facilities on the same location. It may even maintain a service station on the site. Jobbers retailing bottled gas may store large quantities for truck fueling as well, and service stations may bulk-store several thousand gallons on the premises.


Most states and municipalities have some provision for regulating the fire hazards of flammable liquids. These are generally oriented toward the safe storage, handling and use of them. In addition, regulations have also been imposed on the transportation of these flammable liquids. With the growing popularity of the liquefied petroleum gases, some states and municipalities have simply extended their flammable liquid codes so as to include the regulating of LPG. In these, the administrator (the city or state fire marshall, or some other deputized official), is given the additional responsibility of setting up standards for LPG regulation. There are other states, however, which, either lacking in such general legislation, or sensing the inadequacy of the existing legislation have established specific laws applying to LPG.

Practically every state has some legislation authorizing the establishment of standards for, and regulations of, the liquefied petroleum gases. Maine, Kansas, Kentucky, Michigan, Indiana, Minnesota, New Hampshire, North Dakota, Tennessee and Vermont, among others, have state legislation covering a somewhat broader field than LPG — either flammable liquids, combustibles, or simply fire hazards. In these states, the State Fire Marshall or the Insurance Commissioner, or a state department of some kind (either labor or public safety, etc.), is authorized to establish standards and regulations for fire hazards, among which are the liquefied petroleum gases.

More recently, there has been a trend toward the passing of special liquefied petroleum gas legislation. In most cases, the guide for such legislation has been the model law suggested by the Liquefied Petroleum Gas Association. Such states as Missouri, New Jersey, North Carolina, South Dakota, South Carolina, Oklahoma, Virginia, have incorporated this suggested model into the state enabling legislation.

Municipalities have also instituted regulations, either in lieu of adequate state laws, or as supplementary to them. Some of these ordinances have followed the model suggested by the National Board of Fire Underwriters in Part 8 of the Suggested Fire Prevention Ordinance, dealing with the ''Compressed and Liquefied Flammable Gases Other Than Acetylene." This model ordinance incorporates the standards of not only the National Board of Fire Underwriters, but those of the American Petroleum Institute and the American Society of Mechanical Engineers. Another model ordinance, which has been put forward by the Liquefied Petroleum Gas Association, authorizes the adoption of regulations in conformity with state regulations, or, where such are lacking, authorizes the adoption of the standards of the National Board of Fire Underwriters as recommended by the National Fire Protection Association in Pamphlet 58.


It might be well, at this point, to explain the background of Pamphlet 58. This pamphlet contains a set of standards which have had the most far-reaching influence on both state legislation and municipal ordinances. These standards form the basis, if not the sum total, of the regulatory laws of over twenty states. Even where specific LPG legislation is lacking, the administrator, entrusted with the regulation of flammable liquids for fire protection, has looked for guidance on LPG to this, by now famous, Pamphlet 58.

Pamphlet 58 is the result of collaborative efforts of the National Fire Protection Association and the National Board of Fire Underwriters, and has received the endorsement of many groups, including the Liquefied Petroleum Gas Association. Copies of this pamphlet may be obtained by mailing the coupon attached at the end of this bulletin to the National Board of Fire Underwriters.

The NBFU and NFPA would be the last to claim that these regulations, or standards, as they prefer to call them, are the final authority on the subject. Too little is known about these gases to permit an authoritative set of regulations, and the standards promulgated by these organizations undergo constant revision in the light of increased knowledge and experience with the gases.

The National Fire Protection Association first established regulatory standards for liquefied petroleum gases in 1927. These regulations applied only to above­ground installations using cylinders or drums. Later, as the uses were extended, the first draft of Pamphlet 58, entitled, "Standards for the Design, Installation and Construction of Containers and Pertinent Equipment for the Storage and Handling of Liquefied Petroleum Gases," was published in 1932. In succeeding years, as new problems have arisen and as uses have changed, these standards have been revised and expanded. A complete revision was made and published in 1947, and it is this edition which forms the basis for practically all state and municipal regulations. Since that time, however, revisions and additions have been made. In 1949, a new edition of Pamphlet 58 was adopted by the NFPA and the NBFU. This was amended again in 1950, to include a section on the fueling of tank-trucks and tank-trailers in trailer camps.

