Propane & natural gas BTUs and gas pressures:

Here we provide descriptions and photographs of unsafe gas piping, indications of unsafe or improperly operating gas appliances, gas meters, and other gas installation defects are provided. This document provides free sample draft home inspection report language for reporting defects in oil and gas piping at residential properties.

LP "Bottled" Gas or Natural Gas Pressures & BTUH per Cubic Foot

General safety warning: improper installation and even improper inspection and testing methods involving natural or "LP" gas can involve dangerous conditions and risk fire or explosion.

If you smell gas you should leave the building immediately and should do so without doing anything that could create a spark such as operating a light switch or telephone. From a safe location, call your gas company's emergency line and/or your fire department. The text provided here is a working draft and may be incomplete or inaccurate.

Photo at page top and left: gas meters by American Meter Company. At page top is the AC250 for which we provide more data at the end of this article. Just above is the American Meter - Singer Co. AC-95 gas meter.

Discussed here: How to Calculate, Measure, & Set LP "Bottled" Gas or Natural Gas Pressures & BTUH per Cubic Foot. What are the typical pressures in an LP or natural gas fuel system & how do they differ. What's the difference between butane & propane or natural gas? Can we just substitute butane for propane or LPG? [No.]

How to calculate the BTU capacity of LP or natural gas fired equipment, heaters, or appliances

Computing BTUH: Technical Note: you can compute the BTU's per hour of gas consumption of your gas-fired equipment. Making sure than only a single gas appliance is running, watch the gas meter and measure the time required to use one cubic foot of gas.

The formula: (3600 x 1000)/seconds = BTUH.

The number you compute for BTU capacity for an appliance should approximately equal the appliance's nameplate "input" BTUH on the appliance.

How many BTU's are in a cubic meter or foot of natural gas?

• One cubic foot (0.028 cubic meters) of natural gas contains about 1,050 BTUs or 1,037 BTUs (US EIA)
• One cubic meter (35.3 cubic feet) of natural gas contains about 36,303 BTUs

How many BTUs are in a gallon of LP gas or propane?

• One cubic foot (0.028 cubic meters) of propane contains about 2,516 BTUs
• One cubic meter (35.3 cubic feet) of propane provides about 88,060 BTUs
• One pound of propane provides 8.45 cubic feet of propane
• One gallon of propane weighs 4.22 pounds
• One gallon of propane provides 35.65 standard cubic feet of propane gas
• One gallon of propane contains 91,500 BTUs

How many cubic feet of natural gas or propane will a heating furnace or boiler consume per hour?

• A 100,000 BTUh furnace will use about 95 cubic feet of natural gas (100,000 ÷ 1,050 = 95.21) in an hour of "burner on" time
• A 100,000 BTUh furnace will use about 40 cubic feet of propane (100,000 ÷ 2500 = 40) in an hour of "burner on" time

 

How to calculate the conversion of gallons of propane or natural gas to pounds or BTUs or to volume of gas

One gallon of propane contains about 91,500 BTUs and weighs about 4.20 pounds. One pound of propane contains about 21,500 BTUs. Calculation details are below.

One gallon of LP-gas (propane or C₃H₈) weighs about 4.20 lbs (at 60°F), contains about 8.66 cubic feet of gas vapor per pound (at 60 deg. F), burns at 3,595 degF in air, and requires 23.86 cubic feet of combustion air to burn properly.

Converting between cubic feet of gas and liquid gallons, keeping temperature constant helps decode typical gas meter readings given in cubic feet.

• 1 gallon of LP gas C₃H₈ = 4.20 lbs (at 60 degF) and contains 8.66 cu. ft. per pound
• 4.20 pounds x 8.66 cu. ft./pound = 36 cubic feet of gas (at 60°F) per gallon of LPG

or since 1 gal of LPG = 36 cu. ft. of propane gas, we can write:

• 1 cubic foot of LP gas C₃H₈ = 1/36 gallons of liquid LP or about 0.3 liquid gallons (at 60°F)

Butane Gas Properties

The numbers for butane gas (C₄H₁₀) are different. One gallon of LP-gas composed of butane:

• 1 gallon of butane weighs about 4.81 lbs (at 60 degF),
• 1 gallon of butane contains about 6.51 cubic feet of gas vapor per pound (at 60 deg. F),
• Butane burns at 3,615 degF in air, and
• To Burn 1 gallon of butane requires 31.02 cubic feet of combustion air to burn properly.

