Operating pressure

wormvortex

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Does increasing the operating pressure on the regulator cause
Gas to be consumed any quicker? And is there any benefit of increasing the operating pressure?
 

Tom Raffield

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My bazooka atomiser won't work unless operating pressure is really high. I control the bps so doubt the higher pressure uses gas any quicker.
 

Zeus.

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Does increasing the operating pressure on the regulator cause
Gas to be consumed any quicker? And is there any benefit of increasing the operating pressure?
Yes it does increase the CO2 used.

when you have high injection rates counting the BPS isn't possible


I use the working pressure to control the injection rate. Once I set the needle valves I haven't touched them in years, but have changed the working pressure
 

wormvortex

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even if you keep the BPS the same. For example is 1BPS at 1.5 bar going to use less co2 than 1BPS 2.5bar?
 

hypnogogia

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No. Flow rate (BPS) and pressure are different. If you keep the BPS constant but change pressure, the amount of co2 used remains the same. @Zeus changes the pressure to change the BPS, so his CO2 consumption changes.
 

Zeus.

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even if you keep the BPS the same. For example is 1BPS at 1.5 bar going to use less co2 than 1BPS 2.5bar?
Flow rate is a vector and BPS is a scalar as is pressure, if pressure increases and BPS is constant the fow doesn't necessarily remain constant, as the same size bubbles at higher pressure contain more gas, so each bubble contains more CO2.

So same BPS at lower working pressure means less gas IMO
 

rebel

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high injection rates counting the BPS isn't possible
It's definitely possible using a smart phone (fast FPS recording) and a simple timer.

I suspect that bubble size could differ according to pressure though. So simply counting bubbles may give you ball park; which is probably enuf.
 

JoshP12

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Hi @wormvortex,

Like others have mentioned, there are two ways on a regulator to control the injection rate (on the regulators I have used/seen). The needle valve is attached the bubble counter - my particular needle valve sucks and I use the knob exclusively. The knob (operating pressure) turns "into" the actual regulator. If you set the needle valve at whatever you want (open completely for example), you can increase the working pressure and increase the injection rate. If you push that black knob in all the way, you will likely blow the diaphragm of the regulator - so be cognizant of that.

To overcome ceramic (that is in many, if not all, diffusers), you will require a minimum working pressure to maintain a stable BPS (this is extremely important).

even if you keep the BPS the same. For example is 1BPS at 1.5 bar going to use less co2 than 1BPS 2.5bar?
I am assuming you are achieving this via opening the needle valve and reducing the operating pressure. Without discussing what will happen to the size of the bubble, if your system will collapse due to this, you should focus on surface agitation (overall increase in oxygen and stability ... high surface agitation will allow for a high injection rate which will make the system stable).

Like @Zeus. says, assume CO2 is free and use it like it is free. It's not worth dropping a small fortune on a CO2 system to be stingy with it.

Cheers,
Josh
 

zozo

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A bubble per second produced with higher pressure will most likely be a tad bigger bubble. :)
 

hypnogogia

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Flow rate is a vector and BPS is a scalar as is pressure, if pressure increases and BPS is constant the fow doesn't necessarily remain constant, as the same size bubbles at higher pressure contain more gas, so each bubble contains more CO2.

So same BPS at lower working pressure means less gas IMO
Yes, but velocity of said gas will decrease AFAIK. I think Bernoulli’s law is relevant here.
 

jaypeecee

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Hi Folks,

Do we not need to take into account the internal diameter of the tube from which a bubble emerges inside the bubble counter? This will determine the (starting) volume of CO2 in the bubble. I always have to remind myself of this as I sometimes overlook the obvious. It's relevant when comparing different setups as internal diameter of this tube possibly varies from one product to another. Or, maybe it's standardized - now that would be a first!

JPC
 

Zeus.

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Hi Folks,

Do we not need to take into account the internal diameter of the tube from which a bubble emerges inside the bubble counter? This will determine the (starting) volume of CO2 in the bubble. I always have to remind myself of this as I sometimes overlook the obvious. It's relevant when comparing different setups as internal diameter of this tube possibly varies from one product to another. Or, maybe it's standardized - now that would be a first!

JPC
I would of thought the needle valve is the the point of highest resistance esp when no atomiser is being used in a CO2 reactor, when an atomiser is fitted the resistance of the atomiser comes into play which will be atomiser dependant so both the needle valve and the atomiser will come into play.

But IMO increasing the working pressure will increase the injection rate on all setups, but will be needle valve and atomiser dependant
 

hypnogogia

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Hi Folks,

Do we not need to take into account the internal diameter of the tube from which a bubble emerges inside the bubble counter? This will determine the (starting) volume of CO2 in the bubble. I always have to remind myself of this as I sometimes overlook the obvious. It's relevant when comparing different setups as internal diameter of this tube possibly varies from one product to another. Or, maybe it's standardized - now that would be a first!

JPC
I think we can safely assume that diameter of tube will be a constant in the OPs question, so not sure how that would be relevant.
 

Zeus.

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I think we can safely assume that diameter of tube will be a constant in the OPs question, so not sure how that would be relevant.
For the rate of flow it will be irrelevant IMO, when we give patients O2 if they faint or other medical emergency we have it set at 15 litres per min and we use the same diameter tubing and a 2Kg cylinder would last about 20 mins. So at the rates of flow we us in our tanks the tubing diameter resistance doesn't matter.

The length does matter, as it takes longer to reach the atomisers working pressure.
 

jaypeecee

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Hi @hypnogogia
I think we can safely assume that diameter of tube will be a constant in the OPs question, so not sure how that would be relevant.
Perhaps I didn't explain myself well. I didn't mean to suggest that the OP's tube diameter was somehow going to change. All I was trying to say is that the diameter of this tube needs to be taken into account in some situations. As there was reference to bubble size below, that's why I mentioned it. That was all.
I suspect that bubble size could differ according to pressure though
JPC
 
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