Flojet 01810003C Adapter, 3/8" PEX x 1/2" NPT
The Flojet 01810003C is a genuine push-fit plumbing adapter joining 3/8" ID PEX tubing to a 1/2" NPT thread. It lets a quick-connect tubing run terminate at any standard NPT port — a pump inlet or outlet, a tank fitting, a valve body or a manifold.
NPT is a tapered thread, and that tapered form is worth understanding because it is the source of most fitting failures. The seal is made by the flanks of the thread wedging together as the joint tightens, which means the thread itself has to deform slightly. In brass against brass that is fine. In plastic it means there is a narrow band between not tight enough to seal and tight enough to split the female fitting, and the band is narrower than most people assume. Fit it firm with sealant, then stop.
On the tubing side there is no such judgement to make: the tube pushes in and locks, sealing against an internal O-ring. Cut the tube square and clean, push it fully home, and give it a gentle pull to confirm it has locked. Support the tubing with a clip near the fitting so the joint is not carrying the weight of a water-filled run.
Key Features
- Genuine Flojet (Xylem) plumbing fitting — part of the quick-connect system
- Push-fit connection for 3/8" ID PEX tubing — no clamps, crimps or special tools
- 1/2" NPT thread for standard pump, tank and valve ports
- Internal O-ring seal on the tube side, made correctly every time
- Assembles by hand in confined spaces
Applications
- Fresh water plumbing systems built in 3/8" PEX tubing
- Terminating a tubing run at an NPT pump port or tank fitting
- Connecting to valves, manifolds and filter housings
- Replacing barbed joints that have begun to seep
- Marine, RV and mobile potable water systems
Specifications
- Brand: Flojet (Xylem)
- Manufacturer Part Number: 01810003C
- Part Type: Push-fit adapter fitting
- Tube Connection: 3/8" ID PEX, push-fit
- Thread Connection: 1/2" NPT
- Condition: New
Frequently Asked Questions
Q: How tight should an NPT thread into plastic go?
Hand tight plus a short turn with a spanner, and no more. NPT seals on the thread flanks, so extra torque mostly goes into stressing the female fitting rather than improving the seal.
Q: Tape or paste on the threads?
Either works. Tape should be wound in the direction the thread turns so it does not unwind as you screw it in, and kept back from the first thread so shreds cannot get into the water.
Q: Why is my new fitting weeping at the thread?
Usually too little sealant, or a thread that was cross-started and has damaged flanks. Back it out, inspect the first few threads, clean off the old sealant and start again by hand before touching a spanner.
Q: Can I mix these with other push-fit brands?
Stay within one system. Tube outside diameters and internal seal dimensions vary between manufacturers, and a joint that feels secure but is very slightly out of tolerance is a leak waiting for a cold night.
Not sure this is the right part? Send us a Picture of the pump plate on your pump and the CLR Marine team will confirm the correct part before you order.
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