One of the major deficiencies of Pamphlet 58, even in its most recently revised form, is the omission of standards for service stations dispensing LPG gases. Provisions for this were included in the standards submitted to the National Fire Protection Association Convention in 1950, but no agreement could be reached on them. According to the Chairman of the NFPA Committee on Gases, Mr. H. E. Newell, this problem is on the docket for consideration by the Committee some time next year, but early action on it does not seem likely.

Although Pamphlet 58 is, perhaps, the most complete and thoughtful set of standards available, one should not be misguided into the belief that, with the adoption of these standards, a community has solved all of the problems which may arise from these gases. Not only are these regulations subject to change, and in need of certain general additions, but also, Pamphlet 58 is concerned primarily with the regulation of the technical or engineering aspects of equipment, and there is little in it which can serve as a specific guide to city planners wishing to regulate the location of various installations using LPG.

Briefly, the standards in Pamphlet 58 may be summarized as follows: The regulations are divided into "Basic Rules" applying to liquefied petroleum gas and to the systems utilizing it, and the specific rules oriented toward the various points of handling of the gases. Among the general rules are those which require that all liquefied petroleum gases be odorized, that systems be duly tested by the Underwriters' Laboratory, or some other nationally-recognized laboratory, and that in installations utilizing storage containers of over 1,200 gallon-capacity, plans shall be submitted to the administrator for approval. Other basic rules prescribe standards for safety valves, filling densities, and transfers of the gas.

Besides the provision that someone must be in attendance while transfers of gas are made, there are also some general statements as to the location of tank-truck unloading points. These, Pamphlet 58 states, should be located with due reference to the following:

  1. Proximity to railroad and highway traffic.
  2. Distance to adjacent property.
  3. Distance to buildings on the site.
  4. Nature of occupancy of the site.
  5. Topography.
  6. The type of construction of buildings and other equipment.
  7. Number of tank trucks which can be safely unloaded at one time.
  8. The frequency of such unloadings.

Standards are also established for electrical connections, distance to open fires, and between bulk storage tanks both above and below ground.

After these basic rules are presented, the pamphlet is divided into seven sections, each dealing with a specific type of installation. These cover cylinder systems or bottled gas, the regulation of containers other than those prescribed by the ICC, safety regulations for tank-trucks and semi-trailer-trucks transporting LPG, the use of LPG as a motor fuel, and its attendant safety devices, problems of storage at points other than that of final utilization, and cylinder systems for cooking and heating on highway motor vehicles, i.e., trailers.

In addition to Pamphlet 58, the National Board of Fire Underwriters publishes several other suggested standards which are relevant for the regulation of liquefied petroleum gases. For example, Pamphlet 59 is concerned with the regulation of "Liquefied Petroleum Gases at Utility Gas Plants," and Pamphlet 30 deals with "Standards... for the Installation of Containers for Storing and Handling Flammable Liquids." A complete listing of relevant publications by the NBFU may be obtained from their office (85 John Street, New York).

Other standards have been promulgated by the Liquefied Petroleum Gas Association, which has published "Recommended Good Practices for Liquefied Petroleum Gas Piping and Appliance Installations in Buildings," and by the American Petroleum Institute and the American Society of Mechanical Engineers. The latter two have concentrated on the determination of standards primarily for containers of LPG — the container strength, safety valve devices, filling densities, etc. The Interstate Commerce Commission has also adopted standards for containers of LPG.


Practically every state LPG law either accepts the standards of Pamphlet 58 in toto, or in an only slightly modified form. Some codes may add a section or two, or may vary some of the wording, but basically the standards accepted are the same as those in Pamphlet 58. However, in addition to these regulations, some states have sought to further supervise the safety of LPG storage handling and installation, by requiring inspection, licensing, bonding, and/or special permits. For example, the states of Massachusetts, Kentucky, Alabama, Arkansas, Florida, Georgia, Minnesota, Mississippi, New Mexico, Michigan, Oklahoma, and Texas all require the issuance of a permit or license, some only for operators of large-scale bulk storage. but others for all dealers and handlers of LPG, including jobbers, installers, storers, and shippers of the gases. In some other states, the granting of such permits is contingent upon inspection of the facilities. Usually, a fee is charged for the license or permit, which may vary anywhere from a few dollars (with additional inspection charges if inspections are to be made) to $100 (Alabama and Georgia) for a yearly permit to engage in the distribution, manufacture, sale, storage, transport, installation, repair or servicing of LPG or its equipment. Some states, such as Florida and New Mexico, have sliding permit charges, depending upon the particular operation. In Florida, annual licenses are required, for which manufacturers of appliances or equipment and dealers in LPG equipment, appliances and installation pay $35 a year. Dealers in LP-gas alone pay $20, installers pay $15, and dealers in appliances and equipment alone pay only $10.

