Sample interview questions: Can you explain the process of sizing gas lines for high-pressure or high-flow applications?
Sample answer:
Determining Gas Line Size for High-Pressure/Flow Applications
Step 1: Calculate Gas Flow Rate
- Determine the maximum gas usage (in cubic feet per minute or CFPM) of all gas appliances connected to the line.
- Use manufacturer’s data sheets or industry guidelines to estimate CFPM for each appliance.
- Calculate the total gas flow rate by adding the CFPM for all appliances.
Step 2: Determine Pressure Requirements
- Identify the pressure requirement of the gas appliance with the highest demand.
- Use manufacturer’s specifications or the International Gas Code (IGC) to determine the minimum operating pressure.
Step 3: Select Gas Line Material
- For high-pressure applications (>5 psi), use Type L copper or CSST (corrugated stainless steel tubing).
- For high-flow applications, choose gas lines with a larger internal diameter (ID).
Step 4: Apply Sizing Formula
- Use the following formula to determine the minimum inside diameter (ID) of the gas line:
ID = (CFPM * 30) / (P * 0.6)