Maxitrol Company · Founded 1946 · Southfield, Michigan · "Maximum Control" · International Leader in Gas Pressure Regulators

Maxitrol Gas Pressure Regulators,
Modulating Systems & Safety Devices

Memphis Control Center stocks Maxitrol gas pressure regulators -- the industry standard for commercial and industrial gas-fired equipment. 325 Series lever acting appliance regulators (100,000 to 4,450,000 BTU/hr, 3/8" to 2" NPT). 325-L Series line pressure certified regulators (ANSI Z21.80/CSA 6.22 -- required for 2-PSI and 5-PSI gas systems). RV Series poppet appliance regulators (RV47, RV48 for main burner and pilot load; RV91-2 at 7,500,000 BTU). Selectra modulating systems for unit heaters, rooftop units, and infrared heaters (A1014R amplifier, TS114 discharge sensor, M411 modulating valves). 210 Series high-capacity regulators up to 26,000,000 BTU. A broad Maxitrol product selection available at Memphis Control Center. Family-owned, serving Memphis since 1967.

Browse All Maxitrol Products Call (901) 458-2000
325 Series · 325-L Line Pressure Certified RV Series Poppet Regulators Selectra Modulating Systems 210 Series High-Capacity Family-Owned Since 1967
Industry Standard Since 1946Maxitrol's Straight-Thru-Flow regulator design, patented in 1948, was the first significant improvement in gas regulator design in over a century. That innovation is the foundation for the industry standard regulators gas technicians specify today
Appliance vs. Line Pressure -- We Can HelpThe 325 (no "L") is an appliance-only regulator. The 325-L is certified for line pressure service. Specifying the wrong type is a code violation. Call (901) 458-2000 and we will confirm the correct Maxitrol for your application
Selectra Modulating SystemsMaxitrol Selectra systems modulate gas flow to hold a constant discharge air temperature on unit heaters and rooftop units, reducing energy use vs. on/off cycling. A1014R, TS114, M411 modulating valves -- all available
Same-Day ShippingMaxitrol regulators ship same day from Memphis, TN -- free. Call (901) 458-2000 with your pipe size, inlet pressure, required outlet pressure, and BTU capacity and we will identify the correct model
Maxitrol -- "Maximum Control" since 1946. In 1946, Frank Kern Jr. purchased the Detroit Regulator Company in Detroit, Michigan -- a small machine shop producing gas pressure regulators, model airplane engines, and serving the local auto industry. In 1948, the company received a patent for the Straight-Thru-Flow (STF) regulator design -- the first significant improvement in gas pressure regulator design in more than a century. The new regulator was named Maxitrol, short for Maximum Control. The STF design allowed gas to flow straight through the regulator without changing direction, reducing frictional resistance and dramatically increasing capacity at low inlet pressures -- a fundamental advantage for commercial and industrial applications. In 1953 the company officially became Maxitrol Company, and in 1954 introduced the poppet design regulator for main burner and pilot load applications. In 1959 Maxitrol developed the Selectra electronic gas flame modulation system, bringing proportional temperature control to gas-fired heating equipment. The company's headquarters moved from Detroit to Southfield, Michigan in 1960, where it remains today. By 1975 US production had reached 20 million regulators. Maxitrol expanded into Europe in 1965 and now has its European headquarters in Thale, Germany, with manufacturing in both Southeast Michigan and Germany and offices in Senden, Germany and Abercynon, UK. Over the past decade Maxitrol has filed more than 60 patents in 25 countries. Source: maxitrol.com/75-anniversary/ and LinkedIn.
Critical: Appliance Regulators vs. Line Pressure Regulators -- The Maxitrol 325 series without "L" in the model number (325-3, 325-5, etc.) is an appliance-only regulator certified to ANSI Z21.18/CSA 6.3. It cannot legally be used as a line pressure regulator ahead of other appliances. If your gas system operates at 2 PSI or 5 PSI (common in commercial buildings), you need a 325-L series regulator (325-3L, 325-5L, etc.) certified to ANSI Z21.80/CSA 6.22. Maxitrol marks line pressure certified regulators with a yellow sticker on the valve body. Call (901) 458-2000 if you are unsure which type you need -- using the wrong series is a code violation.

