Sherwood replaceable bleed orifice ?

[scorman]

Has anyone taken an old Magnum with the permanent scintered filter mounted in the piston and on the opposite side drilled/tapped the piston for a replaceable unit as a permanent solution? Or is that replaceable unit in the body not in the piston?
Then in even later models they claim a replaceable "foam" filter ...really? foam? I am confused
Stew

 

[ams511]

Stew, I am not a Sherwood expert but from what I could piece together is Sherwood has three version of the filters. The first was mounted in the piston and required a piston change if clogged. I know of no one that tried to drill it our and replace it. I would have no idea on what to replace it with. Supposedly these pistons are no longer made by Sherwood. The second version was a replaceable sinter filter placed in the body of the regulator. People say the part is expensive for what it is. I never bought one. The last version uses a foam filter.

My understanding is the filters are not exchangeable between different first stages. There was a thread a while back about people trying to clean the piston filter but I don't know if they were successful or not.

 

[scorman]

Thanks for your reply.
I was drawing a similar perspective, but I still don't see how a "foam" anything can replace the mechanism for a dry bleed.
I have used an ultrasonic cleaner with vinegar with some positive results, but since I am clogged again, I will go for higher octane vinegar (straight acetic acid conc) since it won't attack either the aluminum or scintered element ...trick is how to test w/o submerging the first stage while under tank pressure?
I am tearing part the regs in a day or two and will report back if I come up with any enlightenment.
I have an extra "dead" piston to experiment on.

Stew

---------- Post added May 16th, 2015 at 10:48 AM ----------

update...
I checked out both first stages and they were dry as a bone, the rubber check valves were dry and the seat was clean (may have lubed the rubber?).
As I can best recall, there may have been a bubble or two emanating during dives, but no obvious stream of bubbles as designed. In previous teardowns, yes, there was water above the piston, so I will conclude that the previous ultrasonic cleaning had worked to some degree. I had used straight vinegar and left in US bath for many hours, at which time the liquid gets quite hot. I will do a complete rebuild sometime in the future as I do not have a sense of urgency at this time.

Stew

 

[ams511]

Stew, I apologize if I am telling you something you already know. Vinegar is used primarily to remove corrosion, which may not be the problem. The Sherwood service manual recommends that the first stage internals not be ultrasonically cleaned because of oil (lube and body oils) plugging up the filter. If oil is the problem you are better off using a degreaser like Crystal Green, Dawn, or 409. Just make sure you cycle it a few times in rinse water to get rid of the residue. It is also important that you do not re-contaminate the filter when removing it from the ultrasonic cleaner. The Harlow book recommends laying a heavy-duty lint free paper towel over the top of the tank to soak up any oil that rose to the surface.

Many of us suspect that these filters can be cleaned but dive shops don't want to fool with it. It was quicker and easier just to sell someone a new piston. However with those parts drying up maybe more people will try cleaning the filter.