LP gas tank regulatorInstall, Inspect & Test LP Gas Tank or Gas Cylinder Regulators
Gas regulator pressure & flow test procedure

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This article explains LP Gas Pressure Regulators used on LP Gas or Propane tanks.

How to Inspect & Test LP Gas Valves Regulators, or Gas Controls and we provide descriptions and photographs of unsafe LP gas piping, LP gas regulators, or LP gas valves & controls on appliances or heating equipment.

We describe indications of unsafe or improperly operating gas appliances, gas meters, and other gas installation defects.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

LP or Natural Gas Tank / Cylinder Regulator or Control Inspection, Testing, & Defect Guide

Article Contents

Watch Out: Immediate LP or natural gas safety hazards:

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.

If there is evidence of an LP or natural gas leak at a building, gas odors, for example, you should:

Types of Gas Regulators Used at Gas Tanks, Cylinders, Appliances

LP gas cylinder regulator (C) Daniel Friedman

[Click to enlarge any image]

Above: a first (and only) stage LP gas regulator installed on a gas tank (gas cylinder) in New York. In a better installation the vent on this regulator would have been aimed downwards.

Because of varying requirements, LP gas regulator types found at a typical residential or light commercial property may vary using:

Other regulators less likely to be found at a residential property include:

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

Location & Position of the LP Gas Cylinder or Tank Regulator

LP gas regulator vent

An LP gas cylinder regulator should be mounted so that any moisture or condensate inside the regulator can drain out. Any drain openings should be facing downwards.

Otherwise water or in freezing climates ice can accumulate and damage the regulator, forming an unsafe condition.

The photograph of an LP gas cylinder regulator above shows the regulator's vent opening.

Photograph of the fill valve and regulator and tank gauge for a buried LP Gas tank

In photo at above the red LP gas regulator can be seen installed in a tipped position in upper center of the photo.

The installer felt that the regulator would drain in this position, and that when the plastic cover was installed on the control well (this is a buried LP gas tank) the regulator would be protected from the weather.

Location of the Gas Cylinder On-Off Valve on an LP Gas Tank / Cylinder

LP tank gas on off valve

The photograph at above left below shows at right the silver-colored LP gas tank on-off valve. An arrow on the valve will indicate the direction to turn the valve to close it or open it.

Normally you close the LP tank gas valve by turning it "clockwise" or as my daughter Mara says, "rightie-tightie, leftie-loosie" to help remember this important information.

The yellow cover on top of the valve is the connector for filling the LP gas tank.

The small-diameter copper tube leaving at the left side of the valve is the "high pressure" LP gas line carrying LP gas in vapor form from the top of the gas cylinder over to the LP gas regulator whose body you can just see in the upper left hand corner of this photo.)

Watch out: in addition to a gas supply shut off valve at the LP or propane gas cylinder or tank (or at the building gas main where piped-in natural gas is supplied), additional gas supply shutoff valves are required in the gas piping system at each gas-fired heating device or appliance.

How & Why to Protect an LP Gas Tank / Cylinder Regulator from Rain, Snow, Ice

An LP gas tank or cylinder regulator should be protected from the weather.

Water, particularly in freezing climates, can enter and block the safety vent on the gas regulator or ice can form preventing the regulator from properly controlling gas pressure. An iced or water-damaged gas regulator is unsafe.

LP gas tank regulator protected

Our photos above and below show how an existing LP gas tank regulator was protected from rain and weather by a simple rubber cover affixed to the building.

The protective cover was secured to the building wall and draped over the regulator. Despite formation of ice and icicles at the roof eaves and even atop the propane tank, the LP gas cylinder regulator was dry and functioning safely.

Ice cascading over an LP propane gas tank and regulator, New York (C) Daniel Friedman

This option (adding a protective cover for the gas cylinder regulator) was elected when a new LP gas tank (shown in this photo) was installed and connected to an existing regulator difficult to relocate. Below: Bottini fuel delivering LP gas to this home in winter.

Bottini fuel delivering LP gas in winter in Poughkeepsie (C) Daniel Friedman

Watch out: It is important that any cover protecting an LP gas regulator does not block fresh air flow around the regulator. Otherwise leaking LP gas can accumulate and form an explosion or fire hazard.

What goes wrong with gas regulators on LP Gas Tanks?

LP gas cylinder regulator in Two Harbors Minnesota (C) Daniel FriedmanWatch out: Immediate LP or natural gas safety hazards: if there is evidence of an LP or natural gas leak at a building, gas odors, for example, you should:

Gas pressure too high:

Adjustment of a gas regulator might also be necessary if the gas piping from source (meter or tank) to the appliance is long or is too small in diameter.

If the gas regulator delivers gas at too high a pressure the gas flame may be also too big (and too hot), which can accelerate rusting and can warp the heat exchanger at its lower joints causing a "crack" to appear. A cracked heat exchanger on a gas appliance is unsafe. Our correspondent, Charles commented that:

After loosing three heat exchangers in two different homes that had routine maintenance inspections, I decided to look into it and check the gas regulator pressure myself. The same problem can occur with gas water heaters.

Gas pressure too low: if the gas regulator is not properly adjusted or if there are other problems in the gas piping or supply system the gas pressure may be too low, providing an inadequate and possibly unsafe flame.

