Question about the "cash valve" on liquid tanks...Valve covers?

[chrissyo.]

So the last tank i had started venting a lot more than any of the last ones that I've had, and most of the ones I've had were in the summer and they didn't vent as much as the one i just had. I came to find out that the "cash valve" was set to the maximum setting. That tank looked very new and clean, and i was able to find the "cash valve" very easily. I ended up finding it however once the tank was pretty much empty so it didn't really do me any good. But since that tank was so new, the little bolt on the cashvalve that you unscrew the lower the pressure even had little numbers written on it so you can know what your setting it to. The little numbers really reassured me that the bolt i was twisting was the one i wanted to twist, but the tank i got today looks a little different and i wanted to ask a few questions before i just start twisting shit.
When the tank came today the first thing i did was went to find the "cash valve" so that i could set it first thing and see if that would help this tank not vent as much. When i started looking though it seems like this tank has some type of cover put on it.
47535
Has anyone ever seen one of these? It sucks because right when i find out how to adjust the cashvalve i get a tank where i cant do it. The other thing that's a bummer is that the only the holding the cover on is one screw, but the shop owner cut out part of the screw so that it can only be screwed in, and not backed out.
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My other question is if i am even looking at the right valve. I know its one of 2 that i am looking at but not for certain. Pictured below is the whole pressure building unit and I'm not sure if the "cash valve" is the one on the left of the "regular open/close valve" with the cover or the one on the right that is exposed with the little with tip.
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And i know that the cashvalve is set high because i just got the new tank today and its already gone up about 15psi within like an hour and a half after working for quite a bit. Lemme know what you guys think...

[funksizzle]

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[Greymatter Glass]

um.

wut?

I've never heard the economizer valve referred to as a "cash valve" ... but if you know what they're for, it's kinda funny, in an asshole kinda way.

...reading more....

Ok... so I've never personally had a tank with 2 economizer valves, but I see what they're doing. One is on the pressure builder, and it probably set fairly high - that's the one with the cover. I'm not really sure what the point is, but I see what they've done... *shrug* I would ignore that one, and make sure the actual pressure builder valve (the large round knobby knob) is closed tight. The other one is the by-pass or what is actually the economizer, or what you're calling a "cash valve"

[nodice]

The white thing in the third picture should be screwed all the way out(unscrewed), and the knob should be closed. The tank might be building pressure quicker more naturally though, as the weathers getting warmer.

[Greymatter Glass]

The white thing in the third picture should be screwed all the way out(unscrewed), and the knob should be closed. The tank might be building pressure quicker more naturally though, as the weathers getting warmer.

The external temperature of the tank plays a very minimal role in pressure building. Just as when you touch the outer tank it's not -300ºf on the outside, neither does exterior temperature transfer to the inner tank. The natural pressure build of a tank at 50º is essentially the same as a tank at 100º. Either way when PROPERLY filled (i.e. not saturated, about 80% "full") it should build about 50psi in 24 hours. Anything more than that is related to the integrity of the vacuum inside the tank than external temperature. It's not unusual to have older tanks with weaker vacuums build up 50psi in 8-12 hours, anything more than that and it's in need of getting inspected and re-pulled. Of course that all costs money and right now most suppliers just don't care. If you lose more than 50% of your liquid to venting in 72 hours complain, otherwise use it faster or accept that even when you lose 50% to venting it's still cheaper than compressed tanks.

[n3rd]

also try demanding better tanks, it worked for me. my supplier has some customers that just don't care about the condition of the tanks, but when i'm given a tank in good shape i get almost 2 months working time out of it. i spoke with my supplier (many times) and now they finally have a smaller fleet of tanks in good shape for myself and my shopmates. economizer is the one on the far right in your last picture, look for numbers on the set screw covered in white plastic.

[funksizzle]

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[chrissyo.]

Right on thanks for all the replies. I unscrewed the one that you guys said was the one i was looking for this morning before i started working and i think its doing what it should. There weren't any numbers marked on it but i just backed it out a good little amount. The tank was at about 100 psi when i started this morning and throughout the day it would never go below 50psi and was consistently holding at that pressure while i worked. And if the economizer works the way i think it does, then if i had it screwed in the amount for say a 100psi setting the pressure on the tank would have never dipped below 100psi right?? Because once it would start to go below 100psi it would squirt a little liquid in the pressure builder (or whatever it does i'm not sure if that's really what is going on) and let it evaporate to bring it back up to the economizer setting of 100psi. Am i kind of on the right track with that?? Anyways, thanks for the replies, ill be eager to see in the morning if it builds as fast..

