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Gas Orifice Sizes for Outdoor Gas Fire Pits: A Comprehensive Guide

This brief guide covers everything you need to know about using the correct gas orifice for your DIY gas fire pit. You’ll discover what a gas orifice is, how it differs between propane and natural gas, and finally, how to ensure you have the right one for your fire pit to operate safely and efficiently. 

What is a Gas Orifice?

A gas orifice is a small opening or hole that controls the flow of gas to a gas appliance or device. Gas orifices are usually made from brass or stainless steel, and come in a range of sizes to accommodate different types of gas fire pits and burners.

The size of the gas orifice is crucial for ensuring the proper operation and safety of a gas fire pit. If the orifice is too small, the gas fire pit may not light or produce the desired level of flames or heat. If the orifice is too large, it may result in a dangerous and uncontrollable flame. Therefore, it’s important to use the right size gas orifice for the BTU/hr. rating of your outdoor gas fire pit.

While the orifice is a separate part, it is typically integrated into another fitting. For example, the orifice is a part of the air mixer we sell for propane gas fire pit burners. Our natural gas fire pit burner connection kits also include an orifice. Each kit is sized according to the BTU/hr. rating of your burner. So, it is not likely you would ever need to purchase an orifice separately.

Is a Propane Orifice Different than a Natural Gas Orifice?

As you can see in the illustration to the right, the orifice size for natural gas is much larger than it is for propane when comparing burners with the same BTU/hr. rating.

That’s because propane and natural gas have different physical properties and require different flow rates. Natural gas requires a higher flow rate than propane, so a natural gas orifice has a larger hole. 

It takes 2.5 times more natural gas than propane to produce the same result. Propane generates 2,500 BTU/hr. per cubic foot of gas compared to 1,000 BTU/hr. per cubic foot of natural gas.

propane and natural gas orifice size comparison chart

Because of these differences, propane and natural gas orifices are not interchangeable and must be matched to the type of gas being used.

What’s the Difference Between a Gas Orifice and a Gas Regulator?

A gas orifice controls the flow of gas—how much gas is allowed to pass through the hole. It determines the size and intensity of the flame in a gas fire pit. 

The gas regulator controls the pressure of the gas flow—how fast the gas is allowed to pass through the appliance or device. It is usually connected to the gas tank or gas line. The regulator ensures gas pressure is at the proper level for the safe and efficient operation of the appliance. 

How are Gas Orifice Sizes Measured?

Gas orifice sizes are typically measured by the diameter of the hole size. It is expressed in either inches or millimeters, and it determines the flow rate of gas through the orifice. A larger diameter gas orifice allows for a higher flow rate of gas, while a smaller diameter restricts the flow. 

To determine the correct size gas orifice for your gas fire pit, you will need to know the flow rate of gas required by the fire pit. This is typically expressed in BTUs per hour. You can then refer to an orifice capacity chart to find the appropriate size gas orifice for your fire pit.

Using the Gas Orifice Capacity Chart

First, this chart is meant as a general reference. Depending on the configuration of the appliance, it may be difficult to access the part that contains the orifice and get a good look at it. Even if you do, it would be hard to measure. Some manufacturers etch the size of the part, but not all do. 

If you’re having a problem with your fire pit flame size, heat output, or control. This chart might come in handy as a troubleshooting tool. 

For instance, if you detach the air mixer and it is readily apparent without a measuring device that the hole is much smaller than the recommended size on the chart below, it’s likely that the air mixer (of which the orifice is a part) was incorrectly sized. 

To use the chart, find the BTU/hr. rating for your gas fire pit below and choose the column based on the type of gas you are using to find the size your gas fire pit requires. 

Propane and natural gas orifices are not interchangeable. Be sure to look at the correct column for the type of gas you are using.

Gas Orifice Capacity Chart

Burner BTU RatingPropane Orifice SizeNat. Gas Orifice Size
37k BTU1.85 mm2.65 mm
55k BTU2.30 mm3.78 mm
65k BTU2.49 mm4.30 mm
95k BTU4.20 mm5.56 mm

Give Us a Call

If you suspect an issue with the size of the orifice in your gas fire pit, reach out to the manufacturer or give us a call. We’re always happy to help you troubleshoot a problem.

Reach us Monday through Friday from 8 a.m. to 5 p.m. ET at 301-245-7755.

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