Portable compressor and extra tank plumbing - parallel or series

by Mike
(Salt Lake City Utah)

Just purchased a name brand twin tank wheelbarrow compressor with 11.8CFM at 90PSI and 9 Gal tanks.

I want to run 3/4 inch Impact ratchet rated at 6.2 CFM average and under full load 22 CFM.

To help with the CFM under load I want to add an extra tank and will run all 1/2 inch hoses.

Question should I route the extra tank so its parallel to the installed tanks before the regulator or should I use the extra after the regulator in Series with the main tanks?

Bill says....

Mike, for those that are curious, here is my understanding of what you are asking:

Should you plumb the extra tank beside the existing one, with both tank discharge lines running through a single tee to one regulator which then supplies the compressed air to the air line to your air ratchet? To my mind, this is a parallel installation since both tanks can supply air to the circuit independently of the other.

Or, do you run the air from the compressor air tank directly into the secondary air tank, and then from the secondary air tank through the regulator to the air line to the ratchet, to me, that's a series air circuit.

Having said that, regardless of whether you plumb in parallel or series, depending on how long you need to run your ratchet under load, I fear that your air compressor may be too small, almost regardless of how big the secondary tank is.

You say that you " want to run 3/4 inch Impact ratchet rated at 6.2 CFM average and under full load 22 CFM" but you don't say at what pressure.

If the pressure demand is low, you might, and I stress might, get away with your plan. If the ratchet pressure is up around the 80-90 PSI range, I don't think your compressor will cut it in terms of adequate supply, almost regardless of how big your secondary tank is.



Comments for Portable compressor and extra tank plumbing - parallel or series

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Aug 17, 2011
Air hose suggestion
by: Rager

3/4 drive impact ought to be run with a one inch hose. Hose size smaller doesn't flow enough air to run the impact satisfactorily.

May 08, 2011
additional info and plan of action
by: Mike - original poster

Additional info:
The impact wrench is operated at 90PSI, max load is in burst to bust a nut free. After that I run it off and move to the next nut. Understand that it may need a pause to refill the tanks.

The compressor is Ingersoll-Rand and rated at 100% duty cycle so running the compressor hard will not be the biggest issue.

The compressor will be used 2-3 times per week at remote sites changing truck tires torqued to 500 ft-lbs and then driven around for a year. The point is to use the impact wrench rated at 1200ft-lbs to make life easier. I now do it with hand tools, big breaker bar and 2000 ft-lbs rated 4x torque multiplier.

Plan of action:
The location of the tank in relation to the regulator is key more than the order of the tanks.
Thank you for pointing that out.

This would mean I should add a T-fitting before the regulator and splice the tank into the system.

May 07, 2011
Air tank capacity
by: Buster

All the comments are true, if you are planning to use the air tool continuously at full load. If you use the ratchet at nominal load with a spurt of full load demand for only a few seconds, like breaking a nut or bolt loose, then spinning it off, the parrallel combination before the regulator would give you more time, volume wise, between full load demands and full load supply and it all depends on the demand you put on the system. The extra tank, connected either parallel or series, before the regulator, would be a better choice than after the regulator. This gives you higher pressure storage, resulting in more volume at lower pressure, after the regulator.

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