Another method whereby states have attempted to control the reliability of handlers of the gases is through bonding or insurance requirements. Georgia, Mississippi, New Mexico, Alabama, Arkansas, Florida, and Oklahoma are some of the states with these requirements. Bonding may range anywhere from $5,000 to $25,000.

In addition to these enforcement provisions, some states require the inspection of installations, especially of large bulk-storage installations and have established a fine for violators of the LPG legislation. Although in many states, the regulations are not retroactive — i.e., do not apply to installations already in operation — a few states require all installations to conform to the standards established. Texas has an interesting requirement which provides that inspection must be made of containers during their fabrication, and inspection must be made of any installations involving flammable liquids in public buildings or buildings to which the general public is invited. The regulations also require the testing of relief valves on bulk storage every five years, on transports every three years, of excess flow valves on bulk storage and transports every three months. This reinspection process is particularly important, since, as the equipment gets older, danger is generally increased because of the continued pressure on the container walls and the deterioration of the relief-valve system.

Many municipalities have ordinances regulating LP-gas. A partial list of these, compiled by the Liquefied Petroleum Gas Association, enumerates some 158 municipalities in 34 states. Among the larger of these cities are: Montgomery, Alabama; Los Angeles, Sacramento, and San Francisco, California; Colorado Springs, Colorado; Hartford, Connecticut; Wilmington, Delaware; 23 municipalities in Florida, including Miami, Miami Beach, Tampa, and St. Augustine; Atlanta and Savannah, Georgia; Des Moines, Iowa; Wichita, Kansas; Baltimore, Maryland; Detroit and Muskegon, Michigan; Minneapolis and St. Paul, Minnesota; Kansas City, Missouri; Reno, Nevada; Albuquerque, New Mexico; New York City, New York; Akron, Cincinnati, Cleveland, Columbus, Cuyahoga Heights, Dayton, and Toledo, Ohio; Oklahoma City, Oklahoma; Charleston, South Carolina; Memphis, Tennessee; 25 towns and cities in Texas, including Dallas, El Paso, Ft. Worth, Galveston, Houston, etc.; Salt Lake City, Utah; Richmond and Arlington County, Virginia; and Seattle, Spokane, and Tacoma, Washington.9

These ordinances are, again, oriented primarily toward the enforcement of certain minimum safety standards of equipment. Only occasionally is a reference made to the locational, in terms of the general city pattern, aspects of storage and distribution of liquefied petroleum gases.


Little guidance in regulating the location of LPG installations can be obtained from Pamphlet 58. Its sole statement on the matter reads as follows:

"In cases of bulk storage in heavily populated or congested districts, the inspection department having jurisdiction shall determine restrictions of... distance to line of adjoining property, which may be built on and other reasonable protection methods...

"Where the storage exceeds 10,000 pounds of gas at one storage location, such storage shall be located at least 25 feet from important buildings or regularly busy main thoroughfares."

A few of the state and municipal regulations are more specific on this point. In the code of Kentucky the provision is made that, except where approved containers conforming to the Kentucky Commerce Regulations are used, aboveground storage containers shall not be located inside the fire limits of the city, and if these containers have a water capacity of over 500 gallons, shall not be located elsewhere within the corporate limits of the city or town. It further provides that underground storage containers in excess of 500 gallons shall not be located within the fire limits at all, regardless of the type of installation. Wisconsin and Michigan are two other states which prohibit underground storage for bulk quantities of the gases.

Many codes specify the distances to property lines, streets and alleys, and built-upon property which must be maintained from bulk storage installations. These regulations touch only superficially the problem of general location. The section of the Kentucky code which deals with this problem contains the following specifications:

"Section 1905: The Location of Containers and Regulating Equipment:


(c) Loading or distributing stations, and aboveground storage containers, except approved containers conforming to Kentucky Commerce Regulations (K.C.C.), whether inside or outside the corporate limits of a city or town, shall not be permitted in congested areas or in built-up neighborhoods primarily of a dwelling character, when the installation of such containers would constitute a serious threat to the safety of life and property in such areas or neighborhoods.

