Figure 2. Leak check using 30 lb gauge Checking for Leaks Using a Manometer (“U” gauge) or Equivalent Device. As stated in item (2) previously, another method is to use a manometer on piping systems serving appliances that receive gas at a pressure of ½psig or less may be leak checked by inserting a water manometer or equivalent device downstream of the final system regulator. It should be noted here that this is also suggested in NFPA 54 Annex C, C.3 (1). Titled “Leak check not using a gas meter” this procedure is for any gas system that includes natural gas. The leak check procedures using a manometer or equivalent device include the following steps: Step 1: Close the service valve at the propane storage container. Step 2: Connect a manometer or equivalent device at a convenient location downstream from the appliance shutoff valve. NOTE: A convenient location is the test tap opening on an appliance shut-off valve, installed upstream of an appliance equipped with a 100% pilot shut-off control. If such a test tap equipped shut-off valve is not available, an option is to install a special “test” adaptor between the appliance shutoff and the inlet to the appliance. Figure 3. Leak checking using a manometer or equilivalent device Step 3: Pilots not incorporating a 100% pilot shut-off valve and all manual gas valves not incorporating safety shut-off systems are to be placed in the “off” position prior to leak checking. Step 4: Slowly open the service valve at the propane storage container. Leave it open for two or three seconds, then close it. Step 5: Release enough gas from the piping system through a range burner valve, or other suitable means, to drop the system 30 pound Block Pressure Gauge with Presto-tap pressure to 9" ± %" water column. (This ensures that all regulators in the system are unlocked and that a leak anywhere in the system is communicated to the gauging device.) Step 6: Allow the piping system to remain pressurized for three minutes without showing an increase or decrease in the reading on the gauge. Step 7: Record the test pressure once the piping system is proven to be leak-free. Step 8: Close the shut-off valve, remove the manometer tube and test tap adapter and install the plug in the shut-off valve test tap, or reconnect the appliance line to the shut-off valve as applies. Open the valve to re-pressurize the test point and test for leaks at the test tap plug or joint using a suitable leak detection solution or device. If the shut-off valve test cap was used and is now leak-free, re-install the cover cap. Step 9: Purge the distribution piping of air in accordance with NFPA requirements. Re-light any equipment with pilots. In the next issue we will continue the discussion on testing covering leak test, flow test, lock-up test and testing using the gas meter. ICM 8 ICM/March/April 2016
ICM March-April 2016
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