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• How to Calculate, Measure, & Set LP "Bottled" Gas or Natural Gas Pressures & BTUH per Cubic Foot
• How to report defects found in oil or gas piping inspections
• Home inspection report language examples

This document provides free sample draft home inspection report language for reporting defects in oil and gas piping at residential properties. 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. 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. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. Also see How to Report Defects in Oil Piping. NOTICE: while example report language is provided here, reproduction of this or any of our web pages or their contents at other websites or in printed documents for sale is prohibited. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Un-Biased Reporting are Assured for this website - see pledge link at below-left.

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

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 foot of natural gas?

One cubic foot of LP-gas (propane or C₃H₈) weighs about 4.20 lbs (at 60 degF), 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. The numbers for butane gas (C₄H₁₀) are different. One cubic foot of LP-gas composed of butane weighs about 4.81 lbs (at 60 degF), contains about 6.51 cubic feet of gas vapor per pound (at 60 deg.F), burns at 3,615 degF in air, and 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.]

How to Convert cubic feet of natural gas to BTUs/hour: multiply cubic feet per hour by 1,020/cubic foot of natural gas to obtain BTUH.

What is pressure of natural gas and LP or "liquid petroleum" gas inside the gas tank?

There is some confusion, even among LP gas service technicians about just what is the pressure inside the gas containers they deliver to or fill at properties. Perhaps this is because the gas laws (see Boyle's Law discussed at this website, for example), explain that the vapor pressure of LP-gases varies as a function of temperature. "Vapor pressure" is the force exerted by a gas, LP gas in this case, attempting to escape from a container (say by pressing on the container's interior surfaces, or exiting at a gas valve if the gas valve is opened and not regulated). Some typical vapor pressures of LP gas (propane) are given just below. These pressures vary in real life depending on the purity of the gas and the percentage mixture of propane and butane. Butane is generally going to show a much lower vapor pressure in the container than propane. But you can see from the table that as outdoor temperature varies between zero and 80 deg.F., the pressure of LP gas in the outdoor tank varies widely, from about 28 psi to as much as 140 psi. Since the temperature affects the vaporization rate of LP gas stored at a property, you can understand that your full LP tank will appear to "last longer" in warmer weather not just because your heating boiler is not drawing on the tank, but because of the higher outdoor temperature.

Source: "LP Gas Serviceman's Handbook", cited at references below.

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.

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

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Technical Reviewers

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

• Daniel Friedman - InspectAPedia.com ^TM Website Author/Editor
• National Fuel Gas Code, ANSI Z223.1-yyyy - American Gas Association / National Fire Protection Association
• LP-Gas Serviceman's Handbook,Fisher-Rosemount, Fisher Controls
• National Fire Protection Association (NFPA) Pamphlets No. 54 and 58.
• Specifications for Gas Installations, Central Hudson Gas and Electric Corporation
• "Gaslight", Gary Quilliam, The Old House Journal, March/April 1989 article describes fixtures, modern fixtures, and sources of supply.
• Residential Gas Hot Water Heater Pocket Partner - Testing and Trouble Shooting, 19. State Corp., Ashland City, TN 37015
• Also See: - HW Boilers: Leaks, Corrosion, Expansion Tanks, Air Purge
• Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

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