Sherwood dry bleed contaminated piston

[BRT]

Thank you for jumping in Rob. If you look at the first post it describes my predicament > saltwater intrusion into the ambient chamber, probably been sitting that way a long time. Threw the piston into the US bath with everything else. Bleed not working. I've tried a whole lot of different things to 'clean' it. Nothing works, at least so far.

What if I drilled a tiny hole through the plug? I have some very small drill bits, though I'm not at all sure how I would chuck them. Too much flow?

If that's an absurd notion the piston is from an Oasis, around 1995. Can't find any real ID marks. The piston has the deep groove for the spring on the underside of the piston head. Earlier (other?) models seem to be flatter on the underside.

You can't drill a hole that small.

 

[axxel57]

I once wanted to see how this filter looks like, so I hit it out of the piston.

It's a sintered massive, but relatively soft piece of metal and I would not know where to get it, but I'm sure that there are applications which use that type of filter material for whatever.

In the US it might be worth to investigate......

 

[fmerkel]

I was afraid of that.....

 

[redacted]

What is the problem with plugging up that filter with something like JB weld and drilling holes into the ambient chamber?

 

[axxel57]

Is no problem, there is already one hole for the one way bleed valve, but the main spring chamber is not made for salt water, the chrome coating is very thin and will be destroyed soon, so you will have very fast a lot of 'corrosion' and dirt clinging to the inner of the chamber....

Apart from that I would not like too much altering the original design for a practicable, but pretty far away from the original design approach........

You find these 1sts for cheap money in the bay, just have to check and make sure that the filter works.

 

[fmerkel]

On the balanced 1st stages the IP pressure chamber screws down over the ambient chamber. You need to be able to adjust (screw) that top portion up and down to set the IP. So holes you drill might not align next time you overhauled and tune the reg. The piston stem is very short so there is not a lot of space in the ambient chamber.
Possible, yes.
Practical, not very.

 

[axxel57]

Sorry, but I think you don't really understand the concept of adapting to depth in a 1st stage.........

 

[fmerkel]

Sorry, but I think you don't really understand the concept of adapting to depth in a 1st stage.........

The discussion has gotten a bit off course, which can be fun sometimes. But I don't see where your comment is helpful for de-contaminating the piston plug. I'm certainly not going to be drilling holes in the first stage to deal with the problem.

It seems there is no really reliable way, possibly not any way of doing that, which makes me think this is a critical weakness in the design, which has been change in their more modern regs.

 

[BRT]

The discussion has gotten a bit off course, which can be fun sometimes. But I don't see where your comment is helpful for de-contaminating the piston plug. I'm certainly not going to be drilling holes in the first stage to deal with the problem.

It seems there is no really reliable way, possibly not any way of doing that, which makes me think this is a critical weakness in the design, which has been change in their more modern regs.

Not too much of a weakness. If it gets clogged the reg still works and the lack of bubbles tells you that you need a new part. Lots better than some failures.

 

[axxel57]

I always considered that design as questionable for the reason you mentioned, and I don't understand why Sherwood just stopped supporting their customers with at least new pistons for these models.

The newer models are using a laser drilled 'Flow Restrictor Screw', which is clogging at least as fast as the old sintered filter in the piston, but can be purchased separately until today.

And the latest models ( like the SRB9110) finally gave up the constant bleeding system and use a Schrader Valve system to compensate for depth, keeping the 1st stage dry.

Yesterday I was checking and found an old SRB3202 with a Magnum from the Eighties

When I opened it it was like brand new from the inside with the newer piston model. I didn't measure the bubbles, but I'm sure that the filter is completely okay.

I serviced it, now it looks like new and I can do a fast deep dive to try how fast the air in the main spring chamber is following up the demand during the descend and if I can feel something.

I have lots of Sherwood regulator part (mostly newer models with the flow restrictor screw), but I might have also still another piston with filter laying around. If one seems to be okay, I come back to you.

Good luck.....