Checking IP

[nikeajax]

For those of us who are relatively new to refurbishing our own gear, here's a tip for ya... Don When checking the IP on a single hose reg, make sure you have at least one down stream second stage on the reg. If the valve seat is bad, the down stream valve will act as an OPV (over pressure valve): you can't do this with an up stream valved reg. The down stream valve will vent off the the over pressure, instead of killing your IP-gauge An up stream valve will seal up very tightly with no safe way to vent it...

Just because the valve seat looks good, doesn't mean that it is--grumble, grumble, grumble

Jaybird

[diverdon]

Stout advice from one who probably learned the hard way  I need to play with some of these old regs I have laying around and checking the IP is good clean fun! 
Actually I picked up a few older Sherwood Magnum Blizzards lately and two have a slight leak and the third barely puts out any air when the purge button is cranked. Anyone have a pdf of the manuals and maybe a shim or two?

Thanks in advance and thank you Jaybird for making me grab the keyboard   I've been slacking a bit lately,and it has everything to do with the current holiday and my 6 year old daughter. Hey, I'm not complainin, just sayin.

Cheers,

Don

[nikeajax]

Holiday, what holiday, I always dress like this:



Slim, Boson's mate aboard the sloop Pelican

[cnotthoff]

Don,

You probably know this already, but after over 20 years of telling divers that stream of bubbles coming from a Sherwood 1st stage is normal, I can't stop myself.

Blizzard, Brut, and Magnum first stages use a "dry-air-bleed' system to sense ambient pressure. If there isn't a small stream of bubbles coming from under the rubber plug that looks like one of the low-pressure ports, the intermediate pressure will not increase with increasing depth. Theoretically, the regulator would stop breathing if you took it deep enough.

The only fix for no bleed is to replace the piston. Later models of Sherwood regs use a replaceable bleeder element.

Good Dives,

Charlie

[nikeajax]

Oh, hey Charlie, do you have any Mares Abyss second stage diaphragms--I hope? I need a couple for my Voit MR-12 original configuration, not the bull's eye model...

Jaybird

[diverdon]

Oct 31, 2014 10:49:03 GMT -8 cnotthoff said:

Don,

You probably know this already, but after over 20 years of telling divers that stream of bubbles coming from a Sherwood 1st stage is normal, I can't stop myself.

Blizzard, Brut, and Magnum first stages use a "dry-air-bleed' system to sense ambient pressure. If there isn't a small stream of bubbles coming from under the rubber plug that looks like one of the low-pressure ports, the intermediate pressure will not increase with increasing depth. Theoretically, the regulator would stop breathing if you took it deep enough.

The only fix for no bleed is to replace the piston. Later models of Sherwood regs use a replaceable bleeder element.

Good Dives,

Charlie

Hey Charlie, I am familiar with the first stage dry bleed design of these regs as I have had a few in the past. Its not a stream of bubbles type leak that I was talking about. Just a second stage leak after turning on the tank or pressing the purge. I haven't had two of the three in the water yet. But I suspect I'll be needing some parts when I do decide to crack them open. I bet you'd have some parts available...

Thanks,

Don

[SeaRat]

Charlie, this may be the cause of an interesting regulator problem that was discussed on Scubaboard titled "Regs do not always free flow when they fail." You might want to add to that discussion, as the failure occurred at 60 feet.

John

[cnotthoff]

Don,

I figured that might be the case. Like I said, I couldn't stop myself. I'm actually running low on Sherwood parts myself, so can't help there.

John,

I looked at that thread. I closed it quickly, because my doctor wants me to watch my blood pressure. The whole "I am no reg expert, but I have taken apart my reg" crowd makes my systolic spike.

I enjoy looking in on this group, since most members seem to have a good understanding of the mechanics of scuba regulators. Members here also take their safety but not themselves too seriously.

Good Dives,

Charlie

[sitkadiver]

Oct 30, 2014 18:12:32 GMT -8 nikeajax said:

Slim, Boson's mate aboard the sloop Pelican

One of these days Jay, we're going to party together.......


The only thing I would add to your great IP advice is that when you first check the IP on a reg: open the valve very slowly and watch the guage, while keeping it at an angle from your face. I've had some older regs with bad volcano openings and seats run the IP up to tank pressure. NOT GOOD!

[scubadiverbob]

All I've ever had to replace on a Sherwood regulator is the two piston o-rings, the HP seat on the piston, the o-rings on the second stage and the LP seat on the second stage. After overhauling the first stage the IP should be like 130 psi or so. Then, I adjust the LP seat by opening it to where it just starts free flowing and back it off a quarter to a half a turn .... after that never had any problems with any Sherwood regulators I've ever owned (or worked on). Never had to replace any diaphragms in the second stage. Usually when the IP would start rising, replacing the HP seat would solve the problem (and they do go on Sherwoods). A piston being defective could maybe cause it? Don't know if this helps any ... or answers any questions. If you look at photos I've posted of Andrew, he dives a Sherwood regulator, and Dacor BC, all the time .... I keep trying to get him to try a DH .... it's still "it doesn't have a purge button, Dad"

Sherwood SH are probably the easiest single hose regs to service and overhaul (if you have the tool to tale the covers of the second stages off that screw on and off).