Gas pressure regulators

The Maxitrol RV52 is the regulator I’d reach for on a single appliance. It scores 9.3, tied for the top of this page, and it has the most headroom of the 1/2 in. options here.

It’s a straight-thru-flow design. Maxitrol explains that a cone-shaped valve lets gas flow straight through without changing direction, which cuts friction and raises capacity at very low pressure differences. Maxitrol lists residential, commercial and industrial appliances as typical uses.

The capacity is clear in Maxitrol’s catalog: a CSA maximum of 450 CFH on 1/2 or 3/4 in. pipe, with 262 CFH at a 0.3 in. w.c. pressure drop and 478 CFH at 1 in. w.c.. Maxitrol’s own sizing example counts 2,500 CFH as 2,500,000 Btu/h, so 450 CFH is about 450,000 Btu/h of natural gas.

It’s certified to ANSI Z21.18/CSA 6.3 for gas appliance pressure regulators, rated for 1/2 psi inlet, with an emergency exposure limit of 3 psi and an ambient range of −40 to 205°F. The aluminum body mounts in any position.

This listing names the spring: 3 to 6 in. w.c., plated, which is the CSA-certified natural gas range Maxitrol lists for the RV52. Maxitrol also certifies orange 4–8 and blue 5–12 in. w.c. springs, so the same body covers other set points.

There are two limits. Straight-thru-flow regulators are non-lockup, which Maxitrol says suits main burner applications rather than holding pressure under no flow. And the 1/8 in. vent takes Maxitrol’s 12A04 vent limiting device as a separate part; with it fitted, Maxitrol says to mount the regulator upright.

Maxitrol’s sizing rule for this family is to keep the pressure drop under half of the available difference between inlet and outlet pressure. The sizer below applies it.

Maxitrol says service and installation must be done by a trained, experienced technician, following the appliance maker’s instructions and local codes. That’s how I’d treat it too.

The Maxitrol RV48L also scores 9.3, but it does a different job. It’s Maxitrol’s rubber seat poppet design, built for main burner and pilot loads, and the L means a vent limiting orifice is built into the breather hole.

That built-in limiter has a cost that the listing doesn’t mention. Maxitrol’s capacity table for the RV48 gives a maximum individual load of 40,000 Btu/h with the fixed orifice, against 160,000 Btu/h with a ball check vent limiter. Maxitrol’s own sizing example picks the RV48 without the L for a 150,000 Btu/h burner.

So the RV48L is right for small appliances rated 40,000 Btu/h or less each. Its total range of regulation at 3/4 in. is 250,000 Btu/h, with 150,000 Btu/h at a 0.3 in. w.c. drop, so it can feed several small loads.

Poppet regulators lock up. Maxitrol describes the RV47 and RV48 as suitable for pilot flow applications, and its glossary explains dead-end lockup: when the appliance shuts off, the regulator closes and holds downstream pressure within ANSI/CSA limits.

It’s certified to ANSI Z21.18/CSA 6.3, rated for 1/2 psi inlet, with a 2.5 psi emergency exposure limit and a 0 to 225°F ambient range. Maxitrol publishes a dimension drawing for it, with a 2 in. swing radius, the smallest on this page.

The listing describes a 3/4 in. FPT natural gas regulator with a 3 to 6 in. w.c. outlet range. It also explains that 3/4 in. gas pipe measures about 1-1/16 in. outside, which is the opening you’ll see.

Watch for look-alikes. Several Amazon listings titled Maxitrol RV48L carry another brand in their brand field; I left those out. This one is listed under the Maxitrol brand.

As with every Maxitrol regulator, Maxitrol says a trained technician should install it, following the appliance maker’s instructions and local codes.

The Maxitrol RV53-1 scores 8.8. It’s the next size up in the same straight-thru-flow family as the RV52, with the same certification, pressures and spring choices.

Capacity is the reason to choose it. Maxitrol lists a CSA maximum of 690 CFH on 3/4 or 1 in. pipe, with 375 CFH at a 0.3 in. w.c. drop and 684 CFH at 1 in. w.c.. By Maxitrol’s own counting, that’s about 690,000 Btu/h of natural gas.

It’s certified to ANSI Z21.18/CSA 6.3, rated for 1/2 psi inlet, with a 3 psi emergency exposure limit and a −40 to 205°F ambient range. Maxitrol lists a minimum regulation of 20 CFH, so it suits a big burner rather than a trickle.

It loses half a point because the listing doesn’t say which spring is installed. Maxitrol’s CSA-certified springs for the RV53 are plated 3–6, orange 4–8 and blue 5–12 in. w.c.. Ask the seller, or check the spring color under the seal cap when it arrives.

Maxitrol publishes a dimension drawing with a 3.9 in. swing radius for the RV53, against 3.6 in. for the RV52, so leave a little more room around it on a crowded manifold.

Maxitrol gives the RV52 and RV53 a gas containment limit of 15 psi and notes that internal damage may occur at that pressure, one more reason they belong on house-pressure gas only.

Like the RV52 it’s non-lockup and takes the 12A04 vent limiting device as an add-on part, mounted upright when fitted.

Maxitrol’s rule for these regulators is to keep the pressure drop under half of the available differential. On a 1 in. line feeding one large appliance, the RV53 usually leaves the most room under that limit.

Maxitrol says installation and service are for trained technicians, following the appliance maker’s instructions and local codes.

The Maxitrol RV61-1-1/4 scores 8.8. It’s the biggest regulator on this page and the one to use when the load outgrows the RV53.

Maxitrol lists a CSA maximum of 900 CFH on 1 or 1-1/4 in. pipe, with 675 CFH at a 0.3 in. w.c. drop and 1,200 CFH at 1 in. w.c.. The listing calls it 2,500,000 Btu/h; Maxitrol’s catalog gives 900 CFH as the CSA maximum, so size it from the catalog.

It’s CSA certified for 1/2 psi inlet like the others, and Maxitrol tests the RV61 to 1 psi, with a 5 psi emergency exposure limit and a 25 psi gas containment limit. Maxitrol adds a rule: don’t use it where inlet pressure is more than 10 times the outlet pressure.

The spring choices are wider too. Besides the plated 3–6, orange 4–8 and blue 5–12 in. w.c. springs, Maxitrol lists a red 10–22 in. w.c. spring for the RV61, and certifies its 2–5 in. w.c. spring.

It loses half a point for a listing that doesn’t name the installed spring. Confirm it with the seller before you count on a set point.

Maxitrol’s dimension drawing gives it a 4.8 in. swing radius, the largest here. Its minimum regulation is 25 CFH, so it isn’t the right choice for a small single appliance.

Maxitrol makes the RV61 for 1 and 1-1/4 in. pipe; this listing is the 1-1/4 in. version. Like the rest of the family, Maxitrol rates it for natural, manufactured and mixed gases, LP and LP-air mixtures, with the right spring.

Like the rest of the straight-thru-flow line, it’s non-lockup and takes the 12A04 vent limiting device as a separate part.

Maxitrol says these regulators are for trained technicians to install and service, following the appliance maker’s instructions and local codes.