[Metric equivalents of these amounts are available from the website author or from the LP Gas Service Handbook cited below.]

Thanks to reader Fred G. Van Orsdol for correcting our weights and measures for LP gas. Thanks to reader Bay Ground Control for additional technical editing.

How to Convert cubic feet of natural gas / hour to BTUs / hour

Multiply cubic feet per hour by 1,050/cubic foot of natural gas to obtain BTUH.

• BTUh = (CuFt / Hour Use Rate) x (1,050 BTUs per cu.ft )

What are the common operating pressures of natural gas and LP or "liquid petroleum" gas in the building gas piping and at the appliance?

The Common operating pressure for natural gas is 3.5" of water.

Common operating pressure for liquid petroleum or LP gas is 10" of water.

Details about LP gas pressures and natural gas pressures as they occur at buildings and in gas fired appliancs are found

at GAS PRESSURES LP vs NATURAL GAS.

LPG LP Tank Sizes, Capacities in BTUs, Weights, Volumes

Here is a table of the sizes and capacities of smaller LP gas tanks typically used for local LP gas supply at homes and in smaller sizes also at food trucks or RVs.

How Long Should a Full LP Gas Tank Last?

LP Gas Cylinder Supply Time Formula

Supply Time in Hours (T) = (Tank Total BTUs / Appliance Input BTUh)

Example:

Reader Question: How long will my 29.3 gallon LP Tanks Last in my Food Truck?

I have a food truck and all the equipment will produce 988,000 Btu's. Im planning to use 29.3 gallon horizontal propane tank. My question is how many 29.3 gallon tanks should I use to supply to right amount of pressure for the equipment. Average running time will be 4-5 hours. - Skee 2021/12/09

This Q&A were posted originally

at GAS BTUH, CUBIC FEET & ENERGY

Illustration, adapted from New York City's Food Truck LP Gas Regulations cited below.

Reply:

Two nominal 30-gallon LP tanks, when full, contain about (649,980 x 2) or 1,299,960 BTUs of propane.

Your LP fuel supply time in hours is given as

T = (1,299,960 Btus / 988,000 input BTUh)

T = 1.3 hours

Typical Maximum LP or Propane or Natural Gas Storage Capacity for Mobile Food Vehicles

As an aside since we acknowledge that you didn't ask:

Watch out: Typically a mobile food vehicle is allowed to carry no more than a total of 40 lbs (40 pounds) of propane, either in a single LP tank or in a pair of them.

Using the New York City standard provided below, if by fire department permit, permit you are permitted to carry up to to two LP gas cylinders of 100 lbs each for a total of 200 lbs,

that would give you a total run time

T = (total storage / input BTUh)

T = (2,160,509 + 2,160,509) / 988,000

T = 4.3 hours - still less than you say is your 5-hour maximum run time.

So you may want to be sure you've got that input BTUh number right for your food truck.

Your fuel supply won't last for the 5- hour period of active use per day that you indicated.

Food Truck LP Gas Storage Safety Warnings

Watch out: Following a disastrous food truck LP gas explosion in Feltonville in Philadelphia in 2014 the NFPA produced

• NFPA 96: Ventilation Control and Fire Protection of Commercial Cooking Operations (2017) focused on food truck safety.
  You should certainly review that information as well as the 2018 edition of NFPA 1: Fire Code that contains related safety advice for use of LP and LP storage on food carts and food trucks.

We don't know where you are but you will also want to revew these example

• FOOD TRUCK/CART LP FUEL STORAGE REGULATIONS - New York City [PDF] retrieved 2021/12/09 original source: https://www1.nyc.gov/assets/fdny/downloads/pdf/business/Support/use-store-LPG-food-cart-commissaries.pdf

How much gas do various household appliances and systems use?

