reading gauges

Discussion in 'Carbon Dioxide (CO2)' started by neelhound, 13 Jul 2009.

  1. neelhound

    neelhound Member

    Hi i know i probably should know this...but i dont get the gauge that goes from 1-4. ive heard its the low pressure side- if so why is it required.Ive also heard its psi-but i wouldve thought that psi is loads more than bar unless 1.5 is 1500. I just need a bit of an explanation on this is possible :S puzzling
  2. Steve Smith

    Steve Smith Member

    Leamington Spa, UK.
    You don't necessarily need it, but it's good to know how much the pressure is being reduced. Some regulators have an adjuster so that you can control the low pressure side. I've never really figured out why to be honest. Someone will no ddoubt be able to tell you. I've always been told that it should be at approx 1 bar.
  3. gratts

    gratts Member

    The gauge with the larger scale, probably reading around 50-60 bar is the pressure inside your cylinder.
    Atmospheric pressure is 1 bar, so most cylinders are compressed 50-60 times that of atmospheric pressure when full. Obviously this falls as gas is expelled.
    The smaller scaled gauge, which on my regulator reads from 0-4 bar(never PSI!) is the output pressure which the regulator reduces the CO2 down to. Anything around 1-2 bar is fine.
    Providing the low pressure gauge isn't telling you anything silly then just rely on bubble count and ignore it.
    What regulator/setup do you have?
  4. neelhound

    neelhound Member

    jbl easy set 1
  5. CeeJay

    CeeJay Member

    Surrey UK
    Hi neelhound.
    As others have explained, the 2nd gauge is measuring Bar.
    To assist in your understanding, PSI (pounds per square inch), is not loads more than Bar as you suspected. The general rule of thumb is that there are 14.5 PSI to 1 Bar, give or take a few decimal places.
    I don't mean to sound condescending in any way, I'm just trying to pass on knowledge that I've gained during my working life using compressed gases and air.
    On a cautionary note, a quick glance at the calculator will tell you that a CO2 bottle filled to 60 Bar equates to approx. 870 psi. Seriously, enough to take your head off. I've seen a few 'mishaps' with compressed gases and air over the years and they are not a pretty sight.
    To put this into perspective, you may have heard the almighty bang when a car tyre explodes, well that's only filled to around 2 to 2.2 Bar. Imagine that bang amplified 30 times. Stand well clear and get the ear plugs out. :lol:
    Another word of advice I can offer is that if you get your CO2 cylinders refilled, don't let them rattle around in the boot of your car and transport them with the horn fitted.
    If one was to accidentally discharge in the boot of your car without without the horn fitted, you would have a jet of CO2 at 870 psi which is enough to blow your boot lid off. :eek: and at the same time turn your cylinder into a rocket. With the horn fitted, the gas first encounters a right angled bend which reduces the pressure some and then it is reduced even further by being 'spread' over a wider area via the horn.
    Sorry, I seem to have gone off on one here but all I can say is treat your CO2 cylinders with respect and you should have no problems.
    Hope this clarified your original query anyway. As I was once told at college, "It's easy if you understand it, if you don't understand it, it's impossible". This statement can be applied to anything in life, it's a bit like this planted tank game really. :lol:

  6. neelhound

    neelhound Member

    ok thanks! they also have the power to kill fish...but i use the disposable ones that get delivered to me
  7. GreenNeedle

    GreenNeedle Member

    Lincoln UK
    The disposable ones will read approx 60bar when connected up to the reg.

    It will remain at 60bar until it is very nearly empty. This is because inside the cylinder is liquid. It turns into gas in any area that is not liquid. This of course is at the top which is why you stand the cylinders up. As gas is release more liquid turns into gas and fills the void. Once there is not enough liquid left to maintain the void then the pressure reduces.

    The low pressure gauge is needed because it is showing at what pressure the gas is being released. We set it between 1.5 and 2 so that there is enough pressure for the needle valve to maintain consistency without there being too much pressure that each slight movement of the needle valve makes a huge difference.

    If we set it too low then the needle valve's use can be negated sometimes as the pressure can waver around a little.

    If we set it to 1.5-2 then it means the level stops wavering and that each incremental movement of the needle valve will increase/decrease slightly. 1mm movement could be the difference between 1bps and 1.1bps :)

    If we were to set it at 4bar or higher then each incremental movement of the needle valve could mean it was too hard to increase/decrease at slight amounts. turning 1mm could be the difference between 1bps and 4bps. Maybe even more of a difference than that :eek:

    If we were welding we would fully open the regulator and let the plant control the output. In our situation we don't fully open the regulator. We open it until 1.5 - 2bar is maintained while the unit is working. It may rise slightly to 3 or 4 when the solenoid shuts off but that is fine.

    The pre-set ones are often set at 2.2bar apparently but there is a hidden screw somewhere (often under a label) that can be used to adjust it down. I don't think that is necessary though. I run mine at 2 and it goes up to about 2.5 when off.

  8. neelhound

    neelhound Member

    wow thanks really helpful i love this forum

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