Solenoid stuck open! No Problem With This

dave t

Agreed but carrying back up o2 takes the uncertainty out, its much easier to fly the unit manually on the button than opening and closing the tank valve.

A reliable way of isolating the solenoid would be good but sliders are not the way to do it.

Dave

Gilles

I guess we can't find anything to argue about.

Who would want that anyway.

__________________
Gilles
http://www.dirrebreather.com

Dave Sutton

Dave T is right. Sliders are no good for this. A simple chrome plated brass ball valve in the same sort of system works perfectly. From a tactile standpoint you can feel (and change) the position even with thick gloves, and they never change position without intent. I've added them to... oh.... 25 rigs to date? 100% satisfaction and zero defects. Cost is lower than the slider too and the form factor, if sensibly assembled, is better: The ones I build have the inlet and outlet hoses parallel to each other, not in the "loop" as shown in the proffered part discussed initially.


Dave

.

luxrok

Dave, any chance you can share a photo of your installation of the ball valve?

__________________
Quiet Diver: A Cave Diving Blog

Close Circuit Rebreather Apparel

The whole business of authority is to interfere in other people's business.

Dave Sutton

Uhh.... sure. Might be Weds before I can shoot photos, I'll be flying until then.


Basically, the ball valve (green handle!) screws into a small brass block that has (2) ports threaded into one face. The "goesinta" hose is threaded into the block, the gas makes a 180 degree turn in the block, goes thru the valve, and the "Goesouta" hose goes to the solenoid. The two hoses are paralleled about 1 inch apart. There is a third port at a 90 degree orientation on the block that is usually threaded, but to/from which 02 can be taken/added. Some people use it for a deco open circuit 02 regulator. The extra port is contiguous to the original 02 first stage port, so if you FEED gas to that point and TURN OFF the internal cylinder valve, you are feeding both the solenoid AND the manual add with offboard gas. I generally place a QC-6 there and it's the "does it all 02 place" for the rig. If you are really paranoid about the QC-6 leaking, a second ball valve can be added there too. The entire thing is still tiny.

Two birds with one stone: Solenoid Isolation AND offboard 02 available to both solenoid and manual add valve. Life is good. Plus, when offboard 02 is used, the solenoid STILL can be isolated!

I make a very similar thing for offboard diluent, BTW. The valve isolates the ADV (great on deco) while still allowing the diluent manual add to be used, and similarly allows offboard diluent to be plugged in and made available to both the ADV and manual add (and still lets the ADV be isolated from offboard dil while allowing the manual add to see it). Another little goodie from The Little Diveshop of Horrors. I ought to advertise...


Dave

.

diverreb

What exactly is that you guys don't like about the M & J shutoffs?

Not that I have a ton of experience with them, but I've never seen one fail, they are stiff enough that they don't accidently slide one way or the other, and if properly rigged can be used with cold water gloves on.

We've been using the Apex shut off's on deco regs for years and while they are easy to slide, I haven't seen a failure of one of those either.

One of the keys is maintaining the equipment. Check & lube the o-rings on an annual or semi annual basis and replace them every two years.... Same as you would a Reg.

As far as forgetting to check if it's open or closed... That's what check lists are for.

Relating to number of acceptable failure points.... It's not one size fits all. If I'm an Exploration, Deep Cave, or Deep Wreck type diver then limiting failure points is probably high up on my list.

If on the other hand I'm a recreational rebreather diver ( in my case 95% of my dives are 160' or less, non cave, non wreck penetration, and not super long bottom times) then I'm willing to accept an additional potential failure point or two in the plumbing, if it makes sense for cleaner routing, or serves another function, like the O2 shut-off.

The logic here is that if you properly maintain all you gear the probability of an actual catastrophic failure from any of these additions is slim. In the event that slim chance happens, you should be carrying enough bailout that worst case is you blow a dive and bail out.

Just my opinion...

Richie

Dave Sutton

You can't touch them and know what position they are in with gloves on.
You can't see visually easially what position they are in.

In some applications this is OK (second stage isolation). On deco regs, they work dandy.

In other applications this is not optimal, and a ball valve of nearly the same size is a better choice.
In some other applications a globe valve of similar size is a better choice.

Personally, I do not recommend them for use on manifolds, where small ball valves are a better choice. At times on manifolds I mix ball and globe valves so two valves are impossible to confuse by feel. Examples are the sort of manifold I'll photograph and show later this week. Another is the hang-gas (umbilical 02) manifold we use. We could use the sliders to isolate the (2) 02 regs, or we would use ball valves at the hose/manifold point. We use the ball valves as you can see if they are open or not, and can check them by feel and by eye lots easier. The right tool for the right job will mean a mix of different tools are used.


In this particular application, the form factor drives a 'loop of hose' approach that is neither clean nor elegant. It's an easy 'off the shelf' way, but not IMHO the 'best' way.



Dave

.

diverreb

Dave,

Thanks for your input. Look forward to seeing the photos of your ball valve arrangement.

Richie

Dave Sutton

What I didn't mention is that I don't have any in stock, so will need to make one in order to show one....

So, the obvious question is "who wants it when it's done"?

And I'll need to know the exact lengths of 'goesinta' and 'goesouta' hoses and the fittings required at each end as well as offboard 02 quick disconnect desired (if desired, otherwise the port will be plugged). Hoses are, naturally, color coded green (diluent side would be blue).


Dave

Shaunzxr

I would be interested
I would need 3/8 unf male at one end, valve in the middle and 9/16 unf female swivel at the other

This below, with your ball valve in the middle instead of the sliding flow stop

SCUBA Diving Equipment and gear for Technical, Wreck and Cave Diving: Dive Rite, Inc - Product Catalog - Solenoid Inline Shut-off

Not sure exact hose length will let you Know
Can you PM me with cost. Thanks