The following are approximate since there is a wide range in fuel usage rate among appliances and between conventional and "high efficiency" heating systems. But according to NFPA Pamphlet 54 and the LP Serviceman's handbook (cited below), common household gas appliances consume LP gas roughly at these rates:

• Gas-powered clothes dryers,
  
  residential types, use about 35,000 BTUs per hour (BTUH)
• Gas Ovens and Stove gas 
  
  consumption rates: A residential gas range can burn about 65,000 BTUs per hour (BTUH), while the oven may consume about 25,000 BTUH.
• Gas -fired residential water heater 
  
  gas consumption rate: A typical residential water heater used to produce domestic hot water consumes about 45,000 BTUH for a 30 to 40 gallon water heater.
• Gas-fired "on demand" tankless water heaters 
  
  burn gas at a much faster rate, ranging from about 140,000 BTUH (2 gpm water flow and assuming incoming water at about 40 degF and outgoing at about 120 degF or less) and can burn up to about 430,000 BTUH at 6 gpm water flow.
• Gas-powered refrigerators are much smaller consumers, using about 3,000 BTUH.

Gas service people and installers, in deciding on the total LP gas load at a property, may use "standard cubic feet per hour" or SCFH which is calculated by adding up the total anticipated gas appliance load (in BTUs per hour) and dividing by 2488.

The total gas requirements at a building are used to determine the necessary distribution piping sizes as well as the gas tank size most appropriate.

Other LP Gas Characteristics

• Chemical Formula for LP Gas: C3H8
• Ignition Temperature for LP Gas: 920 - 1,120 degrees Fahrenheit
• Maximum flame temperature for LP Gas: 3,595 degF
• Heat value per cubic foot of vapor of LP gas (atmospheric pressure): 2,516 BTUs
• Heat value per pound of liquid LP gas: 21,591 BTUs
• Heat value per gallon of liquid LP gas: 91,547 BTUs
• Specific gravity of liquid LP gas: 0.509
• Specific gravity of vapor-form LP gas (at atmospheric pressure, sea level): 1.52
• Therms: 1 therm = 100,000 BTUs of natural gas - a measure used on some natural gas meters
  
  - see also THERMS
• Weight per gallon of liquid LP fuel: 4.24 U.S. pounds

-- National Propane Gas Association - cited below

Propane & Methane Constituents, UN/NA Numbers & Formulas

UN/NA numbers are 4-digit numbers assigned by the United Nations and the U.S. Department of Transportation to identify hazardous substances.

These numbers are also found on the Material Safety Data Sheet or MSDS for these substances, and when being transported as dangerous goods, a sign indicating the UN/NA number of the substance being transported must be affixed to the vehicle.

Propane (C₃H₈) or LP Gas: UN/NA: 1075, CAS: 74-98-6

UN/NA 1075 is used for: Butane Butylene Isobutane Isobutylene Liquefied petroleum gas LPG Petroleum gases, liquefied Propane Propylene

Methane (CH₄) or "natural gas" (this is the largest component in natural gas): UN/NA: 1971, CAS: 74-82-8

UN/NA 1971 is used for: Methane, compressed methane, and compressed natural gas

Liquified Natural Gas or LNG: UN/NA: 1972

UN/NA 1972 is used for Liquefied natural gas (cryogenic liquid), LNG (cryogenic liquid), Methane, refrigerated liquid (cryogenic liquid) and Natural gas, refrigerated liquid (cryogenic liquid)

Besides methane, natural gas contains smaller amounts of carbon dioxide, ethane, and propane as well as some water vapor.

Source: Cameo Chemicals, database of hazardous materials at https://cameochemicals.noaa.gov/search/simple U.S. Government

Fuel Alternatives for Heating Appliances: Butane, Natural Gas, Propane: proper set-up required

At TANKLESS WATER HEATER INSTALLATION we noted that several readers had asked about using butane in tankless water heaters and we commented that several manufaturers, at least including Bosch, make conversion kits for their water heaters that include butane as well as LP gas and Natural Gas.

The proper match of the appliance set-up to the fuel is important.

Watch out: do not simply hook up a water heater or any other gas fired device without checking the intended fuel against the heater's current set-up. While most heaters can be converted among fuels, using a fuel different than the current jets and air and fuel metering controls on the appliance would be dangerous, not to mention that the device won't work properly.

Butane is used as a fuel gas alone or in some areas may be mixed with propane. Adapting text from Wikipedia & Princeton University:

Butane gas is sold bottled as a fuel for cooking and camping. When blended with propane and other hydrocarbons, it is referred to commercially as LPG ["liquid petroleum gas" or LP gas].

