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Spotlight on Maxitrol 325-L Line Pressure Regulators – 2 PSI

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Spotlight On Maxitrol 325-L Line Pressure Regulators – 2 PSI

Historically, people used appliance regulators for line pressure regulation. There is a new and revised standard that dictates that appliance regulators can no longer be used as line pressure regulators. The Maxitrol 325 Series regulators are ANSI-certified as line regulators for pilot applications or main burners with maximum inlet pressures of 5 PSI.

The ‘’L’’ line of the 325 series includes five line pressure-certified regulators meant to supply pressure to downstream appliances that already have regulators. Below is a detailed description of the Maxitrol 325-L pressure regulators for 2 PSI systems to guide your purchase.

What Type of Regulators Are They ?

Appliances like water heaters, furnaces, stoves, and fireplaces are often fueled by natural gas. This gas is distributed in lines with copper or corrugated stainless-steel tubing at 2-5 PSI (13.5 kPa). The 325-L Series from Maxitrol reduces gas pressure to the rated range for your device. The line pressure regulators certified for an inlet pressure of 2 PSI work for outlet pressure ranges of 7-11 inches WC.

The Maxitrol 325-L line pressure regulators for 2 PSI systems have lever-acting designs. Their regs are meant for corrugated stainless steel tubing (CSST), steel/black iron, or semirigid copper pipes. These regulators will deliver reliable and consistent positive dead-end lockup that can precisely control from pilot to full downflow.

You might wonder what dead-end lockup in a 325-L line pressure regulator is. When you shut down your device, its regulator’s downstream pressure will try to equalize its upstream gas pressure. The regulator will assume a fully-closed position with an increased outlet pressure and a surpassing of its set point pressure. As the downstream pressure rises over the specified point pressure, this increases the sealing force of the valve to the valve seat. The 325-L line pressure regulator’s dead-end lockup capability stops the equalization of outlet and inlet pressures and maintains outlet pressures that are slightly above the specified points under static conditions.

325-L Line Pressure Regulator_Lever_Acting_Cut Out

Cutaway drawing for Maxitrol 325-L (Image Source: Maxitrol)

Where Are They Used ?

The Maxitrol 325-L line pressure regulators for 2 PSI systems are used in industrial, commercial, and residential applications. The regulator gives your systems a ‘’break’’ where a new pressure design can regulate downstream system parameters. A plumbing engineer has no control over pressure regulation upstream of a pressure-regulating station. However, the engineer should confirm with a natural gas supplier the conditions that are expected at the inlet to an appliance.

The Maxitrol 325-L will be installed between an appliance regulator and a service regulator. The regulator is used in applications where the pressure of the gas supply exceeds that of the maximum allowed on the inlets of the appliances being supplied. The Maxitrol 325-L line pressure regulator is also often used where there is an expected pressure drop between an appliance and a service regulator.

For Which Types of Gas Are They Suitable ?

The Maxitrol 325-L line pressure regulators are used for manufactured, mixed, liquefied petroleum and LPG-air mixtures. One of the important considerations when picking a line regulator is the fluid type in your application. The formula for properly sizing a regulator will be affected by the fluid or gas type you are using. The liquid or gas also affects the seat and diaphragm materials that are compatible with them.

Maximum Individual Load and Capacities of Maxitrol 325-L Regulators

The CSA-certified rated inlet pressure for the Maxitrol 325-L regulator is 2 PSI, while the outlet pressure is 7’-11’’ w.c. The emergency exposure limit for the inlet side only is 65 PSI.

The maximum individual load denotes the rating of the largest single appliance that can be served by the regulators for 2 PSI systems. As for the capacity, it expresses the total load of multiple appliances combined.

Maxitrol 325-L Line Pressure Regulators – 2 PSI
Maximum Individual Load and Capacity per Model Table

Maxitrol 325-L Pressure Regulators 2 PSI Table

Mounting Options and Installation

The Maxitrol 325-L line pressure regulator for 2 PSI supports multi-positional mounting. Nonetheless, your regulator should be mounted horizontally when using a vent-limiting device. Mounting it in any other position will make the vent limiter’s ball check roll into a limiting/closed position, so the regulator might not work correctly.

The vent limiter used with the Maxitrol 325-L regulates gas flow from an atmospheric diaphragm chamber to the environment in case a diaphragm ruptures. Besides a vent limit, other overpressure protection devices for your line regulator include an overpressure relief device, an overpressure shutoff device, and a monitoring regulator.

What Is Imblue Technology ?

The Maxitrol 325-L line pressure regulator is available with Imblue technology. This is an anodized coating to increase the corrosion resistance of your Maxitrol regulator while providing an extra protection layer against harsh outdoor elements. The technology is best used for regulators that will be used in places that can make aluminum oxidize. These include northern climates with salted roads for winter, water treatment plants, coastal areas, and swimming pools.


The standard for certifying line pressure regulators is ANSI Z21.80/CSA 6.22. Maxitrol is in compliance with this standard for the production of its 325-L series line pressure regulators. With the implementation of the ANSI Z21.80/CSA 6.22, you should not use an appliance regulator as a line pressure regulator. Thankfully, the 325-L line pressure regulators are also certified under ANSI Z21.18 as appliance regulators. This means you will be getting two devices for the price of one.

From the information above, you now understand that Maxitrol 325-L line pressure regulators for 2 PSI systems are lever-acting devices for residential, industrial, and commercial use. They are used with CSST, semirigid copper, and steel/black iron pipes for manufactured, mixed, liquefied petroleum and LPG-air mixtures. These line pressure regulators are certified by the ANSI Z21.80/CSA 6.22 and ANSI Z21.18 and can be ordered with Imblue technology to increase corrosion resistance and add extra protection when used in outdoor applications.

Norgas Controls is pleased to offer the Maxitrol 325-L series gas regulators as part of our line and service regulators assortment. We also offer the 325-L Series with overpressure protection devices for 2 psi piping systems. Contact our experts for any questions regarding this product or any other natural gas regulator.

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