Cleaning Sherwood First Stage Laser Drilled Flow Control

[tmassey]

Hello!

I just bought several SRB5300. Of course, every one of them has problems with the dry air bleed. The reason why I bought them was because this model has the laser-drilled flow control unit, which according to the manual can be cleaned!

So, I take them all apart. Sure enough, they all have a small screw-in insert in the body of the first stage, and from the top you can see a *really* tiny hole. Unscrew the element and you see the small white filter on the bottom. Use a pick to pry that out and all you've got is the flow control element. Solid metal (nothing sintered) with what should be the world's smallest hole in it. If I *very* *gently* use a brass pick, I can feel the hole. Good so far.

But cleaning it... has not gone well. I've tried ultrasonic cleaning for 10 minutes in 50/50 vinegar and hot water, then soaking in water with a little Dawn detergent (but a higher proportion than I'd use for washing dishes) for about 12 hours, then a thorough rinse and another 10 minutes ultrasonic in clean water. No shininess on the final rinsewater. They are quite clean and shiny!

I stick the flow element alone (I don't have any replacement filters yet) back into the body and toss them on a tank in a tank of water.

No air bleed.

It's very reminiscent of this old thread about the sintered-metal flow control in the piston ( Sherwood dry bleed contaminated piston ). The difference here is that Sherwood always said the piston and its sintered metal was not able to be cleaned -- but they state that the laser-drilled ones *can* be cleaned.

So does anyone know the magic incantation to perform this black art?

 

[fmerkel]

What's the metal? If it's not chromed or subject to acid damage I'd use hot straight vinegar and let the US do it's thing for a good while.

I had one of the early sintered pistons contaminated. I started conservatively, then kept escalating to some nasty stuff. Nothing hurt the piston, but nothing cleaned the bleed either.

 

[tmassey]

Seems like chromed metal. This link has a photo: Sherwood Flow Restrictor Screw #5105-13

Usually 10 minutes with hot half-vinegar-half-water and ultrasound will clean even visibly corroded items, and a second go-around usually takes care of even the worst items. I can certainly try more on these, but the items already seem visibly very clean. They sure are nice and shiny. The only real issue is that I have the cheapest Harbor Freight ultrasonic cleaner, which only runs for 3 minutes. I have to keep pushing the button, and that gets tedious...

 

[BRT]

Sherwood Flow Restrictor Screw #5105-13

 

[tmassey]

Does that link tell you how to clean them? I don’t seem to see it.

 

[BRT]

Does that link tell you how to clean them? I don’t seem to see it.

It tells you how to buy it. You can't clean it for $17

 

[tmassey]

Yeah, but I have *6* of them right now, let alone in the future. I'm assuming I *can* clean it for under $100, seeing as I already own an ultrasonic cleaner... and Sherwood says that they're cleanable!

 

[JamesBon92007]

H
It's very reminiscent of this old thread about the sintered-metal flow control in the piston ( Sherwood dry bleed contaminated piston ). The difference here is that Sherwood always said the piston and its sintered metal was not able to be cleaned -- but they state that the laser-drilled ones *can* be cleaned.
So does anyone know the magic incantation to perform this black art?

According to a Technical Service Bulletin issued in October, 1988 an attempt can be made to clean them. It seems to pertain to pistons that were over-lubricated with silicone grease. Here's what it says"

"An attempt can be made to clean the grease from the flow element. Use a very warm, and fresh batch of cleaning solution in an ultra sonic cleaner. Keep the piston in the bath for a fair length of time. Remove the piston from the fluid, and blow it dry thoroughly with clean dry compressed air. Pay particular attention to drying both sides of the flow control element. Install the piston into the regulator using techniques described in the appropriate Sherwood Service Manual, and check the flow rate as per instruction in the manual. If the flow rate is not quite up to minimum level, then a repeated attempt at cleaning should be made."

One twist I added to this procedure was to dry it with a vacuum (from both directions) instead of blowing it with air. I managed to get my flow rate to just a tiny bit under the specs. Sherwood also says somewhere that if it's clogged it's still safe to use but might be harder to breathe at depth. I didn't notice any difference at depth so I guess I got close enough. As for the laser-drilled flow control it sounds like you already have the instructions.

 

[tmassey]

According to a Technical Service Bulletin issued in October, 1988 an attempt can be made to clean them."

Thank you very much for the information! However, that is for cleaning the *piston* with the sintered-metal insert. Those are pretty much acknowledged as being completely uncleanable.

I'm asking about the laser-drilled insert that goes into the body. This was a mid-1990's improvement in the design with a late-1990's improvement to the laser-drilled insert. Here's a quote from the SRB5300 Assembly and Maintenance Guide:

There are two styles of flow control assemblies. The old style with a
sintered stainless steel flow restrictor and the new style flow restrictor that is laser drilled P/N
5105-13 with a white filter P/N 5105-14. The new style complete assembly part number is
5105-15. If the regulator has the old style flow restrictor and it is functioning (13 to 27 cc/min) it
can be reused, however if it needs to be replaced use the new style. The black gasket can be
reused. The new style restrictor can be cleaned if it becomes plugged. Remove the white filter
and discard it. The white filter must be replaced P/N 5105-14. The laser drilled flow restrictor
can be cleaned in an ultrasonic cleaner and reused.

The problem is, I tried cleaning the insert in an ultrasonic cleaner, and of 6 of them, zero improved. So I must be missing something. Hence my question.

I know I can replace them. But I'd rather learn how to clean them -- I have a *lot* of Sherwood regulators...

 

[BRT]

Thank you very much for the information! However, that is for cleaning the *piston* with the sintered-metal insert. Those are pretty much acknowledged as being completely uncleanable.

I'm asking about the laser-drilled insert that goes into the body. This was a mid-1990's improvement in the design with a late-1990's improvement to the laser-drilled insert. Here's a quote from the SRB5300 Assembly and Maintenance Guide:



The problem is, I tried cleaning the insert in an ultrasonic cleaner, and of 6 of them, zero improved. So I must be missing something. Hence my question.

I know I can replace them. But I'd rather learn how to clean them -- I have a *lot* of Sherwood regulators...

So do I, at least as many as you. I buy the new ones when I need them which isn't often.