# how to declare air pressure for a double acting cylinder?



## bemegopi (Mar 19, 2014)

My basic question is,

I am using one Double acting cylinder
bore-25mm
stroke-125mm

Now i set a 5 bar pressure. now it is working perfectly

my question is it is possible that air pressure reduces to 4 bar?

I want to know how we declare the air pressure for that double acting cylinder??? theoritically??


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## corey872 (Jan 10, 2010)

I think we might be dealing with a bit of language barrier. I'm taking 'declare' to to mean 'calculate' ? Based on that and the fact you say the cylinder works perfectly at 5 bar....

For any given air pressure and given diameter of the piston, the air cylinder will put out a given force which can be calculated.

So:

Given 25mm diameter cylinder, find the area of the piston:
25mm x 3.1415 = 78 square mm piston area

Given 5 bar pressure, find the force exerted on 78 sq mm:
(knowing 1 bar = 0.1N/mm2)

0.1N/mm2 x 5 x 78 = 39N force, or about 4kg force​
Now, if you lower to 4 bar pressure, with the same cylinder area:

0.1N/mm2 x 4 x 78 = 31N force or about 3kg force​
So lower pressure would result in less force the cylinder is able to move. This may result in slower operation or might stall the cylinder, depending on exactly how it is configured. For instance, if you have the 4kg force lifting a 2kg object, then you lower the force to 3kg, then the object moves slower. But if you have 4kg force moving a 3.5kg object, then you lower the force to 3kg, the object can't move at all.

This will also change slightly on the 'rod' side of the cylinder as the area taken up by the rod doesn't apply force, so you have slightly less force in the 'retract' side.

Hope this helps.

(* standard disclaimer...early morning math (and metric at that) may be error prone!)


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## bemegopi (Mar 19, 2014)

*thank you corey 872*

its very much helped for me.

Ok i am using 5 bar air pressure, now i will change the air pressure to 4 bar. the power consumption of the compressor will be reduced or not? if power consumption of the compressor reduced can u give me the details


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## Hippofeet (Nov 26, 2012)

Hmmm. The plot thickens...


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## bemegopi (Mar 19, 2014)

*plot thickness means?*

i didnt able to understand clearly about plot thickness. can you tell clearly for me??


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