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Gas Pipe Size Calculator
Calculate the correct gas pipe size for natural gas installations. Enter the gas flow rate, equivalent pipe length, and system pressure to get the recommended pipe diameter.
How to Size Gas Pipes
Gas pipe sizing ensures the pressure drop between the meter and the appliance stays within allowable limits. For low-pressure natural gas (21 mbar), the maximum pressure drop is 1 mbar.
The pipe size depends on the gas flow rate, pipe length (including fittings as equivalent lengths), and allowable pressure drop. Always follow BS 6891 for installation standards.
Frequently Asked Questions
What is the maximum pressure drop for low-pressure gas?
For low-pressure natural gas (21 mbar at the meter), the maximum pressure drop to the appliance is 1 mbar, giving 20 mbar at the appliance inlet.
How do I calculate equivalent pipe length?
Add the straight pipe length plus equivalent lengths for fittings: each elbow = 0.5 m, each tee = 0.5 m, each valve = 1–2 m. The equivalent length accounts for the additional friction of fittings.
Gas Pipe Size Calculator
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