How To Size A Refrigerated Air Dryer

Do you have water in your airlines? Is condensate from compressed air fouling valves on your manufacturing equipment or cnc machines? Are your employees complaining about water spraying from air guns instead of compressed air? If so, you lot demand an air dryer. Or some service on the i you have.
wet tank drain failure
Permit's presume you don't take ane only need i. For most compressed air applications, a refrigerated dryer is sufficient. Sizing a refrigerated air dryer is simple but usually disregarded, fifty-fifty by people in the air compressor industry.

For reasons I honestly don't know, most refrigerated air dryer specs are published based on 100 psi arrangement pressure, 100 F ambient temperature and 100 F compressed air inlet temperature. In 15 years, I've only sold one compressor geared for 100 psi. All others have been 125 psi with the rare exception of 150 psi for specialty applications.

So, let's assume you have a compressor that produces forty cfm at 125 psi. The compressor I'thousand referencing is an Atlas Copco, G7-125. This would equate to a 10hp rotary screw compressor. A quick glance at an Atlas Copco brochure volition show an FX4 dryer rated for 49 cfm with a 41 F dew point. That may look good at first just continue in mind the 100 / 100 / 100 conditions from above.

Atlas Copco G7-125 rotary screw compressor

There are three multipliers (as well called correction factors) to consider when sizing a refrigerated air dryer. Ambient temperature, inlet temperature, and inlet pressure. Atlas Copco refers to these every bit K1, K2, and K3, respectively.

Ambient temperature is like shooting fish in a barrel. You but need to know the highest temperature for your environment. For united states of america on the Texas gulf coast, we tin see temperatures budgeted 100 F in the shade. If the dryer is indoors or surrounded by other equipment it would be all-time to takes some temperature readings and determine the actual ambient.

Inlet temperature is the virtually hard. For an oil lubricated rotary screw compressor, the compressed air temperature is normally in the range of ambient plus 20 F. This is called approach temperature if you lot're wondering. For hot climates, this factor will get you if neglected. Reciprocating (piston) compressors accept a much higher discharge temperature. If a piston compressor doesn't have an integrated or stand-alone aftercooler, then a high inlet temperature dryer should be used.

Pressure is unproblematic. Just determine the force per unit area your organisation will mostly operate at and use the appropriate factor. Utilize the lower end of your pressure band since an increase in pressure equates to an increase in dryer capacity.

Here are the multipliers for the Atlas Copco FX dryers I referenced for this commodity.

Ambient temperature: 100 F = i, 104 F = 0.8, and 110 F = 0.74

Inlet temperature: 100 F = 1, 104 F = 0.82, 113 F = 0.69, 122 F = 0.58, and 131 F = 0.45

Inlet pressure: 102 psi = ane, 116 psi = 1.03, 131 psi = 1.06, 145 psi = 1.08, and 160 psi = one.i

The formula for actual chapters: Qactual = K1 x K2 ten K3 10 Qnominal, where Qnominal is the cfm chapters from the brochure.

Permit'southward run the calculation for the higher up referenced FX4 refrigerated air dryer and encounter if it can actually handle our 40cfm, G7-125 compressor.

For the formula I'll use these conditions based on the Texas gulf declension area: 100 F ambient, 120 F inlet air temperature, and 116 psi.

Qactual = 1 (ambience cistron) ten 0.58 (inlet temp factor) x ane.03 (inlet psi gene) ten 49 Qnominal

Qactual = 29.3 cfm for a 41 F dew point

What this equates to is water in your air lines fifty-fifty though you lot have a dryer installed. Let'due south work backward and go the correct dryer.

Qnominal = xl (compressor menses / Qactual needed) / one / .58 / 1.03

Qnominal = 67 cfm

This bumps united states to an FX5 dryer with a nominal capacity of 74 cfm for a 41 F dew point. You would have some excess capacity in cool weather just that's just office of the game.

Atlas Copco FX5 non-cycling refrigerated air dryer

This is a cursory wait at refrigerated air dryer sizing simply it's more than than enough for general shop air. No need to overcomplicate things.

If you have a big compressed air system with critical dew point requirements or need instrument grade air from a desiccant dryer, drop us a line for aid. If you have questions or need help with the to a higher place info for general shop air, feel free to drib u.s.a. a line.

Cheers,

Heath