Butane is also used as a petrol component, as a feedstock for the production of base petrochemicals in steam cracking, as fuel for cigarette lighters and as a propellant in aerosol sprays such as deodorants.

Very pure forms of butane, especially isobutane, can be used as refrigerants and have largely replaced the ozone layer-depleting halomethanes, for instance in household refrigerators and freezers. The system operating pressure for butane is lower than for the halomethanes, such as R-12, so R-12 systems such as in automotive air conditioning systems, when converted to butane will not function optimally. - Wikipedia (2104) & Princeton (2014)

For example, even though many sources refer to both Butane and Propane as LPG or liquified petroleum gas, Butane is not an exact substitution for Propane in all applications as the latter form of propane is commonly sold for use in heating appliances. Quoting from Avantigas in the UK

There are two types of LPG - Propane and Butane. They have similar properties but different applications. They are not interchangeable due to the different operating pressures and burner settings required. Valves and fittings are also different to avoid confusion or accidental use of the wrong type of LPG.

Propane has a lower boiling point than butane so it will continue to convert from a liquid to a gas even in very cold conditions, down to -45ºC. When stored as a liquid in a tank, it exerts a greater pressure than Butane at the same temperature.

... Propane, as an LPG, is most suitable for exterior storage and use. Its ability to operate in low temperatures makes it the most suitable LPG for many applications.

Propane is widely used as a fuel source for domestic and commercial heating, hot water and cooking....

Butane has the lower vapour pressure at equivalent temperatures and is suitable for interior use or outside during the summer. Butane is a very common fuel amongst leisure users and owners of portable heaters. .... - Avantigas (2014) www.avantigas.com U.K.

Propane & Natural Gas Properties References

• AvantiGas, "Propane and Butane, Know your LPG", Avanti Gas Ltd Avanti House, PO Box 1100, Chesterfield, Derbyshire. S44 5YQ UK United Kingdom Tel: 0808 208 0000 Email: enquiries@avantigas.com Retrieved 3/3/2014, original source: http://www.avantigas.com/propane-butane/
• APVGN, Associação Portuguesa do Veículo a Gás Natural
  Portuguese Natural Gas Vehicle Association - apvgn.pt/documentacao/iangv_rep_part1.pdf [DEAD LINK - 2023] listed the components in natural gas exhaust from vehicles\
• [1] Bosch Tankless Water Heaters - http://www.boschhotwater.com/
  • [1a] Bosch, "Instrucciones de instalacion y manejo, Calentador de agua instantaneo, Confort / Confort S 6BP / 6BP n 10BP / 10BP N 13BP / 13BP N" Robert Bosch, S. de R.L. de C.V., Calle Robert Bosch 405, Zona Industrial, Toluca, Edo de Mexico CP 50070, website: www.bosch.com.mx, Tel: 800-11-26724 (2010)
  • Geocities: At geocities.com/rainforest/6847/report1.html is an interesting and detailed though not “neutral” report on the components and contaminants in the combustion of natural gas. You’ll see a long long list of emissions products, but look again – most of the contaminant levels listed are in the picograms.
• Natural Gas.Org www.naturalgas.org/environment/naturalgas.asp#emission you’ll find a table of combustion products
• Princeton University, "Butane", Princeton University, retrieved 3/3/2014, original source: https://www.princeton.edu/~achaney/tmve/wiki100k/docs/Butane.html
• Kroschwitz, Jacqueline I., and Mary Howe-Grant (eds.). "Gas, Natural." In Encyclopedia of Chemical Technology. 4th ed., vol. 12. New York: John Wiley and Sons, Inc., 1993.
• National Propane Gas Association, industry trade association, at http://www.npga.org, National Propane Gas Association, 1899 L Steet, NW, Suite 350, Washington, DC 20036, Phone: 202-466-7200, Fax: 202-466-7205
  
  "The National Propane Gas Association (NPGA) is the national trade association representing the U.S. propane industry.
  
