8 inputs determine the right air dryer.

A distributor-facing pre-quote checklist. If the customer answers most of these at the first call, the second call is the quote.

1. 01
   What dew point does the end-use actually need at the use point?

   Spec sheets sometimes overshoot. Bottling and packaging are happy at +38°F. Painting, laser optics, electronics, and pharma typically need ‑40°F or drier. Outdoor or freezer-line distribution defaults to ‑40°F to avoid in-line condensation.
2. 02
   What's the dryer flow rate (SCFM) and the inlet pressure (PSIG)?

   Dryer plates rate at 100 PSIG, 100°F inlet. Higher inlet temp derates capacity sharply — every 18°F over rating cuts capacity roughly in half. Get the actual inlet condition, not the compressor's discharge plate.
3. 03
   Indoor or outdoor install? What's the ambient temperature range at the install location?

   Refrigerated dryers struggle below 50°F ambient and need shelter from direct sun. Desiccant towers tolerate a wider range. Outdoor exposure → NEMA 4 enclosure callout. If the answer is "in an unconditioned shed in Minnesota," the conversation changes.
4. 04
   Is the dryer's footprint in a hazardous-classified area?

   Class I Div 2, ATEX Zone 1/2, IECEx — any of these flip the entire spec to explosion-proof construction. Confirm before quoting; substituting an EP unit at order time is a 6-8 week lead-time event, not a stocking item.
5. 05
   How much purge air can the system afford?

   Heatless desiccant uses ~15% of dried capacity as purge. If the compressor was sized to flow, that's a ~15% capacity hit. If purge is a problem → heated or heated-blower desiccant cuts it to 4–7% but adds capex and an electrical heater. Refrigerated has zero purge.
6. 06
   Cleanliness class — is this air going somewhere with an ISO 8573-1 requirement?

   Pharmaceutical, food contact, medical breathing, semiconductor — these jobs come with an ISO class spec for particulates, water, and oil. The dryer hits the water class; filtration before and after hits particulate and oil. If they cite a class, write it on the quote.
7. 07
   Continuous duty or intermittent? Shift-only or 24/7?

   Refrigerated cycling and digital-scroll designs save energy on intermittent loads. Continuous heavy-duty plant air leans non-cycling. Desiccant always favors continuous duty — the regen cycle prefers steady flow.
8. 08
   Is there existing pre-filtration upstream of the dryer location?

   Desiccant media gets ruined by oil carryover, fast. A coalescing filter ahead of every desiccant install is non-negotiable. If the line doesn't have one, the dryer quote needs to include it or the dryer warranty doesn't survive the first quarter.