/ Resources · Sizing

What size dryer do you need?

A dryer's nameplate SCFM is only good at 100 psi, 100 F air in, and a 100 F room. Put in your real conditions and see what size dryer it takes to keep up.

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Your air and your room

updates as you type

Dryer type

Refrigerated Desiccant

Refrigerated gets you about a 38 F dew point. That covers most shop and plant air. Need it drier, for outdoor lines in winter, paint, or instruments? Go desiccant.

Air flow to dry (SCFM) Use the compressor's full output, not the average. Pressure at the dryer inlet (psig) Use the lowest it runs at. Lower pressure carries more water. Air temperature going in (F) After the aftercooler, on the hottest day. Room temperature (F) Where the dryer sits, in summer.

Factors vary by maker. Every dryer brand publishes its own table, and they do not match. We use one maker's published tables so the math is traceable. Before you buy, check the table for the exact model.

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How the math works

1. Start from the rating point

Dryers are rated at 100 psi, 100 F air in, and a 100 F room. At those conditions every factor is 1.00 and the nameplate is the real number.

2. Look up each factor

Hotter air in or a hotter room drops the factor below 1. Higher pressure lifts it above 1. Between table rows we draw a straight line.

3. Divide

needed SCFM = your flow / (all factors multiplied). Then pick the first dryer whose nameplate is at or above that.

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The tables we use

factor = 1.00 at the rating point

Refrigerated

Inlet pressure (psig)	60	80	100	120	140	160	180	200
Factor	0.79	0.91	1.00	1.07	1.13	1.18	1.23	1.27

Inlet air (F)	90	100	110	120	130
Factor	1.11	1.00	0.80	0.65	0.53

Room (F)	80	90	100	110	115
Factor	1.10	1.07	1.00	0.83	0.70

Source: Beko Technologies, DRYPOINT RAc refrigerated dryer brochure, correction factors for operating pressure, inlet air temperature, and ambient air temperature. Beko says the factors are an estimate and to confirm sizing with them. No dew point factor: a refrigerated dryer is built for one dew point, about 38 F (ISO 8573-1 class 4).

Desiccant (heatless)

Inlet pressure (psig)	60	70	80	90	100	110	120	130	140	150
Factor	0.65	0.74	0.83	0.91	1.00	1.12	1.16	1.20	1.25	1.29

Inlet air (F)	90	95	100	105	110	115	120
Factor	1.07	1.04	1.00	0.86	0.73	0.64	0.55

Dew point	Factor
-13 F (-25 C)	1.10
-40 F (-40 C), ISO class 2, standard	1.00
-94 F (-70 C), ISO class 1, sold as the -100 F option	0.70

Source: pressure and inlet temperature from Beko Technologies, DRYPOINT XC heatless desiccant dryer brochure, correction factors. Beko lists no room temperature factor for heatless dryers, so we use 1.00. Dew point factors from a second maker, BERG Kompressoren DRYBERG AD desiccant dryer data (-25 C = 1.1, -40 C = 1.0, -70 C = 0.7). BERG publishes these for its AD150 to AD4000 line; its compact models use different factors. Both makers rate at -40.

Want us to check the size?

Send us the numbers. We'll match a dryer from the lines we carry, with the right pre-filter, after-filter, and drain, and confirm it against that maker's own table.

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