Propane gas regulators control the flow of gas released from the supply tank. The regulator contains a valve with a spring that applies pressure to a rubber diaphragm, separating the regulator into high and low pressure sides. The high pressure side of the regulator attaches to the propane supply tank, with the low pressure side connecting to the system's supply hose. When a propane regulator fails, the cause is usually related to damage to the rubber diaphragm. You can tell if a propane regulator is bad by performing a pressure test with a manometer.
Prepare the system for as pressure flow test. Close the shutoff valve at the propane tank. Remove the outlet test port plug on the low pressure side of the regulator with a wrench. Screw the threaded test fitting of the manometer into the test port until it is hand-tight, and then tighten gently with a wrench. Push the hose of the manometer over the barbs of the test port with your fingers.
Open the gas supply valve and relight all the pilot lights for all appliances connected to the system. Check the reading on the manometer; it should be holding steady at 11 water column inches of pressure. If not, unscrew the cap from the regulator's spring valve tower, and turn the adjustment screw in or out, until the pressure reaches 11 water column inches.
Turn on all appliances connected to the gas system, to their highest settings. Wait five minutes to confirm the pressure reading on the manometer remains stable. Pressure fluctuation at this point indicates the regulator is faulty, and you do not need to continue with the test.
Perform a lock-up test on the regulator. Turn off the controls of all appliances and then close the gas valves of each individual appliance. The pressure reading on the manometer should immediately increase, but by no more than 30 percent, or to a maximum pressure of 14.3 water column inches of pressure. This is "lock-up" pressure; the maximum pressure a properly functioning regulator will allow the system to reach. Continue to watch the reading on the manometer for one minute. If the pressure continues to rise, the regulator is faulty.