Maxitrol Product Series at Memphis Control Center

Maxitrol product series covering gas pressure regulation from residential appliances through large industrial burner systems. Contact us or call (901) 458-2000 with your pipe size, inlet pressure, required outlet pressure, and BTU load.

325 Series Lever Acting Appliance Regulators -- Most Popular Maxitrol Line

The Maxitrol 325 Series is the most widely specified gas pressure regulator in commercial and industrial HVAC. Lever acting design, aluminum housing, available in 3/8" through 2" NPT. Reduces supply gas pressure (typically 2 PSI line) to inches water column (W.C.) for appliance operation. Certified ANSI Z21.18/CSA 6.3 as appliance regulators. The suffix number after 325- indicates the body size and capacity (3 = smallest, up to 11 = largest). Without "L" in the model name = appliance regulator only -- cannot be used as a line pressure regulator. The 325-L series (with "L") carries the additional ANSI Z21.80/CSA 6.22 line pressure certification required for 2 PSI and 5 PSI gas distribution systems.

ModelMax BTU/hr (single appliance)Pipe SizesCertification
325 Series (Appliance Only -- ANSI Z21.18/CSA 6.3)
325-3-1/2100,000 BTU/hr3/8", 1/2"ANSI Z21.18 / CSA 6.3
325-3-3/8100,000 BTU/hr3/8"ANSI Z21.18 / CSA 6.3
325-5-1325,000 BTU/hr1/2", 3/4", 1"ANSI Z21.18 / CSA 6.3
325-9-22,250,000 BTU/hr1-1/2", 2"ANSI Z21.18 / CSA 6.3
325-L Series (Line Pressure Certified -- ANSI Z21.80/CSA 6.22)
325-3L-1/2140,000 BTU/hr3/8", 1/2"ANSI Z21.80 / CSA 6.22
325-5L425,000 BTU/hr1/2", 3/4", 1"ANSI Z21.80 / CSA 6.22
325-7AL1,250,000 BTU/hr1-1/4", 1-1/2"ANSI Z21.80 / CSA 6.22
325-9L2,250,000 BTU/hr1-1/2", 2"ANSI Z21.80 / CSA 6.22
325-11L4,450,000 BTU/hr2"ANSI Z21.80 / CSA 6.22

325 Series specs confirmed from Maxitrol 325 Series catalog (Cochrane Supply, State Supply, PEX Universe PDFs). BTU capacities at 1" W.C. pressure drop; 0.64 sp gr natural gas. Ambient temperature range for 325-L: -40°F to 205°F. All models available with vent limiters (12A09, 12A39, 12A49) for indoor installations.

3/8" to 2" NPT 100K to 4,450,000 BTU/hr Aluminum Housing NG · LP · Mixed Gas 325 = Appliance Only 325-L = Line Pressure Certified
RV Series Poppet Appliance Regulators (RV47/RV48) & Straight-Thru-Flow High-Capacity (RV91)

The Maxitrol RV Series covers two distinct regulator designs. RV12, RV20, RV47, RV48 are rubber-seat poppet appliance regulators for main burner and pilot load applications -- cooking appliances, barbecues, hearth products, residential water heaters, and pilot lines. Max inlet 1/2 PSI; outlet 1"-12" W.C.; sizes 1/8" to 3/4" NPT. Multi-poise mounting (any angle except "D" suffix models). RV47L includes an integral vent limiting orifice; RV48L includes an integral vent limiter. These are appliance-only regulators. RV52, RV53, RV61, RV81, RV91, RV111, RV131 are Straight-Thru-Flow (STF) high-capacity regulators for large commercial and industrial burner applications. The RV91-2 (2" NPT, 7,500,000 BTU/hr) is the most widely used large-capacity Maxitrol regulator.