Loading or distributing stations involving the transfer of liquids into portable containers of any type, shall not be permitted within the fire limits. Where transfer of liquid is made from containers used in domestic or commercial service into portable containers, such as on tractors, skid-tanks, or similar applications, such containers shall be located not less than 50 feet from the nearest building, and 25 feet from the nearest public thoroughfare."

The State of Michigan, in its fire hazards law, requires that a map for the area within 500 feet of any installation be submitted prior to granting of a permit. This law also specifies that where containers have a capacity of over 1,200 gallons, they must be located 150 feet from the adjoining property line. The Michigan code also provides that in the case of storage for resale and retail outlets:

"(a) Containers may not be stored within 500 feet of a school, church, hospital, athletic field and other points of public gathering,

(b) Where the storage exceeds 1,000 pounds of gas in one location, it must be located at least 50 feet from buildings, property lines, streets, alleys and highways ..."

In the case of filling or bottling plants, it requires that:

"(a) The pump house, if any, must be located not less than 10 feet from the bulk storage tanks, and not less than 50 feet from the property line.

(b) The cylinder filling room must be located not less than 25 feet from the bulk storage tanks, 10 feet from the pump house, if any, and not less than 50 feet from the property line."


In addition to the regulations presented in the above section, there is little material available on recommended practices of location which would be suitable for inclusion in a zoning ordinance. Generally, it is recognized that bulk storage plants should not be permitted in heavily-populated or congested districts, and that the storage should not be close to places of assembly or to residential areas.

For example, the Detroit ordinance requires that bulk storage (which is defined as storage in vessels over 60-gallon capacity) be limited as follows:

"No storage tank shall hereafter be erected less than 300 feet from any mine shaft, air or escape shaft from any mine, any school, church, hospital, theater or public hall, a public hall being any place that is regularly used by the public for meetings or assembly for amusement, instruction or religious worship."

Zoning ordinances, as yet, have not differentiated between the storage of propane and other petroleum products. In many of these ordinances, bulk storage of petroleum products is permitted only in the heavy industrial district. For example. the recent Norfolk, Virginia, ordinance restricts wholesale storage of petroleum and petroleum products to the heavy manufacturing district. The Pittsburgh, Pennsylvania, ordinance prohibits gas storage in excess of 10,000 cubic feet in its light industrial district. Ft. Worth, Texas, also restricts wholesale storage to the heavy industrial district. The same is true for Los Angeles, California, and Denver, Colorado.

In Baltimore County. Maryland, the zoning regulations (1948) require that:

"In either a commercial or light industrial zone, a special permit shall be required for the storage of fuel oil and other petroleum products for distribution or for sale at either wholesale or retail. Such storage shall be in underground tanks, except that the zoning commissioner, or the Board of Zoning Appeals, upon appeal, may authorize storage in tanks above ground where the public health and safety will not be adversely affected thereby."


Cities have attempted to control the dangers involved in transporting of liquefied petroleum gases through the enforcement standards such as those described in Pamphlet 58. They have also attempted to minimize the hazards of transport trucks by restricting their movement through certain sections of the city. For example, a number of cities restrict trucks transporting propane, butane, or other flammable liquids to certain specified truck routes. These cities include Burlington, Iowa; Portland, Oregon; Denver, Colorado; and Mobile, Alabama. In addition to restricting trucks to certain routes, many cities have also passed ordinances preventing trucks carrying in excess of a certain volume of flammable liquids from using the city streets. A number of cities in Kansas passed ordinances of this nature in the thirties. The City of Newton, Kansas, ordinance "Regulating the Transportation of Gasoline or Any Other Inflammable or Explosive Substance into or through the City of Newton, and Providing a Penalty for the Violation Thereof" reads as follows:

"Section 1. That hereafter it shall be unlawful for any person, firm or corporation to transport, haul, or carry any gasoline or inflammable or explosive gas fluid or substance in a truck, transport or trailer within the city limits of said city, in larger quantities than 600 gallons in any one truck, transport or trailer."


