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Discussion of diving methods and equipment available prior to the development of BCDs beyond the horse collar. This forum is dedicated to the pre-1970 diving.
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SurfLung
Master Diver
Posts: 1597
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Snark III Navy

Thu Dec 20, 2018 10:54 am

Snark III Navy...
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- Since the United States Navy Seals use Snark III regulators for training, I decided to give this Snark III Silver I've been working on a "USN" mouthpiece. I bought a nice green curved one and gray hoses from Rob's Scuba Museaum. (Apologies for the photo quality, I finished it late last night.)
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- This is the St. Vincent's regulator I've shown here previously. I was going to test dive it at the public pool but when I checked the IP with my home made IP gauge, the needle appeared to move really fast to high pressure and looked like it wasn't stopping until I turned off the air. I took it to the pool for submersion to see if the over pressure valve was leaking... And it wasn't. So, I set the reg aside for further thought, consideration, and repair.
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- My first thought was that the high pressure seat was leaking. But if that was the case, the OPV should have been releasing bubbles. So then I thought "Maybe the IP is just set too high". I have two other working Snark regulators so I checked their IP to see what is normal. They were both dead-on set to 150 psi when mounted to a 300 psi tank. But when I checked this Snark III Navy, the IP was set to nearly 200 psi (175 actually) and the gauge only goes up to 200 so that's why it looked like it was going off the chart when I turned on the air.
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- Long story short, I adjusted the IP to 150 like the other two Snark IIIs and it held dead-on steady and returned to that setting through several tank turn-ons and lever pushes. So, the HP seat isn't leaking and I think I'll leave well enough alone there. And the OPV isn't leaking either... But I noticed the OPV was adjusted right down to the highest pressure stop point... Worth noting. But everything is working and looking great so I closed up the patient and installed the new hoses and mouthpiece.
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- Now this morning I found my PDF copy of the Snark III Silver service manual and was able to look up some proper settings: The IP is supposed to be 125 psi when attached to a 500 psi tank. Furthermore, the OPV is supposed to release when IP goes over 150 psi. So, I've got a littleways to go before I have this Snark III Navy all set up perfectly... Same with my other Snark IIIs. But at this point they are all breathing easily, consistently, and smoothly.
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Snark III Silver vs Older Snark IIIs
- My older Snark IIIs are very similar to DA Aqua Master regulators in the 1st stage. The nozzle unscrews to reveal an almost identical 1st stage system. On this new Snark III Silver, my attempt to remove the nozzle gave me nothing more than a nut and yoke... The nozzle is integral with the regulator body. The diagram in my Snark III Silver service manual does not show this arrangement... It still shows the removable nozzle.
- And, the Snark III Silver has an HP port for a pressure gauge where the older regs do not.
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How to Adjust the OPV and IP...
- I've been thinking on this and its explained in the service manual. First you adjust the Interstage Pressure (IP) to 150 psi. Then you adjust the the Over Pressure Valve (OPV) to release at the 150 psi IP setting. Finally, you re-adjust the IP back to 125 psi when mounted to a 500 psi tank. Stay tuned!
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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SurfLung
Master Diver
Posts: 1597
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Re: Snark III Navy

Sun Dec 23, 2018 1:32 pm

All Done!
IP is 125 psi and OPV is 150 psi
- It is SO Satisfying to service one of these Snark III regulators by-the-book instead of guessing at what should work or just trying not to change any settings when disassembling and reassambling. I made up that DIY IP gauge awhile back but had not really put it to use. Wow. It has made all of the difference here. No guesswork when you have the parts, tools, and instruction manual!
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1. The OPV is not going to leak unless I develop a leak in the HP seat... It's not set too borderline same pressure as the IP.
2. The IP is set properly to 125 psi when the tank source is 500 psi. This regulator now breathes easily and reliably... It did so before I serviced it but now I know just putting it back together the same doesn't guarantee the settings will be right. So, I'm lookingf forward to setting up my other two Snark IIIs with proper IP and OPV psi levels.
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SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

Vancetp
Master Diver
Posts: 305
Joined: Tue Oct 04, 2016 7:26 pm
First Name: Phillip
Location: Belmont CA

Re: Snark III Navy

Sun Dec 23, 2018 2:15 pm

Sweeeet. Nice work on that Silver, Eben.

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SurfLung
Master Diver
Posts: 1597
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Re: Snark III Navy

Wed Dec 26, 2018 3:27 pm

Vancetp wrote:
Sun Dec 23, 2018 2:15 pm
Sweeeet. Nice work on that Silver, Eben.
Thanks Vance!

Snark III "SILVER" is More Different Than I Thought
- I found another service manual for the Snark III SILVER and it gives completely different values for the IP pressure and the OPV pressure... WAY higher values. Here's the link for the Snark III SILVER manual: http://www.altes.tauchen.seveke.de/tech ... ir-eng.pdf
- I can tell that this set of instructions is for the SILVER because the drawing shows the 1st stage nozzle integral to the regulator body.
- It says the Over Pressure Valve (OPV) should be set to 210 psi and the Intermediate pressure should be as high as 170 psi when the tank is at 500 psi. It gives a range from IP 175 at 300 psi tank pressure to IP 120 at 3000 tank pressure.
- This is all fine except my OPV can't go any tighter than 150 psi. So that's where I've got to start... either get a new spring or a shim to increase the OPV adjustment range and allow me to set it to release no lower than 210 psi.
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

User avatar
SurfLung
Master Diver
Posts: 1597
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Re: Snark III Navy

Wed Dec 26, 2018 4:33 pm

TWO Types of Snark III Silver?
- I have noticed there are printed service manuals for Snark III "Silver" in which two different versions of the regulator are shown and two different sets of pressure settings for Intermediate Pressure (IP) and Over Pressure Valve (OPV).
- The first type has a removable 1st stage nozzle.
- The second type has an integral 1st stage nozzle.
- VDH has diagrams of both types but the only service info available is connected to the diagram of the removable 1st stage nozzle.
- The service info that's connected with a diagram of the integral 1st stage is from the other (european?) website.
http://www.altes.tauchen.seveke.de/tech ... ir-eng.pdf
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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