Sizing a Commercial Seismic Gas Shutoff Valve

How the 2 inch to 8 inch sizes are determined by pipe size and gas demand, plus multi-meter buildings

Last updated: June 20, 2026

Overview

Commercial, multifamily, and industrial buildings usually need larger seismic gas shutoff valves than homes, commonly in the 2 inch to 8 inch range. The size is set by the gas pipe and the building's gas demand, not by floor area, and getting it right is the most common point of confusion on commercial projects. This guide walks through how the sizes are determined and what to have ready for a quote.

New to the topic? Start with the earthquake gas shutoff valve guide for valve types and the rules, or the requirements page for the code detail.

How Valves Are Sized

A seismic gas shutoff valve is selected to match two things:

Gas pipe diameter at the point of installation, which is downstream of the meter.
Gas demand, usually expressed in cubic feet per hour (CFH) or BTU per hour. The valve must cover the building's peak demand at the available pressure and allowable pressure drop, from the manufacturer's capacity chart.

Each valve size has a rated flow capacity published by the manufacturer. Undersizing starves equipment; an oversized valve costs more than it needs to. The valve also has to be the certified type for the jurisdiction, which in California means a seismic valve certified to Referenced Standard 12-16-1.

Sizing Steps

Identify the gas pipe size at the meter outlet, where the valve will be installed.
Determine the building's total connected gas load (the sum of appliance and equipment input ratings) and its peak demand.
Select a certified valve whose pipe connection and rated capacity cover that pipe size and demand.
For a building with more than one meter, repeat per meter.
Confirm the orientation the listing requires and a location that stays reachable for reset.

Size Reference

Valve size generally follows the gas pipe size at the meter. Use this as a starting point, then confirm against the manufacturer's rated capacity for your demand:

Gas pipe at meter	Typical valve size	Typical buildings
3/4 in to 1-1/4 in	3/4 in to 1-1/4 in	Single-family, small units
1-1/2 in to 2 in	1-1/2 in to 2 in	Small multifamily, light commercial
2 in to 4 in	2 in to 4 in	Restaurants, mid-size commercial
4 in to 8 in	4 in to 8 in	Large commercial, industrial, central plant

Multi-Meter Buildings

Apartment complexes, mixed-use projects, and campuses often have several gas meters. Each metered service typically needs its own valve, sized to that service, so a single property can call for a mix of sizes and a meaningful valve count. Plan one valve per meter unless your jurisdiction directs otherwise, and total the quantities by size when you request a quote.

Installation Notes

Mounted downstream of the meter, in the orientation the listing requires.
Located where it stays reachable to reset after a triggering event.
Larger valves are heavier and may need support at the connection.
Installed by an appropriately licensed contractor on a permit, with inspection.

Confirm before ordering: a valve sized only to the pipe can still be wrong if the gas demand is high. When the load is significant, confirm the size against the manufacturer's rated capacity, not the pipe size alone.

What We Need to Quote

To quote a commercial order, send the gas pipe size at each meter, the gas demand in CFH or BTU per hour if you have it, the number of meters, the building type, and the city or jurisdiction. With that we can match certified valves and price the order.

Quoting a commercial or multi-meter order?

Send pipe size, gas demand, and meter count, and we'll match California-certified valves and price the order. Typical turnaround: one business day.

or call 714-248-6555 · email partners@usmadesupply.com

Frequently Asked Questions

How do I know what size seismic gas valve I need?

It matches the gas pipe size at the meter and the building's peak gas demand in CFH or BTU per hour. A licensed contractor or the manufacturer's capacity chart confirms the size. Send us the pipe size and demand and we will match a certified valve.

Do commercial buildings need a different valve than homes?

The same idea applies, just in bigger sizes. Homes are usually 3/4 inch to 1-1/4 inch, while commercial and multifamily buildings often run 2 inch to 8 inch because the gas load is larger.

Does each gas meter need its own valve?

Typically yes. A building with more than one metered gas service usually needs a valve at each meter, sized to that service.

What information do you need to quote a commercial order?

The gas pipe size at each meter, the total gas demand if known, the number of meters, the building type, and the city. With that we can match certified valves and price the order.