Sample interview questions: Can you explain the process of sizing gas lines for longdistance or highvolume applications?
Sample answer:
Process of Sizing Gas Lines for LongDistance or HighVolume Applications:

Determine Gas Demand: Calculate the maximum hourly gas consumption (CFH) for all appliances powered by the gas line.

Choose the Pipe Material: Select a gas pipe material suitable for the application, such as polyethylene (PE), steel, or copper.

Calculate the Pressure Drop: Determine the allowable pressure drop based on the appliance manufacturer’s specifications and code requirements.

Estimate Pipeline Length: Measure the total length of the gas line from the source to the end point.

Select the Pipe Diameter: Use the following formula to calculate the required pipe diameter (in inches):
Pipe Diameter = √(Q * (Lw + Ln) * F * 1.54 / (P1²  P2²))
where:
 Q = gas demand (CFH)
 Lw = equivalent length for fittings and valves (feet)
 Ln = length of the gas line (feet)
 F = friction factor (depends on pipe material and flow rate)
 P1 = inlet pressure (psi)
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