james croft
Contributor
I need a SPG high pressure spool for a particular application that calls for one with 4 O-rings on it. All my LDS carry the ones with only 2 O-rings. Does anybody know of a source where I can obtain one ? Thanks !
SPG high pressure spool
- Thread starter james croft
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I've never seen one with 4 o-rings on it. What does it fit? You should be able to get one from the manufacturer of the equipment. If the manufacturer is no longer in business (a distinct possibility) you may not be able to get a new one. If is is worth enough to you, you may be able to get one custom made by a local machine shop.
OP
james croft
Contributor
Several manufacturers use them and I have taken them from US Divers as well as Dacor SPG's. It would not be worth having them machined as I am sure someone has a bunch of them on a workbench somewhere. Any moment a SB member will say "I have 'em".
They differ a bit from the ones you normally see as it has a flange at right angles to the tube located in the middle. Sort of a washer affair but it is all one piece. They have two 03 washers at each end.
They differ a bit from the ones you normally see as it has a flange at right angles to the tube located in the middle. Sort of a washer affair but it is all one piece. They have two 03 washers at each end.
I've seen the flanged spools before, but not with 4 o-rings.
I'm not sure I see the point either if two o-rings (1 on each end) do the job.
I'm not sure I see the point either if two o-rings (1 on each end) do the job.
OP
james croft
Contributor
The ones with 2 O-rings on each end are great for making leaky guages work again. Some guages that have been used and not taken care of develop a leak as the grit and salt crystals wear out the surface that the O-ring seats on. Replacing the O-ring and cleaning the area does not fix the leak. Usually replacing the spool with one of the double O-ring at each end puts the damaged area between the 2 O-rings on the flanged spool and the O-rings rest on undamaged areas. I have a nice compact brass and glass vintage guage that needs this TLC to make it good again.
Along the same lines I have seen both straight and flanged spools with slight variations in lenght - it accomplishes the same thing (having in the o-ring bear in a non worn or corroded spot) but with one o-ring on each end.
R
redacted
Guest
I'm a little skeptical about doubled-up o-rings. If the wet side o-ring fails, it just creates a pocket where SW tends to accumulate and cause corrosion. Once it fails, even a long soaking may not clean it out. With the Scubapro S-wing poppet, the plastic surfaces are not prone to such damage. But with the Mk20/25 piston, I like to open it up and inspect it often to make sure a problem is not developing.
You might just want to try a different length spool. I just went thru my spares and found my flanged spools have 13mm spacing on the o-rings (center to center) and straight spools have either 12mm on the short ones or 14mm on the long ones. A different length spool might engage a seating surface that has not been compromised.
You might even try polishing the seating surface in the SPG a bit. I've had some luck with a damaged seating surface on a Mk5 ambient chamber touching it up with a little Brasso on the end of my finger. If all else fails, try a little brasso on the oring and work it around a bit to remove the rough edges. And then use a 70 duro o-ring which should seal better than a 90 duro.
You might just want to try a different length spool. I just went thru my spares and found my flanged spools have 13mm spacing on the o-rings (center to center) and straight spools have either 12mm on the short ones or 14mm on the long ones. A different length spool might engage a seating surface that has not been compromised.
You might even try polishing the seating surface in the SPG a bit. I've had some luck with a damaged seating surface on a Mk5 ambient chamber touching it up with a little Brasso on the end of my finger. If all else fails, try a little brasso on the oring and work it around a bit to remove the rough edges. And then use a 70 duro o-ring which should seal better than a 90 duro.
OP
james croft
Contributor
Sounds like a different length may accomplish the same thing. Thanks guys.
Based on the shared insights I am trying to decide if this is a useful "service part" or a band aid. 
R
redacted
Guest
Based on the shared insights I am trying to decide if this is a useful "service part" or a band aid.
If it works, it probably doesn't matter and it is a cheap repair rather than an expensive replacement. If it doesn't work, then it will have been an inexpensive failure.
But that's just me - I like fixing things.
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