weird CO2 problem

[hwchoy]

I am having this really weird problem with my CO2, any ideas much appreciated.

I am using a pressurised cylinder with JBJ regulator and solenoid, which goes to a one-way valve, bubble counter and difussor (ADA pollen beetle). The whole set up was working fine until my last top up (done at Bioplast).

After connecting the regulator back to the cylinder, everything will work with external pressure at about 20psi. This then slowly falls to less than 10psi in a space of an hour or two. I checked everything for leaks and even relaid the tubings with new polyurethane ones, still same symptom. I empirically found that if I loosen my regulator from the cylinder and tighten it back everything goes to normal and repeats itself (i.e. pressure falls from 20 to 10psi). Internal pressure is about 800psi.

Finally I put a straight length of tubing (i.e. no breaks) direct from the regulator into the tank, amazingly the same problem. So the tubing fittings clearly isn't the problem!

If I loosen the regulator and retighten the same thing will again go back to normal and repeats itself. When the solenoid goes off the pressure goes back up to 20psi. Any ideas!!

[PeterGwee]

Its the meter problem....I had such problems when I use the JBJ regulator last time also...weird huh. Suddenly, the external pressure will drop...disconnect the regulator and fix it back and the pressure will go up again..after a few days, pressure drops again. The worst thing about this regulator is that it will exhibit end of tank dump..(lucky was around to fix the problem or else fishes will be in heaven already.)

[jameshoftiezer]

Sounds like a bad regulator.
I've heard of something similar in industry and it comes down to the quality of the equipment.

[bclee]

I think this is pretty normal.

When the solenoid is shut, the presure will build up slightly at the output end.

If you are using a diffusor, when the solenoid valve open, the CO2 will slowly eject the water from the pores of the glass/ceramic. As this go one, the presure will slowly lower to the set output pressure as the CO2 forces through the pores.

BC

[hwchoy]

but BC, the output pressure falls so low that the bubble rate is less than 1 bps, even if I open the needle valve all the way!

if this is a fault is it repairable or do I chuck the regulator, and if I do that can I keep the solenoid?

[tawauboy]

it seems that your regulator is not working properly.
it is not doing it's job of maintaining output pressure.
don't know is anyone is capable of repairing a pressure regulator but i don't think it is advisable to repair one. better get a new one.
if not done correctly, the 800++ psi of co2 may be dumped into your tank.

if your solenoid is detachable from your current setup, i am pretty sure that it can be reused. why not check with the lfs where you plan to get your next regulator.

[bclee]

I have a JBJ regulator. I've just come home and observe my regulator.

When the solenoid valve shut, the output presure rises to about 15+ psi. When the valve open, the output pressure droped immediately to 10psi (I am using a flipper).

So I think this phenomena may be normal. Could it be the diffusor is choked?

BC

[hwchoy]

I took a closer look at the regulator. The internal pressure is actually a shade above 1000 psi!! [] And with the solenoid closed the internal pressure is 40 psi. I'd thought 1000 psi is way too high, perhaps I should let out some gas? You think that could've damaged the regulator? The diffusor isn't choke as I have tried it with a clear tubing without even an airstone.

[kaipium]

I think figures like 800+psi or 1000+psi are all wrong. The CO2 cylinder is not rated to such high pressures. Typical pressure should be around 50 to 90psi and 100 would be max in my opinion.

There are usually 2 scales in the main pressure gauge and they are psi or kg/cm2. 14.5 kg/cm2 equals 1.0psi. So figures like 1000 should be kg/cm2 and ti should actually be around 70+psi.

The other pressure gauge should be in kg/cm2 only nad mine is currenly redaing only 2 to 5 KG/CM2 which is around 0.15 to 0.35psi.

Go see your pressure gauges carefully.

And yes, if the diffuser is chocked, the back pressure from the diffuser can be up to 3-5 kg/cm2 easily. You only have to worry about the bubble count and how much the small gauge correspond to the bubble count. Then you are okay. There will be some setting where if you set the main pressure gauge too low, there is not sufficient pressure equalisation to open the solenoid valve.

I hope this info is useful to all.

Thanks

[hwchoy]

ahem, you've got it reversed. 1000 psi = 70.30695796 kg/cm²

a car tyre runs at around 30 psi, its made of rubber. [:]

[bclee]

1000psi is actually correct.

Vapour pressure of CO2 at 28.4°C is 1009.7psi. (@23.4°C VP=900.28psi) The cylinder can take much higher pressure than this. So the high pressure side should read around 900~1000psi depending on surround temperature.

The low pressure side is about 10psi according to my JBJ regulator. (Atmospheric pressure is about 14.7psi. So I guess the output pressure should be 10+14.7psi.)

BC

[hwchoy]

looks like time to shop for a regulator, any one recommend one that will take a solenoid (the type found on the JBJ regulator)?

[bclee]

Choy, base on your description, I do not find any fault with your regulator. Is it possible that your diffusor is choked?

BC

[bclee]

opps. You mentioned that you checked without the diffusor. Ok... solenoid problem... maybe.

How long have you been using the regulator?

BC

[bclee]

opps. You mentioned that you checked without the diffusor. Ok... solenoid problem... maybe.

How long have you been using the regulator?

BC

[kaipium]

choy, u r right about the conversion. It should be i kg/cm2 to 14.5psi.

Must be too early in the morning..........should have my coffee first before replying.

But bclee, I still do not think that the pressure in the cylinder will be much more than 100psi which is already about 7 bars. For a cylinder to manage 70 bars, I think it is a professional job.

[tawauboy]

it is true that a co2 tank pressure can be up to 1000psi.
else there wouldn't be 'horror' stories about tanks turning into 'rockets'.
and also soxal will not refill those tanks that fail their pressure test.

[hwchoy]

solenoid is working fine, it does open and close. problem is the flow rate, even with the fine adjustment fully open, the flow starts falling from many bps to less than 1 bps in an hour or so. This regulator isn't new (about 1 year) and this is not normal behaviour []

[bclee]

Damn! I am using a JBJ regulator. But I know JBJ changed the source of regulator manufacturer. Choy, does your regulator come in a yellow box or white box?

Kaipium, the cylinder can definitely take way beyond 1000psi. That's why one have to be careful while handling the cylinders. Toppling the cylinder can break the regulator and sending the regulator or cylinder shooting out your window.

BC

[hwchoy]

BC, the regulator came fitted onto the tank with solenoid, didn't really notice the box but probably not yellow. got it from K&K in Tampines St 21 early last year.