SMP400 – NITROGEN REGULATOR

A nitrogen regulator used for brazing purge, pressure testing, and leak checking on HVAC systems. Connects to standard nitrogen tanks via CGA580 fitting with a 1/4″ output. Every tech needs one — nitrogen purge during brazing prevents scale buildup inside copper lines.

Specs: CGA580 inlet connection, 1/4″ output, adjustable output pressure, for nitrogen tanks

Replaces: 0781-0775, 11336002, 194200, 20-0012-08, 601-2030, SMP400, SMPN, TME8708

Fits: Standard nitrogen tanks with CGA580 valve. Used for HVAC brazing purge, pressure testing, and leak detection.

In stock at Open To Public HVAC Parts in Dallas. We test parts at the counter before you buy. Call or text (214) 340-9421.

Specs

• TypeGas regulator

Cross-reference numbers

This part replaces the following OEM and aftermarket numbers:

• 0781-0775
• 11336002
• 194200
• 20-0012-08
• 601-2030
• SMPN
• TME8708
• UNIWELDRHP400

Not sure if your number matches? Call (214) 340-9421 or bring the old part in — bench-testing is free.

Fits these models

• UNIWELDRHP4000-400PSIEQUIVALENT

Do I need to purge with nitrogen while brazing?

On any refrigerant line, yes. Brazing copper in still air forms cupric oxide scale on the inside of the tube. That scale breaks loose later and plugs the metering device or damages the compressor. Flow a low nitrogen purge through the line the whole time you have heat on it.

Oxy-acetylene or air-acetylene?

Air-acetylene is enough for most residential line work and is simpler and safer to handle. Oxy-acetylene runs much hotter, which you want on larger tubing or dirty conditions. If you are learning, air-acetylene is the friendlier place to start.

Which rod do I use on copper to copper?

A phosphorus-bearing rod is self-fluxing on copper to copper, so no flux is needed. Copper to brass or copper to steel needs a silver-bearing rod AND flux. Using a phos rod on steel will crack.

Do I need a flame blanket?

Anywhere you are brazing near framing, insulation or drywall - which in a real house is almost everywhere. A flame-resistant blanket is a lot cheaper than a callback with a fire truck in it.

Are regulators interchangeable between oxygen and acetylene?

No. They have different threads and different pressure ranges on purpose, and acetylene fittings are left-hand threaded. Never force a fitting and never use oil or grease anywhere near an oxygen regulator.

Do you stock the gas too?

We carry torch kits, regulators, tips and supplies at 10226 Plano Rd, Suite 104 in Dallas. Ask at the counter about gas.