Oring popping out

[TheOldHokie]

I am suspecting they may not be MORB fittings. -6 MORB major thread diameter is .562 and 3/8 BSPP is .656
-8 MORB is 3/4x16 so no way an ORB fitting will work in a BSPP port

We know the P and T ports on the Vevor valve are female G1/2 which is a .825 x 14 Whitworth thread.

A male SAE-08 is .750 x 16 UNF thread which will screw in but will not be mechanically solid or pressure tight.

He needs BSPP port fittings. Which begs the question of what is currently in the G3/8 cylinder ports.

Dan

 

[ruger1980]

We know the P and T ports on the Vevor valve are female G1/2 which is a .825 x 14 Whitworth thread.

A male SAE-08 is .750 x 16 UNF thread which will screw in but will not be mechanically solid or pressure tight.

He needs BSPP port fittings. Which begs the question of what is currently in the G3/8 cylinder ports.

Dan

G1/2 or BSPP is 14TPI. The minor diameter of G1/2 is 0.7335 while the major of 3/4x16 is 0.7486, so an overlap of app. 0.015. Yes the fitting would probably slide in but would never tighten or seal.

The OP stated this did not leak for a period of time before its started so the connection must have been somewhat secure for a period of time.
Looking at his pic of the fitting it appears to have a bevel instead of a square shoulder below the o-ring. ORB always have a square shoulder with no bevel where the o-ring seats. G or BSPP quite often have a bevel which centers the sealing washer.

Sorry I see you edited your post to correct the thread pitch

 

[TheOldHokie]

G1/2 or BSPP is 14TPI. The minor diameter of G1/2 is 0.7335 while the major of 3/4x16 is 0.7486, so an overlap of app. 0.015. Yes the fitting would probably slide in but would never tighten or seal.

The OP stated this did not leak for a period of time before its started so the connection must have been somewhat secure for a period of time.
Looking at his pic of the fitting it appears to have a bevel instead of a square shoulder below the o-ring. ORB always have a square shoulder with no bevel where the o-ring seats. G or BSPP quite often have a bevel which centers the sealing washer.

View attachment 135978

Sorry I see you edited your post to correct the thread pitch

VEVOR says the ports are G1/2. There is no reason to think otherwise. The PO says he purchased ORB fittings. That seems to be pretty definitive.

Here is a P40 valve with G1/2 inlet port - .825 X 14 Whitworth.

The fitting in my picture is SAE-8 - .750 X 16 which is what the PO thinks he has.

The SAE fittimg screws in and tightens compressing the oring but is clearly well undersize and lacks full thread engagement. Put 1000× PSI on the inlet and my guess is it pushes the male fitting out of the female threads. I suspect its the fitting that is pushing out exposing the oring and the threads may have been damaged in the process.

I am confident a couple 1/2" BSPP port adapters will fix his leaking problem.. Still wondering about the fittings in the work ports...

 

[awesome]

VEVOR says the ports are G1/2. There is no reason to think otherwise. The PO says he purchased ORB fittings. That seems to be pretty definitive.

Here is a P40 valve with G1/2 inlet port - .825 X 14 Whitworth.

The fitting in my picture is SAE-8 - .750 X 16 which is what the PO thinks he has.

The SAE fittimg screws in and tightens compressing the oring but is clearly well undersize and lacks full thread engagement. Put 1000× PSI on the inlet and my guess is it pushes the male fitting out of the female threads. I suspect its the fitting that is pushing out exposing the oring and the threads may have been damaged in the process.

I am confident a couple 1/2" BSPP port adapters will fix his leaking problem.. Still wondering about the fittings in the work ports...

Correct, what I have now is 3/8 NPT female by SAE-8 male.

The inlet ports 1/2 bspp as per the information you gave me when looking for a PB sleeve in another thread.

Not sure why you need the size of the cylinder ports but here it goes: 1/2 bspp also. The plug on one of the cyl port fits on the P port, so 1/2 bspp

This is what is connected on A/B. Notice that ring. Is that BSPP? Does it always come with that ring?

 

[TheOldHokie]

Correct, what I have now is 3/8 NPT female by SAE-8 male.

The inlet ports 1/2 bspp as per the information you gave me when looking for a PB sleeve in another thread.

Not sure why you need the size of the cylinder ports but here it goes: 1/2 bspp also. The plug on one of the cyl port fits on the P port, so 1/2 bspp View attachment 135979
This is what is connected on A/B. Notice that ring. Is that BSPP? Does it always come with that ring?

OK - thats informative. The BSPP adapters do not always come with tje sealing washer and some wont work with them. The DHH link I provided includes the washers. Buy two of those adapters and the JIC elbows for your hoses and you should be good to go.

Dan