Depending on the cause of the problem, it may be possible to correct this at the regulator, but don't try boosting pressure at a gas regulator unless the pressure has always been too low. Otherwise when the underlying cause for low gas pressure is corrected elsewhere, the flame will be too big and pressure too high at the burner - an unsafe condition.

Disassembly of gas meters, regulators, valves & controls for inspection, testing, calibration

Watch out: SAFETY WARNING: If you lack the training and equipment, do not attempt to disassemble or mess with a gas regulator as you could create a very dangerous or even fatal problem.

What are the Typical LP Gas, Propane Gas, or Natural Gas Pressures Found in Residential Systems

Details about the different pressures found or set for LP gas, propane, and natural gas including before and after different gas pressure regulators are

LP Gas or Propane Pressures:

Natural Gas pressures:

Gas Regulator Pressure & Flow Test Procedures

Gas pressure gauge reading in inches of water column at InspectApedia.comQuestion: How do I check the gas coming out of my regulator for LP ? I

2018/01/18 Anonymous said:

How do I check the gas coming out of my regulator for LP ? It is for a commercial deep fryer on a Mobil truck.

Illustration: a typical gas pressure gauge reading in inches of water or Inch H2O as sold on eBay. Other gas pressure gauges and manometers are available in both digital and analog format.

[Click to enlarge any image]

Reply: How to test or check the gas pressure provided by an LP gas regulator:

Watch out: do not try testing nor adjusting your gas regulator output pressure unless you are equipped and trained to do so. A mistake can lead to a fire, explosion, injury, or death.

A plumber who is familiar with gas piping might use a pressure gauge and would, of course, check system piping safety including for leaks.

The plumber attaches a pressure gauge or a manometer to the regulator output side where she can see what pressure the regulator is delivering. Most 2-psi output gas regulators include a test port intended specifically for this purpose.

Other installations include a test-tapping upstream from the shutoff valve for your gas-burning appliance, in this case your deep fryer.

Or the plumber will install such a fitting to permit gas pressure testing.

LP Gas Regulator Pressure & Flow Test 5-step Procedure

Bosh Gas Regulator for a gas cooktop (C) Daniel Friedman

  1. Install a water column manometer or a suitable low-pressure gauge or measuring device in the second-stage regulator outlet test tap or in a test tap in the appliance gas shutoff valve at the gas appliance that is most-distant from the gas regulator being tested.
  2. Re-light all of the gas appliance pilots and turn the appliances on, confirming that the gas burners are all operating at their highest setting.
  3. With all of the gas-using appliance pilots lit and appliance gas burners operating (in your case maybe that's just one appliance), the flowing gas pressure (or "in-use" pressure rather than static pressure) is read at the pressure gauge or manometer.
  4. On a manometer, with at least half of the gas appliances working you have to see a total of 11 inches of water (pressure) on the readout scale. You may need to adjust the suppy regulator to achieve that pressure. If so, see GAS REGULATOR ADJUSTMENT PROCEDURE.
  5. Check the required LP or propane gas delivery pressure specified on the data tag that you will find attached to your deep fryer.

If the supply regulator cannot maintain the required flowing gas pressure the problem may be any of the following:

LP Gas Regulator Lock-Up Test Procedure

Gas valve with test port from Industrial Valve Co. at

An important additional gas pressure regulator safety check is for the "lock-up" gas pressure in your system.

To read Lock-up (or static) gas pressure,

  1. Turn off all of the gas-fueled appliances
  2. Turn off all of the individual gas appliances individual shutoff valves. Illustration: a gas valve with a test port, from Industrial Valve Co.
  3. Leave the LP gas tank gas valve open or "on" to keep providing gas pressure to the gas delivery system.
  4. You should see the gas pressure increase slightly (above the 11 inches of water column read before) and then the pressure rise should stop. This is the lock-up gas pressure.

    The lock-up gas pressure can be no more than 30% higher than the flow pressure.

    Example: with a flow pressure of 11" WC, the lock-up pressure can be no higher than (11 + .3 x 11) = 14.3" W.C.

    Converting inches of water column to psi for pressure gauge users and where 1" WC = 0.03609 psi we have:

    11" WC = 0.397 psi

    14.3" WC = 0.516 psi

Watch out: Document the regulator measurements made in both of these tests, including the date, location, test operator, test pressure results, and results of leak tests performed.

Watch out: if after a brief initial pressure rise the gas pressure continues to increase with all appliances off, the LP regulator is defective and must be replaced.

On a typical gas regulator an adjustment screw is turned clockwise, increasing pressure on the regulator's diaphragm, to thus increase the pressure of the gas being delivered.

Gas Regulator Test Procedure References

Gas pressure manometer reading in inches of water column  from Dwyer Instruments (C) InspectApedia.comIllustration: a gas pressure manometer reading in inches of water column or In. W.C.

This device is provided by Dwyer Instruments, cited below. Gauge type instruments (shown earlier on this page) reading in inches of W.C. or psi can also be used provided that the gauge is within the proper low-pressure range.


Continue reading at GAS REGULATORS, TWO STAGE or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see GAS REGULATORS for APPLIANCES - installing, inspecting, or testing LP or Natural Gas regulators which are found on appliances such as LP or Natural Gas fired boilers, furnaces, water heaters or appliances

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