NPT fittings in an AC system?

[mechengdude]

If you folks were to review a design for a vehicle AC system that included a manifold with NPT connections, what would you say? Seems to me that NPT is a bad choice for moving R-134a, won't it bleed out over time.(even with pipe dope)

Correct me if I'm in error.

thanks

 

[newmep]

A/C fittings should be SAE, type and preferrably backed up with an O-ring system. Vibration is severe in this application.

 

[MintJulep]

NPT is the work of the devil.

 

[TXiceman]

Who in the world would use an NPT connection on a R-134a unit?

Since they are already there, you need to clean them well and coat them with A Loctite product specifically for refrigerant service. It will hold pretty well and can be heated to remove the plug later.

Ken

Ken
KE5DFR

 

[mechengdude]

Thanks for your help.

The short answer is someone that has no buisness designing things specified a manifold with NPT connections.

 

[imok2]

NPT threads have been used on refrigeration systems for years For example, all the gauges as in manifold gauges used on refrigeration systems are NPT. In amonia systems a lot of the piping systems are NPT.

 

[mechengdude]

imok2

Thanks for your input. Are the manifolds you are referring to "in-line" (ie) constantly presurrized or are you talking gage manifolds for checking the high and low side as a diagnostic tool?

 

[imok2]

Both!