[Greymatter Glass]

Yep. The economizer is a bypass (usually) to the main pressure builder knob. It attempts to keep the head pressure at a constant level by allowing some liquid into the pressure building coils on demand.

Some tanks it acts as a complete bypass, others it only works with the pressure builder on.

What you have is basically both systems, which seems rather pointless to me, but I'm sure there's a reason.

[Firekist]

quite a few of the 180L tanks are exactly like that. quite a few times there is tape or whatnot put over the "economizer" screw, and often there are no markings on that screw.
the higher capacity, newer tanks have the one regulator setup, with the numbers for you to adjust the head pressure.

[nodice]

Your tank shouldn't vent til at least 230psi. Having it at 100psi instead of 50 makes it easier for the reg to maintain pressure at say 35psi.........

[dnug42]

I got a newer tank and it has about 5 inverted bolts you can turn with a allen wrench, and a list of diffrent setting below the econ. and the econ. itself is super user friendly- jus turn to your desired setting...but the bolts...whuts up with those? its says "tighten screws by numberd order'- and list few diffent setting...? looks tempting but i'll wait...

[dnug42]

pic47745

[funksizzle]

47893

[Greymatter Glass]

I got a newer tank and it has about 5 inverted bolts you can turn with a allen wrench, and a list of diffrent setting below the econ. and the econ. itself is super user friendly- jus turn to your desired setting...but the bolts...whuts up with those? its says "tighten screws by numberd order'- and list few diffent setting...? looks tempting but i'll wait...

Don't mess with those bolts, they're not for the economizer...

I'm not certain what they're for. I suspect they have to do with the liquid level gauge or some kind of cover plate to a service port for the vacuum maybe... but whatever they're for, they're not related to the normal every day use of the tank. The numbers (25 inch-pounds) refers to the torque setting. If you don't have a proper torque wrench you won't be able to properly tighten them anyways. Generally torque specified bolts in a given pattern/order are used on high pressure flange fittings, loosening these while the tank is under pressure could cause a leak, and even damage the tank or result in a rupture of the flange if tampered with.

Cryogenic cylinders are not "consumer" items, they're federally regulated industrial equipment that, were you to work under the auspice of OSHA/NIOSH, would usually require certification/qualification training to handle. We're LUCKY that welding suppliers trust us with these things.

They are generally fairly simple to operate safely... that doesn't mean you can just experimentally mess with things if you don't understand they're function.

Next time I am at AirGas I'll ask the plant manager what they're for... if someone actually knows and can cite a reference from a manufacturer please do so.

-Doug

[Greymatter Glass]

Interesting. I'd say just turn your allen wrench from 3 oclock to 4:30 1-4 at a time. Each time starting in the same spot. Ending at 4:30, little at a time. Also, probably don't turn too much, just in case the user can't get it back.

Funksizzle, seriously... stop giving ANY advice on this forum. You do NOT know what you're talking about and you constantly give advice that could result in serious damage to equipment, injury, or worse. I have seen you do it multiple times.

If you don't know an answer to something DO NOT GUESS AT IT.

There are PLENTY of well informed people here who DO know what they're doing, or at the very least know when to advise caution over experimentation for you to ignorantly tell people what they should do when you yourself don't actually have a clue.

Post Count is not a contest.

Being helpful is not a contest.

If you don't know, don't post.

[hashmasta-kut]

pic47745

this tank you have here is usually the good type. in order to not make it build much pressure put the silver cap down by rotating whichever way makes it go down. the higher the number it shows the higher the pressure the tank will pressurize to. it only needs to be at around 80 in my experience to be good enough unless you might be raging multiple torches.

[funksizzle]

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[dnug42]

thks doug- i was def. not planning on ajusting them, more interested in there function...always a reliable source of info. cheers!

[dnug42]

one more qusetion guys...at any point as the tank gets lower in gas do you raise the economizer to a highers setting?

[Greymatter Glass]

no....

[somewhere]

one more qusetion guys...at any point as the tank gets lower in gas do you raise the economizer to a highers setting?

I understand Doug's answer but want to expand. (no pun intended)

One thing to consider as the tank gets lower the liquid will take more time to boil and biild head pressure and it may not keep up. In return if you have the head pressure turned way down you may end up being starved for oxygen. You can either turn on the pressure builder and let it build before or during work or turn up the economizer valve. Unless you are a high demand shop this may not be an issue but in a larger shop it may.

[dnug42]

I seem to have issues at the end of a tank...like the last few days its going. working gets really difficult- like i feel like its my first time on a torch...nothing melts right, stuff is crackin left an right... I how do you jus get the last life out of a tank, cause there is still some reading on gage... the full/empty gage is in E but that section has a 1/4 reading till its totally kicked...I know they are not totally accurate, buttttt ?