ModelSizeCapacityTypeShop
RV Poppet Series -- Main Burner/Pilot Load
RV47L-3/8-4123/8"Pilot/main burnerPoppet · w/ vent orificeShop
RV47L-3/8-6103/8"Pilot/main burnerPoppet · 6-10" WC springShop
RV47L-3/8-133/8"Pilot/main burnerPoppet · 1-3" WC springShop
RV47L-3/8-483/8"Pilot/main burnerPoppet · 4-8" WC springShop
RV47LF-4L6-00081/2"30,000 BTU · 8" WC fixedPoppet · fixed outletShop
RV48-3/4-483/4"230,000 BTUPoppet · 4-8" WC springShop
RV48-1/2-131/2"Main burnerPoppet · 1-3" WC springShop
RV20VL-1/4-131/4"Pilot/main burnerPoppet · w/ vent limiterShop
RV STF Series -- High-Capacity Commercial/Industrial
RV91-22" NPT7,500,000 BTU/hrSTF · 3-6" WC spring · max 1 PSI inletShop
RV47/RV48: 1/8"-3/4" NPT Max Inlet 1/2 PSI (Poppet) ANSI Z21.18 / CSA 6.3 RV91-2: 2" · 7,500,000 BTU Rubber Seat · Aluminum Body NG · LP · Mixed Gas
Selectra Series Modulating Gas Control Systems -- Unit Heaters, Rooftop Units, Infrared Heaters

The Maxitrol Selectra modulating system (developed 1959, continuously refined since) modulates gas flow to commercial gas-fired heating equipment to hold a constant discharge air temperature -- eliminating on/off cycling, reducing energy consumption, and improving comfort. The system uses a discharge air temperature sensor (TS114) in the unit's air stream to signal the amplifier (A1014R), which in turn positions the modulating valve (M411) to deliver exactly the amount of gas needed for the required heat output. As the space warms and approaches setpoint, the modulating valve throttles back the gas -- holding a constant outlet air temperature rather than the extreme swing of on/off cycling. Used on unit heaters, rooftop heating units, and infrared radiant heaters in warehouses, manufacturing plants, aircraft hangars, and commercial spaces. The TD114 remote selector lets building operators adjust the discharge air temperature setpoint from a remote location.

PartDescriptionShop
A1014RUniversal Amplifier Selector -- Series 14 modulating system brainShop
TS114Discharge air temperature sensor · 55-90°F · mounts in air streamShop
TD114Remote selector-discharge air sensor · 55-90°F · operator adjustableShop
M411-1/2Modulating valve · 1/2" · Selectra Series 14/44Shop
M411B-1/2Modulating valve B-version · 1/2" · Selectra SeriesShop
M411W-1/2Modulating valve W-version · 1/2" · Selectra SeriesShop
R700-1Remote temperature selector · for Selectra modulating systemsShop
SR500W-1Selectra Remote 500W seriesShop
SC30Signal conditioner accessory for Selectra systemsShop

Source: Maxitrol Selectra Series 14 and 44 product catalog (confirmed from Carremm Controls TS144 listing); Maxitrol.com. TS114 = 55-90°F discharge air sensor for Series 14. A1014R = Universal Amplifier Selector compatible with Series 14 and other Selectra series. M411 modulating valve is the gas flow control element.

A1014R Amplifier TS114 · 55-90°F Sensor TD114 Remote Selector M411 Modulating Valve Unit Heaters · RTUs · Infrared Developed 1959
210 Series · Pakstat · RV48L & More High-Capacity Regulators, Process Controls, and Additional Series

The Maxitrol 210 Series are high-capacity appliance regulators for large commercial and industrial burner applications -- 1" through 3" NPT and beyond, with capacities up to 26,000,000 BTU/hr (210G-3). Used on industrial boilers, large commercial heating systems, and process burners. Pakstat Series (P14, P64) are process temperature controls for industrial temperature regulation -- P14A0318-903 covers 150-550°F, P64A0318-901 covers 50-250°F. RV48L and RV47L versions of the poppet series include an integral vent limiter for indoor installations where external venting is not practical.

ModelDescriptionShop
210 Series -- High-Capacity Appliance Regulators
210D-11" NPT high-capacity gas appliance regulatorShop
210E-22" NPT high-capacity gas appliance regulatorShop
210G-33" NPT · 26,000,000 BTU/hr · large industrial applicationsShop
220G-33" NPT high-capacity gas appliance regulatorShop
Pakstat -- Process Temperature Controls
P14A0318-903Pakstat Series 1 · 150-550°F process temperature controlShop
P64A0318-901Pakstat Series 2 · 50-250°F process temperature controlShop
Vent Limiters and Accessories
12A09Vent limiter / ball check for 325 series (required for non-vented indoor installation)Shop
210 Series: 1" to 3" NPT Up to 26,000,000 BTU/hr Pakstat: 50-550°F Process Vent Limiters: 12A09 / 12A39 / 12A49

How to Read a Maxitrol 325 Model Number

The Maxitrol 325 series model number encodes the body size, line pressure certification, pipe size, spring range, and accessories. Source: Maxitrol 325 Series catalog and Linc Energy Systems (lincenergysystems.com).

