Question? Just ask us!
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
InspectAPedia ® Home
PLUMBING SYSTEM INSPECT DIAGNOSE REPAIR
BACKDRAFTING HEATING EQUIPMENT
DRAIN & SEWER PIPING
FLOODED HEATING EQUIPMENT REPAIR
FLOODED WATER HEATER REPAIR
GAS DETECTION INSTRUMENTS
GAS EXPOSURE EFFECTS, TOXIC
GAS EXPOSURE LIMITS & STANDARDS
GAS FIRED WATER HEATERS
GAS LP & NATURAL GAS SAFETY HAZARDS
GAS LP & Natural Gas Pressures
GAS PIPING, VALVES, CONTROLS
GAS BTUH, CUBIC FEET & PRESSURES
GAS CONVRSION LP-NATURAL GAS
GAS FLAME & NOISE DEFECTS
GAS IGNITER DEFECTS & REPAIRS
GAS LEAK DETECTION, LP / NG
GAS LIGHTING, PIPES, FIXTURES
GAS PIPING DEFECTS
GAS REGULATORS for APPLIANCES
GAS REGULATORS for LP TANKS
Gas Regulators, Two Stage
GAS SHUTOFF VALVES
LP Gas Tanks
GAS LP & NATURAL GAS SAFETY HAZARDS
LP & Natural Gas Pressures
METHANE GAS SOURCES
Natural Gas Combustion Products
SPILL SWITCHES - Flue Gas Detection
Types of Fuel Gas Source
MANUALS & PARTS GUIDES - HVAC
METHANE GAS SOURCES
ODORS GASES SMELLS, DIAGNOSIS & CURE
ODORS, SEPTIC or SEWER
ODORS, SULPHUR SMELL SOURCES
OIL TANK PIPING & PIPING DEFECTS
PIPING IN buildings, Clogs Leaks Types
SEWER GAS ODORS
SHUTOFF VALVE LOCATION, USE
SULPHUR & SEWER GAS SMELL SOURCES
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.
Green links show where you are. © Copyright 2014 InspectApedia.com, All Rights Reserved.
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.
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? How many BTUs are in a gallon of LP gas or propane?
How many cubic feet of natural gas or propane will a heating furnace or boiler consume per hour?
How to calculate the conversion of gallons of propane or natural gas to pounds or BTUs
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 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 gallon 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.
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 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
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:
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
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs)
No FAQs have been posted for this page. Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.
Questions & answers or comments about LP (propane) or natural gas pressures and BTUs.
Try the search box just below or if you prefer, post a question or a comment in the Comments box below and we will respond promptly.
Search the InspectApedia website
HTML Comment Box is loading comments...
Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.