# Proximity of aux tank to compressor



## Dnewman (Jun 6, 2021)

Trying to optimize my setup and could use some input. I use a compressor that feeds air to a nitrogen generator which is used for scientific instruments(gas chromatograph). The inlet pressure of the nitrogen generator is 90 psi. The compressor and nitrogen generator are on 24/7. Currently the compressor kicks on every couple of hours and runs for 30 seconds or a minute. When this happens I get slight pressure blips on the instruments.

I have a 2 hp California air tools 10020c compressor it has a 10 gallon tank. I just bought a 20 gallon auxiliary tank. My thought was the extra storage capacity would help stabilize line pressure. I have the compressor in the basement and have copper tubing running from basement up the side of the building into the room with the instruments a distance of around 75 feet.

The questions I have is should the aux tank be in the basement with the compressor or in the room with the instruments? Does it make any differance?

Also wondering if the air line going from basement to outside and back inside will be an issue. In the pacific northwest where temp is pretty moderate but does get below freezing on occasion.


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## iowagold (Jan 22, 2020)

you might need a dryer for the air....
low humidity works the best!
make sure the feed line is over sized by 50% or more of the cfm you need on the inlet for the N generator.
and 2 x if the line length is long.

so on the N generator how many cfm does it require when running?


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## Marlin (May 25, 2015)

Dnewman said:


> I have a 2 hp California air tools 10020c compressor it has a 10 gallon tank. I just bought a 20 gallon auxiliary tank. My thought was the extra storage capacity would help stabilize line pressure. I have the compressor in the basement and have copper tubing running from basement up the side of the building into the room with the instruments a distance of around 75 feet.
> 
> The questions I have is should the aux tank be in the basement with the compressor or in the room with the instruments? Does it make any differance?
> 
> Also wondering if the air line going from basement to outside and back inside will be an issue. In the pacific northwest where temp is pretty moderate but does get below freezing on occasion.


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## Marlin (May 25, 2015)

Well, I will try this again, my first reply seems to not include what I typed, only a portion of the original posting.

It sounds like what you are experiencing is normal, you are seeing pressure fluctuations when the compressor kicks on because the "On" pressure setting is too close to the input pressure requirement of your nitrogen generator.

Several possible solutions might include increasing the pressure settings on the control switch. If there is a regulator between the compressor and the nitrogen generator, your input pressure to your regulator may be low enough before the compressor kicks on that the regulator no longer is capable of providing the 90 PSI that you are looking for.

If your nitrogen generator MUST have a nice smooth non-fluctuating 90 psi input, then you need to have a regulator in front of it, between the compressor's tank and the generator and the input to the regulator must never get below the amount needed for the regulator to work properly. Depending on the regulator, it may require that the output of the compressor tank never go below maybe 100 pounds at a minimum. Possibly, depending on the particular regulator, it's minimum input pressure may be even higher.

What kind of pressure are you looking for on the output of the nitrogen generator? Maybe (?) you could get by with a little less pressure to the instruments? If so, put a regulator after the nitrogen generator, regulate it to several PSI lower than what it is now, the regulator would smooth out the "Blips".

I doubt very seriously that the addition of an auxiliary storage tank will change anything. That is assuming that what you are having is a input pressure to the generator drops too low before the compressor kicks on. If that is the case, it will still do it, but, fewer times per day. Adding the second tank will make the compressor run longer, but, less often, but the blips you see will still be there every time the compressor needs to come on.

Marlin


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## iowagold (Jan 22, 2020)

2 things light be nice on his system
a pressure gauge right at the feed to the n generator with a flow gauge to watch the cfm to see if it is a low flow issue or a pop off back in the feed line issue...
and yes a regulator just before the input at the n generator with the proper rating for the cfm required.

dry air helps on the o2 and the n generators....
less water to deal with...
but a real good dryer is pricey!
and expensive to run unless you have the dry elements that self regenerate.


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## Dnewman (Jun 6, 2021)

Thanks for the input, very much appreciated. Right now the output of the nitrogen generator is going to three instruments that each require about 400 ml/minute. The generator output on my meter is 3500 ml/minute. 

I recently purchased the Tsunami regenerative air dryer which I will add to the system along with an inline regulator/flow gauge between generator and instruments and one right before the generator input. I'm going to hold off on hooking up the aux tank since it doesn't sound like it will make much differance with the issuebim having.


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## iowagold (Jan 22, 2020)

sounds like a plan!


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