CPS 1200 Issue

[Andrew]

Don't jinx it :p

I think I did!
If the force needed to push it back is noticeably smaller, then the elastic bands may well be enough.

[SEAL]

Wow this is 5 pages long now...

After staring at it for roughly an hour, I'm beginning to think that the spring might be getting caught when I pull the pin back. Oddly, it works fine when it's open, but when I hold it closed and try it, it gets stuck. It appears to be totally fine otherwise.

[SEAL]

I may have located the problem. Since it's almost impossible to explain in words, I'll give you a thousand words:


Shown is a rough drawing of the valve. The white part is the plunger thing with the O-ring on it. When you push the plunger down, before the firing pin starts to move, the plunger slides over the greenish part that I marked with an "X". After none of the X-marked green piece is visible, the pin starts to move down. What I think is happening is, when you pull the pin back, everything gets pulled back (The X-marked piece is normally inside the plunger thing.), and when you release it, everything springs back except the green thing, which only gets pushed back when you manually push the pin forward. As far as I know, the only thing it would be doing is not holding the plunger in place, so water can leak out.

If you understood that, please let me know what I can do about it.

[atvan]

I think you made it more confusing. It was like -1000 words. Cameras are really neat. You should try one. In the mean time, if things dont move that should, lube, or more tension, and if things move that shouldn't, duct tape(really epoxy, but that isn't how the saying goes).

[Andrew]

I can't quite see how pushing the pin forward would make the green 'X' piece slide out, when it is this that the pin appears to be connected to (surely it would push it further into the plunger?). I think I do see what you're getting at (hope you don't mind me using the image! I would have asked first, but was worried I might lose the image of it in my mind!).



If that is how it works, that seems overly complicated for a trigger valve! Lubrication between piece 'X' and the plunger should help, otherwise something's not quite right inside the plunger, and may need opening also.

Sorry if I misunderstood and this is not what you described!

[SEAL]

It's sort of the opposite actually. It doesn't make a lot of sense to me; I'd make a moving picture like yours, but I don't have any programs that I could do it with.

I got some stuff called "PVC Glue", as it was the closest thing to plumber's epoxy I could find. I hope it works; does anyone know what type of plastic the valve is made out of?

[Andrew]

I just used MS paint and Picasion at 200(ish) pixels! it's pretty good, but you can only use 10 images to make the .gif image. As for valve material, I'd have thought it would be PVC but I'm not quite sure. I'd find that information quite useful aswell!

[atvan]

Likely not PVC. PVC is not usually used for potable water, no reason to have a potential lawsuit over, plus the consitency is wrong. Maybe ABS.

[SEAL]

Here's a drawing of what the valve is doing. Hopefully you'll be able to understand it now.

At position 1, the valve is closed, pos. 2 is when the blaster is firing, and 3 is after you let go of the trigger. I don't know why it's causing it to malfunction though, but maybe rubber bands will fix it.

[atvan]

I get it. So when the x piece gets stuck, there is too much force from the spring to open the valve?

[Andrew]

Something must be causing enough friction to stop the spring from pushing the X piece back into the plunger. This could be between the plunger wall and the piece X, or more likely somewhere else in the trigger system (if it was between the plunger wall and piece X then it shouldn't affect the seal as much as you earlier described). If I understand correctly, when the X piece jams, not enough force is being applied to the plunger itself, and so doesn't seal properly.

Is there a spring inside the plunger between it and piece X? If so that would explain why it doesn't seal properly when piece is is not inside the plunger. When piece X is inside the plunger it would compress the spring, and apply more force to the plunger against the seal, to make the seal tighter.

[SEAL]

If I understand correctly, when the X piece jams, not enough force is being applied to the plunger itself, and so doesn't seal properly.

EXACTLY. I'm not sure what to do about it, but I think I can fix it with rubber bands. Of course, I have to close the valve up first. I applied some of the PVC Pipe Weld to the PRV, just to see whether or not it would stick to the type of plastic used for the internal plumbing in this blaster. It appears to stick, so I think I'll use it to try and seal up the valve whenever I get a chance.

[Andrew]

So it's more like this:


That does sound like friction somewhere else in the trigger system, most likely at a point where the firing pin or piece x touches any part of the outer casing. This also makes sense because you did mention lubrication helped it a bit.

Try lubricating (again) wherever moving parts meet (not around the seal obviously) including between the plunger and piece X, see if you can find what is stopping the X piece moving forward (could be almost any of the places where parts move past each other) and try the elastic bands. If the elastic bands work, then you might consider a more permanent spring upgrade inside the valve. Springs do wear out over time, and apply less reaction force when compressed. You said it was a bit rusty. it may not be much, but it might still be enough!

[SEAL]

I lubed it, so I guess I'll wait until tomorrow before sealing it up. I'm kind of nervous about doing it though...

[Andrew]

Don't jinx it :p

I think I did!
If the force needed to push it back is noticeably smaller, then the elastic bands may well be enough.

I'm not saying anything this time!

[SEAL]

Well this sucks... I applied the epoxy stuff, and since you need to heat it to 190 degrees F for it to set, I took out the heat gun and went over it for about 10-15 minutes; unfortunately, while it apparently wasn't hot enough to set the epoxy, it was hot enough to start melting the plastic, and the valve got deformed. So I am unsure of what to do at the moment. Obviously, the stuff I brought doesn't work too well, and I would need something else. The problem is that I'd need a LOT of epoxy or whatever to fill in the gaps, since the valve is bent out of shape.

Advice? I suppose I could heat it again and try to bend it back, but the risk is probably too great to make it worth it.

[Andrew]

190°F? Bloody hell!!!!

How badly is it deformed and where (pic if possible)? If it's not by much, heating it a bit (steam from a boiling kettle usually does the trick) should relieve the stress allowing it to move back into it's original shape with only a little persuasion. If it's deformed a long way (again pics would help us decide) and you are unable to fill the gaps, then there isn't much you can do I'm afraid!

Some epoxies can be used to fill gaps and still hold pressure, again depending on gap size. If the seal faces are still in shape, then you should be fine as long as you keep the two halves of the valve clamped tightly together whilst they set. Would it be possible to use bolts instead of epoxy? It would mean drilling through the casing but, again, as long as the seal faces are not deformed, and the holes are on the outside of the seal (not inside where the pressurised water is) it should still work. This is, essentially, how a car engine is held together (two metal faces with a gasket in between acting as a seal held together with long bolts)!

You might be able to find someone with a CPS valve from a broken blaster to replace it (or just the deformed bit), or replace it with a ball valve (WW style) or homemade pull valve.

[atvan]

Most epoxies generate their own heat. What is this stuff?

[SEAL]

It's called "PVC Pipe Weld", and it's a "single component heat-activated epoxy".

Here's a picture of it.


Here's a shot of the deformed area. The other side appears to be fine.


And this is what it looks like with the nozzle half on it.


I also noticed another very disturbing problem; the yellow lever that's in charge of pulling the pin back is now rubbing against the pipe right above it (The one that connects to the PC.).

[Andrew]

That does look quite badly deformed! The kettle trick might not be enough for that but may be worth a try. The alignment looks off aswell, but it might still work as long as the seal does still align with (and make full contact with) the inside face of the valve. Unfortunately it may well be irrepairable!

I know atvan was probably right about it being ABS, but 190°F seems pretty high even for PVC! I suppose for standard pipe deformations aren't as critical.