Best Nitrogen Regulators for HVAC
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Top pickUniweld RHP400Check price
Nitrogen does two jobs on an HVAC install: it flows through the line set at a low rate while you braze, so the inside of the copper does not scale, and it pressurizes the circuit for a leak and strength test. A regulator that does both needs a pressure range high enough for the test, and fine enough control for the purge.
Quick answer: our top picks
- Best for pressure testingMid-rangeUniweld RHP400 Nitrogen Regulator20 to 400 psi delivery, piston-actuated seat, steel case, T-handle
- Best for brazing purgeMid-rangeWestern Enterprises VN-500 Nitrogen Purging RegulatorRegulator and flowmeter in one, with preset purge and braze flow rates
- Best value with lifetime warrantyMid-rangeSUA Nitrogen Gas Regulator SMP400Solid brass, CGA-580 inlet, lifetime warranty
- Best for high-pressure testsMid-rangeUniweld RHP800 Nitrogen Regulator0 to 800 psi delivery with a piston design and gauge boots
Comparison at a glance
| Product | Best for | Delivery pressure | Flowmeter | Price tier | |
|---|---|---|---|---|---|
| Top pickUniweld RHP400 Nitrogen Regulator | Pressure testing and purging | 20 to 400 psi | No | Mid-range | Check price |
| Western Enterprises VN-500 | Frequent brazing | Preset 500 psi test | Yes, 25 to 35 CFH purge | Mid-range | Check price |
| SUA Nitrogen Gas Regulator SMP400 | Budget, lifetime warranty | 20 to 400 psi | No | Mid-range | Check price |
| Uniweld RHP800 Nitrogen Regulator | High-pressure testing | 0 to 800 psi | – | Mid-range | Check price |
This guide covers four regulators. A flowmeter regulator and a pressure regulator are different tools, so decide which job matters most.
How to choose a nitrogen regulator
- Delivery pressure range: pressure testing needs a regulator that goes to at least 400 to 500 psi, purging needs a low, steady flow
- Flow control: a regulator with a flowmeter makes a consistent brazing purge easier
- Inlet connection: standard nitrogen cylinders use CGA 580
- Gauge protection: rubber boots and steel cases survive a truck
- Outlet fitting: 1/4 in flare hoses are standard on HVAC gauge hoses
Pressure regulator or flow regulator
A standard regulator controls outlet pressure. It is the right tool for pressure testing a line set, and it works for purging if you set a low pressure and leave the pressure gauge as your guide. A regulator with a flowmeter sets purge flow in cubic feet per hour. The Western Enterprises VN-500 lists preset purge flow of 25 to 35 CFH and braze flow of 3 to 6 CFH. Consistent flow is easier to repeat from job to job.
Whichever you choose, check the inlet. Standard nitrogen cylinders use a CGA 580 connection. Of the four here, the Uniweld regulators and the SUA list CGA-580 inlets. Confirm the inlet on the VN-500 before buying.
The nitrogen regulators in detail
Best for: Techs who need a durable regulator for pressure testing and purging.
- Delivery pressure 20 to 400 psi; nitrogen
- Inlet CGA-580 by male flare; 1/4 in nominal size
- Single-scale 2 in gauge with rubber boots
- Piston-actuated seat; steel case with polycarbonate lens; T-handle
- Porous metal inlet filter and fine mesh screen
Why it stands out
- Piston-actuated seat and steel case
- Inlet filter protects the seat
- T-handle makes adjustments easy with gloves
Keep in mind
- Confirm maximum inlet pressure and flow before buying
- No flowmeter; flow has to be set by feel or gauge
It has no flowmeter, so flow is set by feel or by gauge.
Best for: Techs who braze often and want a preset purge flow.
- Regulator and flowmeter in one unit
- Preset purge flow 25 to 35 CFH; preset braze flow 3 to 6 CFH
- Preset 500 psi test pressure
- 1/4 in SAE male flare outlet; brass
- Cylinder content gauge; hand-tight cylinder connection
Why it stands out
- Preset purge and braze flow rates
- Brass body
- Installs with no tools
Keep in mind
- Confirm the inlet connection before buying
Confirm the inlet connection before buying.
Best for: Pressure testing and purging on a budget with a lifetime warranty.
- Solid brass; two 2 in gauges with rubber protectors
- CGA-580 inlet; 1/4 in male flare outlet
- Delivery pressure 20 to 600 psi in the bullets; the item details list 400 psi maximum
- Maximum inlet pressure 3,000 psi; for nitrogen, argon and helium
- Lifetime warranty, so confirm the terms with the seller
Why it stands out
- Brass body
- Lifetime warranty
- Fits 1/4 in flare hoses
Keep in mind
- Maximum delivery pressure is published as both 600 psi and 400 psi, so confirm before buying
The listing shows two maximum delivery pressures, 600 psi and 400 psi. Plan around 400 psi.
Best for: Techs who pressure test at higher pressures than a 400 psi regulator allows.
- 0 to 800 psi delivery pressure
- CGA580 inlet and 1/4 in. male flare outlet
- 2 in. gauges with rubber boots
- Brass piston design with a self-reseating relief valve
- Brass T-handle with a stainless adjusting screw
Why it stands out
- 800 psi delivery range
- Piston design with gauge boots
Keep in mind
- The relief valve is not designed to protect the downstream system
The RHP800 delivers 0 to 800 psi, so it covers higher-pressure tests than the 400 psi regulators. It has a CGA580 inlet and a 1/4 in. male flare outlet. Its relief valve is not designed to protect the downstream system, so do not use it as a safety device.
Regulators not listed here
The Victor Edge ESS32-PFH-580, a pressure-flow hybrid purge regulator, and flow-gauge regulators from Harris and Uniweld with built-in flowmeters are worth a look, but we do not have verified listings for them. For leak finding after the pressure test, see our leak detector guide. Always secure the cylinder, and use a regulator rated for the pressure you set.
Still deciding?
Best for pressure testing: Uniweld RHP400 Nitrogen Regulator. 20 to 400 psi delivery, piston-actuated seat, steel case, T-handle.
Frequently asked questions
Why use nitrogen when brazing?
A low nitrogen flow inside the tube keeps oxygen out, which prevents scale from forming inside the line set. The Western Enterprises VN-500 presets purge flow at 25 to 35 CFH and braze flow at 3 to 6 CFH.
What pressure do I pressure test at?
Follow the equipment manufacturer's instructions. The Uniweld RHP400 delivers 20 to 400 psi, and the Western VN-500 is preset to a 500 psi test pressure.
Can I use an oxygen or acetylene regulator on a nitrogen cylinder?
No. Use a regulator made for nitrogen with the correct CGA fitting. Nitrogen cylinders use CGA 580, which is the inlet listed for the Uniweld RHP400.
Do I need a flowmeter?
It is not required for pressure testing, but a flowmeter helps hold the low flow rate recommended for brazing purges. The Western VN-500 combines the regulator and flowmeter.
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Sources
Specifications and product details were checked against these sources:
