Brewing Master

Question:

What should the high side gauge read for a full 20 LB tank?  I am just starting kegging and picked up one last week and it  is only showing 700 PSI.  Does this sound like a lite fill to you? Thanks, Jerry

Response:

My understanding is that the vapor pressure of the tank will stabilize and remain constant until all the liquid CO2 has vaporized, at which time the pressure will begin to drop.  Thus, pressure won’t tell you if you have less than a full tank.  My experince with my airbrush on a CO2 tank is consistent with this (although I’ve never been able to hear liquid CO2 sloshing in the tank). What should the high side gauge read for a full 20 LB tank?  I am just starting kegging and picked up one last week and it  is only showing 700 PSI.  Does this sound like a lite fill to you? Thanks, Jerry

– Todd Enlund      "Bandits at 3 O’Clock"      "Roger.  What should I do ’till then?"

Response:

What should the high side gauge read for a full 20 LB tank?  I am just starting kegging and picked up one last week and it  is only showing 700 PSI.  Does this sound like a lite fill to you? Thanks, Jerry

No, it sounds right. The high side won’t tell you much until the tank is just about empty. The best way I know of is to know the tare (empty weight) of the tank an subtract it from the weight of a charged tank. The only thing I find the high side of a CO2 tank is good for is that you know when it’s too late to run out and have it refilled Medford, NY swap net.optonline to reply via e-mail

Response:

It will depend on the temp of the room. On hot days, you might see it peek to 800psi. On cold days or by storing it in the fridge, you might see it below the red line (<500psi). So you’re good to go. The worst thing is that when it drops because it’s running low, it drops fast. Burp, -Dan — Replace nospam with msn to email me.

– Hide quoted text — Show quoted text – What should the high side gauge read for a full 20 LB tank?  I am just starting kegging and picked up one last week and it  is only showing 700 PSI.  Does this sound like a lite fill to you? Thanks, Jerry

Response:

Is this tank and gauge also refrigerated ?    Gauges are calibrated at room temperature for one.  Also the vapor pressure of CO2 changes with temperature.

Yes it is in the refrigerator for now. And the pressure dropped about 100 PSI from the cold. Jerry

Response:

In that case, they’re probably better off buying cryogenic CO2 in VGL’s…Some restaurants get their CO2 for soda pop delivered by truck…tank truck, that is.  I used to get nitrogen, argon, oxygen and hydrogen delivered that way (the H2 was gaseous, though).  600,000 cubic feet at a time. One nice thing about a VGL is there’s a little plastic dome on top with a gauge, run off an internal float, that tells you how much CO2 is in there. Regards, Mike Sharp

– Hide quoted text — Show quoted text – The high pressure gage is probably very useful in a commercial operation where running out of CO2 could have dire financial consequences. — Dan Listermann Check out our E-tail site at www.listermann.com Free shipping for orders greater than $35 and East of the Mighty Miss. Since the high pressure gauge doesn’t seem to serve any purpose other that telling you that you have gas in your tank (but not how much) is it really necessary? Mike — **Remove the obvious when replying** Basically, ignore the high side gauge. The other problem with the high pressure gage is that it sticks out the side and is very vulnerable to being damaged so much so that there are "gage cages" sold to protect them.  The low pressure gage is not nearly as vulnerable to damage. How true. My son knocked over my 5#  which I thought I had put in a safe spot when I removed it from a keg I had just emptied. The high side gage was smashed. I removed the glass and straightened things out the best I could and got a reading. I bought a new gage and replaced the old one. If I had known then how useless it is, I would have saved the money and used the bent up gage. Medford, NY swap net.optonline to reply via e-mail

Response:

Since the high pressure gauge doesn’t seem to serve any purpose other that telling you that you have gas in your tank (but not how much) is it really necessary?

I would say it’s completely unnecessary.  Buy a regulator without one, they’re usually cheaper. John. —                            *** John P. Kolesar ***                          *** Valley Mead Brewery ***

Response:

The Schwinn bike shop the next town over doubles as a paintball retailer.

A lot of hobby shops cover more than one subject.  Anybody thinking of going into the homebrew shop biz should give this careful consideration.  We manufacture here as well as retail. — Dan Listermann Check out our E-tail site at www.listermann.com Free shipping for orders greater than $35 and East of the Mighty Miss. – Hide quoted text — Show quoted text – They fill all 3 sizes for $2. Mike

Response:

Where do you get the 9,12, or 20 oz. canisters refilled?  How much is it to refill them?

The Schwinn bike shop the next town over doubles as a paintball retailer. They fill all 3 sizes for $2. Mike

Response:

Where do you get the 9,12, or 20 oz. canisters refilled?  How much is it to refill them? The Schwinn bike shop the next town over doubles as a paintball retailer. They fill all 3 sizes for $2. Mike

Very nice. $4 by me. Medford, NY swap net.optonline to reply via e-mail

Response:

 I guess a scale is the only way to know.  Thanks for all the information. Jerry

Response:

Is this tank and gauge also refrigerated ?    Gauges are calibrated at room temperature for one.  Also the vapor pressure of CO2 changes with temperature. jp – Hide quoted text — Show quoted text – What should the high side gauge read for a full 20 LB tank?  I am just starting kegging and picked up one last week and it  is only showing 700 PSI.  Does this sound like a lite fill to you? Thanks, Jerry

Response:

What should the high side gauge read for a full 20 LB tank?  I am just starting kegging and picked up one last week and it  is only showing 700 PSI.  Does this sound like a lite fill to you? Thanks, Jerry

To make a long story short, the tank gauge is basically useless. It is capable of indicating only two things "some" and "empty" and, even without it you’ll know when it’s empty ’cause you can’t get anything out of it ;-(. Now, here’s the long story . In your cylinder, the CO2 is in both liquid and vapour form. As long as both liquid and vapor are present, the pressure in the tank and on the gauge will depend entirely on the ambient temperature. The pressure you read on your gauge is the vapour pressure (the equilibrium pressure between the CO2 liquid and vapour). At 70