SegmentWhat It MeansExample
325Lever acting design series (all 325 regulators are lever acting)325-3L-1/2-12A09
-3 / -5 / -7A / -9 / -11Body size and capacity (3 = smallest / 11 = largest). Higher number = greater BTU capacity325-3L-1/2-12A09
L (after body size)Line Pressure certified (ANSI Z21.80/CSA 6.22). Without "L" = appliance-only regulator. This is the most critical distinction325-3L-1/2-12A09
-1/2 / -3/4 / -1 etc.Nominal pipe size (NPT connection size)325-3L-1/2-12A09
Spring suffix (e.g. 48, 412, 812)Spring range in inches W.C. (e.g. 48 = 4-8" WC outlet pressure, 412 = 4-12" WC). If no spring suffix, uses standard springRV47L-3/8-48
12A09 / 12A39 / 12A49Vent limiter type attached (required for indoor non-vented installation; replaces external vent pipe). Maxitrol marks certified vent limiters with a yellow tag325-3L-1/2-12A09
-LIM / -LIMLPFactory-installed limiter or LP version with limiter325-3L-1/2-LIMLP01
L (in RV series)In the RV poppet series, "L" indicates an integral vent limiting orifice (breather hole) in the valve cap -- different from the line pressure "L" in the 325 seriesRV47L-1/2-412

Maxitrol marks line pressure certified 325-L regulators with a yellow sticker on the valve body. Certified vent limiting devices carry a yellow tag. Source: lincenergysystems.com. If you have a model number and are not sure how to read it, call (901) 458-2000 and we will confirm the correct interpretation and confirm stock.

Most-Ordered Maxitrol Products

Browse all Maxitrol products →
325-3-1/2Lever acting · 1/2" · 100K BTU · appliance 325-3-3/8Lever acting · 3/8" · 100K BTU · appliance 325-5-1Lever acting · 1" · 325K BTU · appliance 325-3L-1/2Line pressure certified · 1/2" · ANSI Z21.80 325-9-2Lever acting · 2" · 2,250,000 BTU RV48-3/4-48Poppet · 3/4" · 230K BTU · 4-8" WC RV48-1/2-13Poppet · 1/2" · 1-3" WC · main burner RV47L-3/8-412Poppet · 3/8" · 4-12" WC · w/ vent orifice RV47LF-4L6-00081/2" · 30K BTU · 8" WC fixed outlet RV20VL-1/4-13Poppet · 1/4" · w/ vent limiter · 1-3" WC RV91-2STF · 2" · 7,500,000 BTU · industrial A1014RSelectra Universal Amplifier · Series 14 TS114Discharge air sensor · 55-90°F · Selectra TD114Remote selector-discharge air · 55-90°F M411-1/2Modulating valve · 1/2" · Selectra 210G-3High-capacity · 3" NPT · 26,000,000 BTU 210D-1High-capacity · 1" NPT 210E-2High-capacity · 2" NPT P64A0318-901Pakstat Series 2 · 50-250°F process All Maxitrol →Browse all Maxitrol products
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Frequently Asked Questions -- Maxitrol Gas Regulators & Modulating Systems

Common questions from gas technicians, mechanical engineers, HVAC contractors, and facility managers about Maxitrol gas pressure regulators and Selectra modulating systems. Contact us or call (901) 458-2000 with your pipe size, inlet pressure, outlet pressure, and BTU load.

What is the difference between the Maxitrol 325 and 325-L series?

The critical difference is line pressure certification. The 325 without "L" (325-3, 325-5, 325-7A, 325-9) is an appliance-only regulator certified to ANSI Z21.18/CSA 6.3 -- it reduces gas pressure at the appliance connection and cannot legally be used as a line pressure regulator in 2-PSI or 5-PSI systems. The 325-L series (325-3L, 325-5L, 325-7AL, 325-9L) carries the additional ANSI Z21.80/CSA 6.22 line pressure certification -- required for commercial buildings with 2-PSI or 5-PSI gas distribution. Maxitrol marks line pressure certified regulators with a yellow sticker on the valve body. Using an appliance-only 325 as a line regulator is a code violation. Call (901) 458-2000 if unsure which type you need. Source: lincenergysystems.com; Maxitrol 325 Series catalog.

