Pipe thread nomenclature

[F51]

Got me a new fancy whiz-bang genuine Racor dual fuel filter. The inlet and outlet ports are 3/4"-16 UNF. The hardware store doesn't have any hose barbs with that thread, only NPT. With my luck, I'm guessing I'll have to order the 3/8" hose barbs from Racor. Comments?

[2Hulls]

UNF is unified fine, as opposed to UNC which is unified coarse. NPT is pipe thread, which is tapered. Yes, you need to get a hose barb to fit the UNF thread in the filter. Good hardware stores should have these. Otherwise, go to McMaster Carr online. Good luck.

2 Hulls Dave

[Maine Sail]

Originally Posted by F51

Got me a new fancy whiz-bang genuine Racor dual fuel filter. The inlet and outlet ports are 3/4"-16 UNF. The hardware store doesn't have any hose barbs with that thread, only NPT. With my luck, I'm guessing I'll have to order the 3/8" hose barbs from Racor. Comments?

You will need an adapter... These filters take a UNF with o-ring...

Fittings For Racor

[leftbrainstuff]

You have two options for obtaining a leakproof seal on threads.

Tapered threads seal the thread but tend to be better suited to cheap rugged components like galvanised pipe. They require little skill to obtain a leakproof seal and are tolerant of people using a myriad of sealants.

Parallel threads require a flange seal or tapered seat seal. They are better for positioning outlets and work well with more 'petite, assemblies that take up the least amount of space. They are far less tolerant of grit and poor choice of sealants. Racor units are a precision engineered component so parallel thread fittings are appropriate.

Note that sealants don't seal either tapered or parallel fittings but they may avoid twisting and tearing flange seals and often aid disassembly.

There are many thread, seat and flange types and forms. The name brands are well engineered and have many decades of quality in mission critical applications.

I never mix and match and only buy name brands. Life is much simpler. Lowest cost or nearest supplier are not criteria I ever use in sourcing fittings. With a long background in motorsport I have seen many $$$ failures due to penny part failures.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app

[freyr]

Orb (o ring boss) fittings are what is pictured in Maine Sail's link, and #8 uses 3/4-16 threads. Very common in industry. Do not put any kind of sealant on them.
Good luck!

[Finistere]

Try WM, my local WM has all the various fittings for Racor. They are not on display just ask at the parts counter.


Sent from my iPad using Cruisers Sailing Forum