Skip to content
Explore our extensive range of high-quality brass fittings and fitting kits, including push-to-connect (PTC) fittings, Schrader valves, and more. Designed for seamless integration with various air systems, our fittings are available in sizes ranging from 1/8" to 3/4" NPT. Whether you're setting up or maintaining air suspension, onboard air systems, or industrial pneumatic applications, our durable and reliable fittings ensure optimal performance and leak-free connections.
Frequently Asked Questions
Why does my 1/2 inch fitting measure 0.84 inches?
Because NPT sizes are nominal pipe sizes, named for the pipe bore they fit, not for what the fitting measures across the threads. Every NPT size measures bigger than its name on a tape: 1/8 inch NPT measures about 0.405 inches across the male threads, 1/4 inch is 0.540, 3/8 inch is 0.675, 1/2 inch is 0.840, and 3/4 inch is 1.050. So a 1/2 inch fitting that tapes out to 0.84 inches is labeled correctly. Our NPT thread guide has the full chart with threads per inch.
What is the difference between NPT and PTC fittings?
NPT is the thread standard: tapered pipe threads that wedge tighter as you turn them, used on tank ports, compressors, and most air-system components. PTC means push to connect: instead of threading, you push the air line straight into the fitting and an internal collet grips it while an o-ring seals it, and pressing the release ring frees the line. Most air systems use both, NPT where the fitting meets a port and PTC where the air line meets the fitting.
What size fittings does my air system need?
Match the fitting to the port it's going into, not to the air line. Check the spec sheet for the port's NPT size, or measure the port's male thread across the outside and compare it to the chart in our NPT thread guide: 0.405 inches measured means 1/8 NPT, 0.540 means 1/4, 0.675 means 3/8, 0.840 means 1/2. If you're plumbing a whole tank, our fitting kits bundle the right sizes by tank, from 2-gallon single-compressor up to 20-gallon quad-compressor setups.
What does a check valve do in an air system?
A check valve lets air flow one direction only. It sits between the compressor and the tank, so stored air can't bleed backward through the compressor head when it shuts off. That keeps the tank holding pressure while the system rests and lets the compressor restart without fighting the full tank pressure that would otherwise sit on its head. If your tank loses pressure whenever the compressor stops, a failed check valve is one of the first things to test.
What is a safety blow-off valve and which one do I need?
A blow-off valve is the fail-safe: if the pressure switch ever sticks and the compressor keeps pumping, the valve pops open at its rated pressure and vents the excess instead of letting it build. Pick the rating one step above your system's operating pressure. We carry four: 150 PSI for 90 to 120 PSI systems, 175 PSI for 150 PSI systems, 205 PSI for 175 PSI systems, and 235 PSI for 200 PSI systems.
Do NPT fittings need thread sealant?
Yes. NPT threads are tapered and seal by wedging metal against metal, and thread sealant fills the tiny spiral gap that remains, so wrap the male threads with sealant tape or paste before installing any NPT fitting. Skip it and the joint will usually weep air slowly, which shows up as a tank that bleeds down overnight. PTC connections are the opposite: the o-ring does the sealing, so the air line pushes in dry, no tape anywhere near it.