What is the Maxitrol Selectra modulating system and how does it work?

The Maxitrol Selectra system (developed 1959 by Maxitrol) modulates gas flow to hold a constant discharge air temperature on gas-fired unit heaters, rooftop units, and infrared heaters -- eliminating energy waste and comfort swings from on/off cycling. The TS114 discharge air sensor (55-90°F) mounts in the heated air stream and sends a signal to the A1014R amplifier, which positions the M411 modulating valve to deliver exactly the gas flow needed. As discharge air temperature approaches setpoint, the modulating valve throttles back gas flow rather than switching off. The TD114 remote selector allows setpoint adjustment from a remote location. Used in warehouses, factories, aircraft hangars, and commercial buildings. Source: Maxitrol Selectra Series 14 and 44 catalog; maxitrol.com/75-anniversary/.

What does the "L" in the Maxitrol RV47L or RV48L mean?

In the Maxitrol RV poppet series, "L" means an integral vent limiting orifice (a calibrated breather hole) is built into the valve cap -- this is different from the "L" in the 325-L series (which means line pressure certified). The RV47L and RV48L include the vent limiting orifice as the regulator breather, making them suitable for indoor installations without an external vent pipe. Without the "L", the regulator vent port must be piped outdoors or a separate field-installed vent limiter must be added. Source: SupplyHouse RV47L product description; Carremm Controls RV series specs.

How do I select the right Maxitrol 325 regulator?

You need four parameters: (1) Pipe size (NPT connection size), (2) Inlet pressure (2 PSI for commercial line pressure; 7-14" W.C. for low-pressure residential), (3) Required outlet pressure in inches W.C. (3.5-7" W.C. for most appliances, or per equipment nameplate), (4) Total BTU load (sum of all appliances served). The body suffix (3, 5, 7A, 9, 11) determines capacity. For 2-PSI or 5-PSI gas systems, use a 325-L series regulator. For low-pressure residential systems, the standard 325 appliance regulator serves the appliance connection. Call (901) 458-2000 with these four parameters and we will confirm the correct Maxitrol model.

When are vent limiters (12A09, 12A39, 12A49) required on a Maxitrol regulator?

Maxitrol regulators have a vent port that allows small amounts of gas to escape during operation -- normal by design. In outdoor installations, the vent is left open or protected with a vent protector. In indoor installations, the vent must either be piped outdoors or an approved vent limiting device must be installed on the vent port. Vent limiters 12A09, 12A39, 12A49 screw onto the vent port and limit any release to a very small calibrated orifice -- small enough to prevent dangerous indoor gas accumulation while allowing the regulator to breathe. Required by the International Fuel Gas Code (IFGC) and NFPA 54 for indoor gas regulators that are not vented to the exterior. Maxitrol marks certified vent limiters with a yellow tag. Source: Maxitrol 325-L catalog; lincenergysystems.com.

Who is Maxitrol and where are they based?

Maxitrol Company is a privately held manufacturer of gas pressure regulators, electronic gas modulation systems, combination gas control valves, and gas safety devices. In 1946, Frank Kern Jr. purchased Detroit Regulator Company in Detroit, Michigan. In 1948 the company patented the Straight-Thru-Flow (STF) regulator design and named it Maxitrol (Maximum Control). In 1953 the company was renamed Maxitrol Company and expanded throughout Michigan. Maxitrol's worldwide headquarters is in Southfield, Michigan, with European headquarters in Thale, Germany and manufacturing in both locations. More than 60 patents in 25 countries filed in the past decade. Source: maxitrol.com/75-anniversary/; LinkedIn.

Need a Maxitrol Regulator or Modulating System Component?

Call us with your pipe size, inlet pressure, required outlet pressure, and BTU load and we will identify the correct Maxitrol model. Same-day shipping on stocked products from Memphis, TN.

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For emergencies, outside of business hours, call #901-604-7069