  Our membership includes small businesses and large corporations engaged in the retail marketing of propane gas and appliances; producers and wholesalers of propane equipment; manufacturers and distributors of propane gas appliances and equipment; fabricators of propane gas cylinders and tanks; and propane transporter"
• Need.org The Need Project, Manassas, VA: need.org/needpdf/infobook_activities/SecInfo/NGasS.pdf
• Tussing, Arlon R., & Bob Tippee. The Natural Gas Industry: Evolution, Structure, and Economics. 2nd ed. Tulsa, OK: PennWell Publishing, 1995.
• US EIA, WHAT ARE CCF, MCF, BTU, AND THERMS? HOW DO I CONVERT NATURAL GAS PRICES IN DOLLARS PER CCF OR MCF TO DOLLARS PER BTU OR THERM?[PDF]
• [11] US DOE, "Tankless or Demand Type Water Heaters,"U.S. Department of Energy, retrieved 10/14/2012, original source: http://energy.gov/energysaver/articles/tankless-or-demand-type-water-heaters [Copy on file as Tankless_Water Heaters_DOE.pdf]
• [10] U.S. Department of Energy on TANKLESS WATER HEATERS - http://apps1.eere.energy.gov/consumer/your_home/water_heating/index.cfm/mytopic=12820
• U.S. Energy Information Administration - eia.doe.gov/
• U.S. Environmental Protection Agency - epa.gov/solar/energy-and-you/affect/natural-gas.html

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-11-30 - by (mod) -

Yes, Charlie.

Depending on the run length and diameter and total input BTUH required by your gas fired heaters the line may be too small; if you can't get enough flow rate then the gas appliances will not work properly.

On 2020-11-30 by Charlie Pratt

I have a 5/16 copper line from a pad to the house. It's run through 1/2" PVC and burred 3' deep. It was originally used to run a gas fire place. I'm adding a gas stove and furnace.

What I'd like to do is run the pigtail from the tank directly to 5/16 copper, thus running the copper at tank pressure to a two stage regulator mounted in a fire resistant box on the side of the house. Then run the rest of the system in the home using standard 1/2' copper. Is there any reason why this won't work just fine?

On 2015-06-24 by Anonymous

For natural gas, what psi is needed at regulator for 3.97 mmbtu per hour, for grain bin dryer? Do I need 5psi or 10 psi?

On 2015-04-25 by Jeff

Looking for chart for 120 gallon LP vaporization rate
Temperature and percent full

On 2015-02-26 by Stephen

Pls can anyone help with the dimension of a 5 ton butane tank.....thansk

On 2015-02-16 by Mark

When sizing gas piping why do we figure natural gas in cubic ft/hr but propane in thousands of BTU? When I figure for natural I divide the BTU rating of the appliance by the heating value of the gas (1050) to obtain CF/H. I usually do the same for propane ( BTU/2520)Is this correct or am I supposed to just use the figures on the propane chart without dividing?(The charts for natural are listed in cubic feet per hour while the charts for propane list demand in thousands of BTU per hour)

On 2015-01-08 - by (mod) -

Anon there is no single right answer to your question since the burn time of a pound of propane depends on the consumption rate of the appliance doing the burning. A pound of propane might keep a pilot light going for months or longer but might fire a high BTUh kiln for just a short time. So ... it depends, as Mark Cramer says.

On 2015-01-07 by Anonymous

how many hours will 1 pound of propane burn?

On 2014-12-21 by Kirk

Can anyone help me figure this please?
If I know the propane pressure, temperature, pipe length, and pipe diameter at my facility; How do I calculate volume in gallons?
Thank you kindly

On 2014-12-21 by Kirk

Can anyone help me figure this please?
If I know the propane pressure, temperature, pipe length, and pipe diameter at my facility; How do I calculate volume in gallons?
Thank you kindly

On 2014-05-05 by Anonymous

I want to use gas fired absorption chiller of 5 tons for my house, want to know what size of gas cylinder and how much gas per day required.

...

Continue reading  at GAS PRESSURES LP vs NATURAL GAS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see GAS BTUH, CUBIC FEET, ENERGY FAQs - answers to questions posted originally at this article

Or see these

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• GAS CONCENTRATIONS in AIR
• GAS METERS
• GAS PIPING SIZE & MATERIAL
• GAS PRESSURES LP vs NATURAL GAS
• GAS REGULATORS & APPLIANCE / HEATER CONTROLS
• GAS REGULATORS for LP TANKS
• GAS SAFETY HAZARDS
• GAS TANKS LP / PROPANE
• LPG PROPANE TANK PRESSURES
• NATURAL GAS EXPOSURE HAZARDS
• PROPANE GAS EXPOSURE HAZARDS

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