System Pressure Test | Flow Test | Pressure Adjustment | Test for Failing Regulator | Leak Test

Ever ask - How do I know if my propane tank is getting filled correctly? Or how do I adjust my RV propane regulator pressure? How about, what is the official propane leak test for an RV?
This page covers these solutions, you are in the right place.

Propane Tank & Regulator

HOW TO USE THIS PAGE: This page is divided into two parts:
  • Text and Photos below with instructions to solve your system pressure issue, determine if proper flow is present, adjust the system pressure, and leak test information.

  • A YouTube video that shows the basics on how the LP tank can be filled properly, how to test system regulator pressure, how to build a manometer for pressure testing, and how to test the fridge propane pressure for poor cooling situations on LP gas mode.

LP Gas Pressure Regulator

This figure shows a typical RV with a dual tank automatic switching regulator. Please note that on this RV, there is a port for checking the regulator pressure output. A ‘u-tube’ water manometer is connected to the test port, and the manometer is showing 11 inches of water column (WC). Note that there is a zero on the inch measurement gauge that measures the green water in the manometer. With the LP valve off, one zeros the gage by aligning the zero with the water level before turning on the propane tank valve.

When the LP gas valve turns on, the side of the ‘u-tube’ that is connected to the pressure port, the water goes down by 5.5 inches, and the side open to the atmosphere goes up by 5.5”. The green arrows point this out, this is a total of 11” WC gas pressure.


Now that it is established that the pressure is correct, have someone turn on a burner on the stove, or the LP heater. Keep an eye on the pressure, it will jump and stabilize. As a rule of thumb, the pressure should not drop more than about ½” WC once the pressure stabilize.

Please see below: NFPA 1192 Standard on Recreational Vehicles 2021, section Pressure Drop Test


To adjust pressure, most regulators have a cap that covers the pressure adjusting screw; this is located just above the diaphragm red arrow. Remove the cap and turn the screw ½ turn at a time, counting the turns for reference. The reason the adjustment is there - to correct for drift in the regulator over time, this is normal. If one has to turn the adjustment screw say 10 full turns to get your pressure set, the regulator may be failing?


In addition to the comments above, the regulator can leak from the diaphragm. If you smell propane, turn off your gas and perform a bubble test immediately to find the leak. The propane regulator diaphragm always has a hole that vents the diaphragm; again this is where the red arrow is in the photo above. Find that hole, and one can put their finger over the hole and put a mixture of 50/50 water dish soap. If you see growing bubbles, the regulator needs to be replaced.


The test that is require at the factor by the NFPA 1192 Standard on Recreational Vehicles 2021, section Pressure Drop Test, is summarized as follows:

Pressure Test:

Pressure of not less than 8 inches water column or more than 14 inches of water column shall be used to test the system.

Leak Down Test:

After confirming above that the system pressure regulator is operational, turn off the propane at the tank. Carefully vent some pressure at the stove top so that the manometer reads 8 inches of water column. The system shall hold pressure for at least a 3-minute period with out any drop in pressure. If pressure drop is observed, the system failed the pressure leakage drop test.