Cities have also sought to regulate the location and safety standards of service stations, but, as in zoning ordinances with relation to bulk storage, they have as yet made little distinction between gasoline service stations and those dispensing propane and butane. This is, perhaps, the most important and controversial issue in propane-butane regulations. No standards have been established, nor has there been any adequate solution to the problem of location. Thus far, the problem has not been too serious, since the service stations dispensing these fuels have been maintained in conjunction with bulk storage or refinery plants (which have generally been permitted only in heavy industrial districts), or have been located on major truck routes on the outskirts of town or beyond the city limits. However, if propane and butane are used for private automobiles, service stations will require locations throughout the city. This eventuality increases the problems of regulation.

The Indiana Flammable Liquids Code contains some fairly typical provisions for gasoline service stations. Particularly significant in these regulations are the rules concerning the placement of storage tanks with relation to surrounding buildings and property lines. Section 5 reads as follows:

"5. Clearance Required:

(a) To Basements, Etc. Individual tanks of a capacity up to 3,000 gallons shall be buried so that tops of tanks shall be lower than all floors, basements, cellars or pits of buildings within 10 feet, on or off the property, or tanks shall maintain a full clearance of 10 feet thereto. For individual tanks a capacity of 3,001 gallons and up to 5,000 gallons in one individual tank, the distance shall be 20 feet.

(b) To Sewers, Etc. Individual tanks of a capacity up to 3,000 gallons shall be buried so that tops of tanks shall be lower than the bottom level of all sewers, manholes, catch-basins, cesspools, septic tanks, well or cisterns within 10 feet, on or off the property, or tanks shall maintain a full clearance of 10 feet thereto. For individual tanks of a capacity of 3,001 gallons and up to 5,000 gallons in one individual tank, the distance shall be 20 feet. The term "sewer" includes sewer line out of station building.

(c) To Property Lines. Individual tanks up to and including 3,000 gallons capacity shall maintain a 10-foot clearance to all property lines, either public or private, and the State Highway right-of-way line. Individual tanks greater than 3,000 gallons capacity, up to and including 5,000 gallons capacity shall maintain a clearance of 20 feet. No individual tank for underground storage of Class 1, 2 or 3 liquids at a service station shall be larger than 5,000 gallons capacity.

(d) To Special Classes of Property. Tanks and pumps shall maintain a clearance of not less than 300 feet to any mine shaft, air or escape shaft for any mine, and 85 feet to any schoolhouse, hospital, church, public hall, place of assembly, theater, motion picture show, hotel, lodging house, city village or town hall, fire station, light or power station, commercial gas tank, factory or dry cleaning plant. The distance shall be measured from near points of tanks and pumps to near points of buildings or shafts."

Although this set of regulations has been presented here, it is not to be taken as a model for the regulation of propane and butane-dispensing service stations. It is offered simply as one example of the type of regulations which will have to be devised — but standards suitable to propane and butane must be evolved independently.


We have seen how the increasing use of propane and butane has led to many municipal problems for which an adequate and complete solution is yet to be found. Some excellent starts have been made. The latest edition of Pamphlet 58 shows a remarkable advance over the original edition of 1932. In addition, we have other standards to guide us — such as those of the I.C.C., the A.P.I., and the A.F.M.E.

However, although there is a great deal to be said for the desirability of uniformity, the complete acceptance of these standards does not offer a panacea for all LPG problems. This is true not only because Pamphlet 58 and the other standards are tentative and subject to revision, but also because they still leave many areas of control unregulated. We would close with the admonition that, although these standards are the best available at the present time, they leave much to be desired. They also leave an opportunity for city planning officials to study the problems involved and to make a contribution to the regulation of the liquefied petroleum gases.


1. George F. Prussing, "L.P. Gas — What Fire Hazards?" in Fire Engineering, May, 1950.

2. O. L. Garretson, "Transportation and Utilization of Liquefied Petroleum Gases," in Educational Bulletin No. 8, July, 1941, (published by the International Association of Fire Chiefs, 24 West 40th Street, New York).

3. E. R. Weaver, "Propane, Butane and Related Fuels," Circular of the National Bureau of Standards C420, United States Department of Commerce, (Government Printing Office, Washington: 1938), 21 pp.

4. Ibid., page 4.

5. Leonard Castle, "LP-Gas as a Motor Fuel," in National Petroleum News, February 14, 1951, pp. 56, 59–62.

6. Roi B. Woolley, "Street Transportation Hazards of Flammable Liquids, " Part I in Fire Engineering, August, 1948, p. 511.

