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How to Check Inlet Gas Pressure

Whether you're a technician dealing with a gas appliance at the residential or commercial level, the working output of any gas appliance depends on the gas pressure. Abnormal gas pressure, i.e. too high and low, can cause issues while starting the unit. At very high pressure, the gas appliance will not be able to start; while in the case of very low pressure, the appliance will make noise and does not pass the proper pressure of the gas. So, it's essential to check the inlet gas pressure before using the gas appliance. 

It is recommended to hang the manometer inside the inlet to measure the gas inlet's pressure. It will keep you remembering to check inlet gas pressure. 

Learn more about how to test gas inlet pressure with the guide below. 

How to Check Inlet Gas Pressure Using a Manometer

  • Step 1: Switching manual gas valve—First of all, don't forget to turn off the manual gas valve on the appliance.
  • Step 2: Opening the hot faucet—Allow the unit to turn on to take the reading by opening the hot faucet. Then make sure to turn it on until the gas pressure decreases down. 
  • Step 3: Pressure port—You will see the pressure port on the appliance's inlet; it is needed to remove the screw of the pressure port.
  • Step 4: Connect the ManometerNow, you are allowed to connect the manometer with the gas inlet pressure section. Before connecting the manometer, make sure the reading of the manometer is zero.
  • Step 5: Checking the Gas LeakageEnsure there is no gas leakage on the inlet by turning on the manual gas valve on the appliance. Make sure there is no gas leakage. 
  • Step 6: Passing the Gas Pressure—Allow the gas inlet pressure to pass through multiple facets that have high flow rates.
  • Step 7: Take the Readings—Once the appliance has appropriately started blazing, check the manometer and observe the readings of inlet gas pressure that the manometer is showing. 
    • NOTE—The inlet gas pressure for the natural gas should lie between 5 to 10 W.C. While it should lie between 8 to 13.5 W.C for the liquid propane gas.
  • Step 8: Final Results—The reading should be kept in its specified range. Otherwise, it will affect the working output of the appliance.

What Should the Gas Inlet Pressure Be?

The ideal gas inlet pressure for the natural gas is 7 inches W.C or 14.9 millibars, and it is satisfied in the range of 5 inches W.C to 10 inches W.C. For propane gas, it should lie between the range of 8 inches W.C to 13.5 inches W.C. When it comes to the correct natural gas pressure for a piece of equipment, we recommend always checking the manufacturer data plate for the exact requirements. This previous article on techtown takes a closer look at this topic.

Safety Precautions When Dealing with Gas Under Pressure

  • Wear eye protection process
  • Use a face shield to protect yourself
  • Avoid heating the gas cylinder to increase the pressure
  • Please make sure the valve is closed when you are not using it or moisturized
  • Place the cylinder away from the electric field
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