Parallel or Series, which is better?

[Daniel_LaFleur]

Originally Posted by diesel

Sorry for not being clear.

Yes, I am talking about pnuematic tanks.
We have one piston on our robot.
Will putting the tanks in parallel provide more force?
Will putting them in series make the pressure last longer?
And any other facts would be great.

Thanks.

OK, the simple answer is ... it depends.

It depends on what is the controlling orifice (what has the most restriction or lowest CV) as to whether series or parallel is better. squirrels' answer assumes that the regulator is the controlling orifice, which is generally not true. Usually the valve has the controlling orifice.

Changing the path at the controlling orifice (IE splitting the flow path and having it run through 2 valves) will garner you the biggest bang for the buck.

Originally Posted by David Brinza

Speaking of parallel:

Is it legal to use two regulators in parallel to provide 60 psi to pistons from the 120 psi tanks? Twice the flow would be available...

I believe that the regulators are a 'bleed' type which means that when the output overpressurizes (goes over the setpoint pressure of the diaphram) the regulator bleeds off the excess pressure through a pressure relief vent. This would mean that if both regulators weren't set EXACTLY at the same pressure (no easy feat) then one would continue to supply air while the other would be venting it, and that would tax your on-board compressor.

[Gary Dillard]

Originally Posted by Daniel_LaFleur

OK, the simple answer is ... it depends.

It depends on what is the controlling orifice (what has the most restriction or lowest CV) as to whether series or parallel is better. squirrels' answer assumes that the regulator is the controlling orifice, which is generally not true. Usually the valve has the controlling orifice.

We're splitting hairs here, but in reference to his question - should the tanks be in series or in parallel, the fact that the valve is the controlling orifice has nothing to do with the answer to that question. By the rules, all the flow from the tanks has to go through a single tube into a single regulator and then out to the system. Regardless of whether you put one valve or 10 valves downstream, the rate at which air will go through that one tube and one regulator is not dependant on whether the tanks are in series or parallel. The storage volume will discharge at the same rate.

[Los Frijoles]

All that tanks really are is very large diameter tubing. Since Air is a gas, it will flow freely to fill up the entire space that it is given, so placement of the tanks does not have a serious effect on the way the air flows. Only in applications where the movement of air is critical and at high velocity like pneumatic potato guns does tank placement matter.

[Daniel_LaFleur]

Originally Posted by Gary Dillard

We're splitting hairs here, but in reference to his question - should the tanks be in series or in parallel, the fact that the valve is the controlling orifice has nothing to do with the answer to that question. By the rules, all the flow from the tanks has to go through a single tube into a single regulator and then out to the system. Regardless of whether you put one valve or 10 valves downstream, the rate at which air will go through that one tube and one regulator is not dependant on whether the tanks are in series or parallel. The storage volume will discharge at the same rate.

My answer is correct.

No valve in the KOP will flow gas faster than the tubes supplied, thus the tubes are not the controlling restrictor.

No valve will flow anywhere near the flow capacity of the regulator, thus again, the controlling restrictor is the valve.

Putting tanks in parallel will do nothing if the controlling restrictor is not the flow orifice from the tanks.

My explaination was to show how he could get higher flow and to point him in the proper direction as to why the flow through his pneumatic system is what it is.

His question was trying to flow gas faster, thus my suggestion to parallel the controlling restrictor, not the tanks or the regulators.

It's not splitting hairs ... it's the physics of gasses and I'm trying to get him to understand the answer, not give the answer to him.

[David Brinza]

Originally Posted by Daniel_LaFleur

I believe that the regulators are a 'bleed' type which means that when the output overpressurizes (goes over the setpoint pressure of the diaphram) the regulator bleeds off the excess pressure through a pressure relief vent. This would mean that if both regulators weren't set EXACTLY at the same pressure (no easy feat) then one would continue to supply air while the other would be venting it, and that would tax your on-board compressor.

I think you're right about two regulators on a common 60 psi circuit.

I'm asking whether it's legal two have two independent 60 psi paths, each with its own regulator, valve and piston, operating off of a common 120 psi source.

[dlavery]

Originally Posted by David Brinza

I think you're right about two regulators on a common 60 psi circuit.

I'm asking whether it's legal two have two independent 60 psi paths, each with its own regulator, valve and piston, operating off of a common 120 psi source.

For the answer to that question, you may want to look at this Q&A answer.

-dave



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[David Brinza]

Originally Posted by dlavery

For the answer to that question, you may want to look at this Q&A answer.

-dave



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I couldn't ask for a more clearly stated answer to my question. Obviously, I should have consulted the official source FIRST!