7. Leonard Castle, op. cit.

8. "LPG Marketing," in National Petroleum News, July 16, 1947, pp. 28–36.

9. Liquefied Petroleum Gas Association, Legislative Data, LPG Manual, pp. 83–84. (Liquefied Petroleum Gas Association, Chicago Office: 11 South LaSalle Street, Chicago, Illinois.)

Copyright, American Society of Planning Officials, April, 1951.

National Board of Fire Underwriters

85 John Street

New York 7, New York

Dear Sirs:


I have been referred to you by the PLANNING ADVISORY SERVICE which, in a recent bulletin, mentioned the availability of this pamphlet.




June 1, 1951

American Society of Planning Officials

1313 East 60th Street Chicago 37, Illinois

ATTENTION: Miss Janet Lippman


As discussed in our telephone conversation with Miss Lippman, we appreciate the opportunity of submitting comments on Information Report No. 25 in the Planning Advisory Service of the American Society of Planning Officials. This report is entitled "Regulating The Storage, Distribution and Use of Propane and Butane." While this report is fair and complete insofar as reporting legislative developments, we feel that there are certain statements concerning the nature of the product that are capable of misconstruction. We are certain that this was not your intent, and would like to comment on the portions of the report we believed inaccurate.

We want to emphasize that we appreciate your very apparent effort to be judiciously fair in treating of hazards of LP-Gas. However, through this effort and in comparisons made you have given the hazards a type of negative treatment that could be misleading to a planning official completely unacquainted with the industry.

We feel it unfortunate that you attempted to make a comparison between LP-Gas and gasoline and stated that LP-Gas presents a greater fire hazard and is more prone to explosion. While they are both petroleum products and in one or two instances used for the same purposes, the similarity ends there. While it is true that you state there are differences between the products requiring different handling, you nevertheless go on to make hazard comparisons. The inherent nature of the products and the difference in the method of handling, make it unfair to either one, to compare everyday hazards with the other without complete qualification. However, in view of the fact that you have undertaken to do so and quote various persons on the subject, permit us to present the case for LP-Gas. We would like to quote from a decision of the Interstate Commerce Commission given on July 8, 1948 in Docket No. 5440. The ICC was required to compare respective hazards in connection with rate making and we emphasize that this statement is based on voluminous evidence before it.

"Both liquefied petroleum gas and gasoline are inflammable, but the former is inherently more hazardous. Upon escape from a container it vaporizes immediately and creates a fire hazard in the vicinity that is overcome only by dissipation in the air. Gasoline is relatively slow to vaporize but the liquid flows into depressions where it remains and is frequently the cause of accidents. Losses in the transportation of liquefied petroleum gas have been negligible. This has been due to precautions taken in the handling of the commodity and the special construction of the cars that are used. Tanks have remained intact in railroad wrecks when other types of cars were demolished. There is no record of a tank having been punctured so as to permit release of the gas. Cars used for the transportation of gasoline are of less sturdy construction. A liquefied petroleum gas car costs more than twice as much as a gasoline car, and the rental paid by the shipper to the car owner on the former is more than twice that on the latter. The liquefied petroleum gas cars are furnished by the shippers, who receive an allowance from the railroads at the rate of 1.5 cents a mile, the same as made on other tank cars. Therefore to a large extent at least the expense of making liquefied petroleum gas safe for transportation is being borne by the shippers. It is clear that from the standpoint of hazard alone there is no justification for higher rates on liquefied petroleum gas than on gasoline."

In this same case, we would also like to quote from the testimony of a recognized authority, Mr. H. A. Campbell, Chief Engineer, Bureau of Explosives, American Association of Railroads, placed on the stand as an adverse witness.

"There is certainly less hazard in the transportation of liquefied petroleum gas in a liquefied petroleum gas car than there is hazard in the transporting of gasoline in a gasoline car."

LP-Gas truck transports are similarly constructed of thick walled high strength steel and a conclusion as to comparative transportation hazards based on the factual evidence of this case would be much fairer. We also note in the report you refer to one or two specific accidents. Contrariwise we could refer to the transport accident records of both fuels in the Chicago area over the past year or so. The only accident concerning an LP-Gas transport we note states that while the truck chassis was seriously damaged in an accident, the tank itself was undamaged and was transported to its destination without the loss of any gas. We are sure that you would find this true in the vast majority of highway accidents involving LP-Gas transports. The construction of the container makes these transport tanks much less subject to damage in an accident.

