User avatar
ScubaLawyer
Master Diver
Posts: 1649
Joined: Thu Apr 08, 2010 11:25 am
First Name: Mark
Location: Laguna Beach, CA

USD reserve washer question

Sat Aug 03, 2019 2:45 pm

Quick question. As you can see from the schematic versus my manifold/valve, I am missing #21 washer. Is it mission critical to have it? Without it am I going to have a higher/lower pressure to indicate the reserve needs to be activated? If critical,  what thickness washer do I repace it with? (It's number 0517-06 in USD manual). As always, thanks for everyone's assistance. Mark

Image
Image
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

User avatar
luis
VDH Moderator
Posts: 1747
Joined: Thu Jun 30, 2005 9:28 pm
First Name: Luis
Location: Maine

Re: USD reserve washer question

Sat Aug 03, 2019 3:24 pm

Any washer / spacer there will increase the spring force and therefore the pressure required for the gas to push past the closing seat. In other words, the amount of the reserve may go up some.
Luis

Buceador con escafandra autónoma clásica.

User avatar
ScubaLawyer
Master Diver
Posts: 1649
Joined: Thu Apr 08, 2010 11:25 am
First Name: Mark
Location: Laguna Beach, CA

Re: USD reserve washer question

Sat Aug 03, 2019 3:37 pm

luis wrote:
Sat Aug 03, 2019 3:24 pm
Any washer / spacer there will increase the spring force and therefore the pressure required for the gas to push past the closing seat. In other words, the amount of the reserve may go up some.
Thanks Luis, that is sort of what I figured but usually the more I try to visualize a concept the more basackwards it becomes in my feeble brain. I may look for a small washer that will fit the bill. M
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

User avatar
SurfLung
Master Diver
Posts: 1763
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Re: USD reserve washer question

Tue Aug 06, 2019 12:51 pm

A Story About That Washer - My favorite Twin 38s have always had a good functioning J-Valve until last winter when the manifold started leaking on the J-Valve side. Well, when I opened it up, I found the seat had 3-4 washers and the spring was busted in the middle. The leak was due to something else and apparently the J-valve worked fine in this broken spring with too many washers condition.

I took a new spring off one of my newer manifolds, put it together with one washer and re-assembled with a new J-valve seat. WOW. That J-Valve now works really great. It must be better than before but I was wondering: Did putting in too many washers make the old spring break? Or, was the old spring weak and the too many washers were used to make the J-valve work better? :?:
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

User avatar
ScubaLawyer
Master Diver
Posts: 1649
Joined: Thu Apr 08, 2010 11:25 am
First Name: Mark
Location: Laguna Beach, CA

Re: USD reserve washer question

Tue Aug 06, 2019 4:51 pm

SurfLung wrote:
Tue Aug 06, 2019 12:51 pm
A Story About That Washer - My favorite Twin 38s have always had a good functioning J-Valve until last winter when the manifold started leaking on the J-Valve side. Well, when I opened it up, I found the seat had 3-4 washers and the spring was busted in the middle. The leak was due to something else and apparently the J-valve worked fine in this broken spring with too many washers condition.

I took a new spring off one of my newer manifolds, put it together with one washer and re-assembled with a new J-valve seat. WOW. That J-Valve now works really great. It must be better than before but I was wondering: Did putting in too many washers make the old spring break? Or, was the old spring weak and the too many washers were used to make the J-valve work better? :?:
So your're saying its a chicken or the egg conundrum? :)

As to the soft washer (#19) I happen to have a NOS replacement but it is my last one. I've heard some folks just use an o-ring in place of that seal. Any clue as to what size o-ring would work? Just stuff i think about. Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

User avatar
captain
Plank Owner
Posts: 1440
Joined: Mon Jul 04, 2005 11:32 am
Location: LaPlace, LA

Re: USD reserve washer question

Sun Aug 11, 2019 11:20 am

More than anything I believe the washer's purpose is to provide a flat seat for the spring to seat against.
Captain

Return to “Tanks and Valves”

Who is online

Users browsing this forum: No registered users and 7 guests