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Gas Line Pressure

Gas Line Pressure

Pressure measurement in fuel gas systems may be of value in estimating flow rates through pilot light orifices or other components, or in validating adequate pressure during operation.

Installation of a pressure transducer in a gas system (e.g., natural gas or propane) requires opening gas lines, which is a hazardous operation. It must always be performed by a technician trained and licensed to perform work on fuel gas systems.

Table—Typical pressures in gas lines

Location

Natural gas

(inH2O)

Propane

(inH2O

)

In gas line, downstream of regulator at the gas meter, or outside the home

3.5 to 1410 to 14
Manifold pressure in appliance3.5 to 5About 10 

Application Notes

Gas valves on appliances such as water heaters and furnaces have internal pressure regulators that control main burner manifold pressure. Burner gas flow rates should not vary greatly as long as gas line pressure remains within appliance specs.

Pilot light gas flow can be estimated from measured gas line pressure and the pilot light orifice size.