We regret that you dismiss so lightly the opinion of LPGA that LP-­Gas is no more dangerous than gasoline without a thorough check into the basis for this statement. In the interest of accuracy, we emphasize that this opinion has reference only to those stages of handling or operations where a basis for comparison exists, largely with reference to use as a motor fuel. As stated before, there is generally no basis for comparison in other uses. Our comments on other items contained in the report appear in the attachment. We hope that you will appreciate the difficult position the report may place the LP-Gas industry in. Because of its authoritative source, it will unquestionably be used by planning officials. We strongly feel that the inference contained in this report will serve to prejudice the planning official in his handling of LP-Gas ordinances.

Consequently, we urgently request a correction of this report. As initially offered, we not only will be happy but appreciative of an opportunity to comment upon future reports, before they are issued, to the end that the utmost accuracy will be contained in reports of the stature issued by the American Society of Planning Officials.

Very truly yours,





1. On page 2 consideration is given to the pressures. In this connection we would also like to point out that containers for LP-Gas are constructed with a factor of safety of 4 or 5 to 1. To adequately portray the picture this should have been mentioned. The safety valves mentioned would prevent an explosion through permitting vapor to escape long before the limits of this factor of safety were reached.

2. Again on page 2, emphasis is placed in stating that these gases may be liquefied by refrigeration at extremely low temperatures. Butane liquefies at 33° F. We do not believe that this could be considered an extremely low temperature. The use of the term "extremely" places undue emphasis on the temperatures involved and may conceivably build up an uncalled for hazard in the minds of the readers.

3. On page 3 the statement is made that bottled gas systems are often covered by a sheltering canopy because of reaction to heat. That is completely erroneous. The sheltering canopy is intended to prevent tampering with the regulators and valves on top of the bottled gas cylinders and has no relationship to temperature.

4. In this same paragraph on page 3, the statement is made that in some desert areas propane is transferred from the storage containers only at night when the temperature is lower. We would appreciate receiving the basis for this statement. It is something that we have never encountered.

5. On this same page 3, it is stated that if a fire should start in the vicinity of a container holding any flammable liquid, the container will explode when the temperature becomes great enough. This creates an unfair implication through omitting the qualification that such action will not occur where the container is equipped with a safety relief valve, as they are for liquefied petroleum gas.

6. On page 4, much emphasis is placed on the fact that LP-Gas is heavier than air and may tend to accumulate. This theory has undergone a change as the result of actual experiments at Underwriters Laboratories as a result of which the Board of Fire Underwriters now state they make no distinction between manufactured, natural and liquefied petroleum gas for this reason. Liquefied petroleum gas is subject to the same laws of diffusion as all gas and will dissipate rapidly. Bearing out this statement is Bulletin No. 285 of the National Board of Fire Underwriters a copy of which is enclosed. Also note the quote from the ICC case on this point in comparing LP-Gas with gasoline.

7. On this same page 4, it is stated that the underground storage makes detection and repair of defective pipes and tanks more difficult. If this is true then in comparisons with gasoline would that not make gasoline more hazardous, in view of the thinner walled tank and weaker piping.

8. On page 5 one community is mentioned as converting its system from this distribution of manufactured gas to that of propane through gas mains. This is not uncommon and there are a great many communities that do so.

9. Further on page 5, the statement is made that a disproportionate number of fires which involve LP-Gas have occurred in home installations. We would appreciate receiving information as to any statistical basis for this statement, as well as the following statements in the same paragraph. We believe that these statements are not borne out by the records but are merely the result of conjecture based on theoretical hazards however unfounded. As such, they should not be reported in such a factual manner that would lead to their acceptance by a planning official without question or further investigation.

We consider our industry's safety record to be at least equal to that of any other fuel used for the same purposes. It should be borne in mind that there are over 7-1/2 million families served by this industry. The only statistical information on fire losses that we are aware of is that contained in the annual NFPA report of fire losses. On that list you will find gas, which also includes "city gas", in 15th place — well under other fuels.

10. On page 9, it is stated that 4/5 of the liquefied petroleum gas is burned off at the source. This is a misstatement. It is possible that the statement arose out of confusion as to the method of production at refineries. Refineries can produce more or less at will and the product may vary substantially from day to day. The burning off of the product as depict in this statement would be prevented by production regulations of the State of Texas where much of the product is produced.

11. On this same page 9, the statement is made that while no accident records are available for trucks transporting LP-Gas you infer these from the accident figures for all tank trucks containing flammable liquids. Such an inference is completely erroneous and may have led into other conclusions objected to. It does not take into consideration that trucks transporting LP-Gas have a thicker and stronger walled tank, and better equipment as you concede in other sections of the report. The use of this equipment does not permit an inference based on the record of all tank trucks. Possibly you made this statement on the basis of the article by Mr. Woley quoted on page 10. Mr. Woley apparently does not take into consideration in this article the stronger liquefied petroleum gas containers and equipment. We again refer to the findings of the ICC mentioned in the covering letter.

12. We consider any hazard comparison with gasoline as a basis ill advised. Our comments on this are contained in the covering letter in view of the fact that this theme reoccurs throughout the report.

F. P. File C48

National Board of Fire Underwriters


Revised September 25, 1950

Special Interest Bulletin No. 285

Gas Appliances — Location

There has been a considerable amount of discussion in the past few years regarding the proper location of gas burning appliances. Whether the density of a fuel gas is a controlling factor in determining if an appliance should be installed in a basement or other below ground level location has been debated pro and con.

The National Board of Fire Underwriters has reviewed this entire subject and concluded that the evidence — theoretical and experimental — and the experience record, as well as practical considerations, do not justify making a distinction with regard to the location of appliances burning natural gas, liquefied petroleum gas, manufactured gas or city gas. All gas burning appliances should be installed with the following factors taken care of:

  1. Sufficient ventilation to afford air for complete combustion,
  2. Adequate means for disposal of the products of combustion,
  3. Windows, doors or other openings leading to the space where the appliance is located so that any inadvertently escaped unburned gas can be disposed of by natural ventilation,
  4. The appliance should meet the requirements of a nationally recognized testing agency (such as Underwriters' Laboratories, Inc. or the American Gas Association, Inc., Laboratories) which is adequately equipped and competent to perform such services; the agency's listing of the appliance should be evidenced by the attachment of its seal or label. Appliances approved by the above agencies for LP-Gas have safety pilots of the 100 per cent shutoff type. Appliances­ converted to LP-Gas should be checked to see that a 100 per cent safety pilot has been installed.

Of primary importance in any gas burning appliance installation is the care and workmanship which is exercised. The gas piping or tubing should be of proper size and strength, run neatly with strapping to rigid building members at reasonable intervals, and protected against possible mechanical damage. Fittings should likewise be of adequate strength and quality to match the pipe or tubing and should be carefully assembled to assure tight joints. Where used, pipe thread compounds and gasket materials should be of compositions which are not affected by the gas. National Board of Fire Underwriters Pamphlet No. 54 gives the standards for the installation and maintenance of appliances burning natural or manufactured gas. Some, but not all, of the principles outlined in this pamphlet are applicable to other kinds of gases. Its requirements for flues and vents apply substantially to all fuel gases.

After an appliance is installed the piping or tubing should be very carefully tested for leaks. In case of a large leak the gas supply should be shut off and the piping visually inspected. Small leaks can be located while the system is under operating pressure by applying soapy water or a bubble forming compound liberally to the lines and joints; expanding bubbles will show up the leaks. Under no circumstances should matches or open flames be used for leak testing on flammable gas lines.

Proper operation of the appliance should likewise be carefully checked and verified by the installer. This is particularly important in the case of appliances using burners automatically controlled by thermostats. Not only the thermostat but the automatic shut off device should be checked through at least one full cycle of operation. This is usually done by extinguishing the pilot flame and then determining the length of time required for the safety shut off device to function and close the main gas line to the burner.

Lastly, it is extremely important for installers to instruct customers in the proper operation of the gas burning appliances. The manufacturer's written instructions should be left with the customer, preferably posted in a conspicuous place near or on the appliance. The customer should be advised as to what periodic maintenance work the device will need and at what intervals of time. Before leaving the job the installer should inform the customer as to what concern or person is qualified to render service work on the device, with the telephone number preferably posted conspicuously on the appliance.