The Castair FSAC35 is a free-standing air-cooled aftercooler rated for 35 CFM. It connects to the compressor discharge line and cools hot compressed air — which can exit a pump at up to 350 degrees F — back down to within 15 degrees of ambient temperature before it reaches your air system. That temperature drop removes up to 65% of the water that compression vaporizes and suspends in the air stream, reducing moisture in your tools, spray guns, and air lines significantly.
Why an Aftercooler Matters
Here is the physics: compression heats air and keeps moisture suspended as vapor. When that air cools in your distribution lines and drops below the dew point, that vapor condenses into liquid water — inside your piping, your tools, and your spray equipment. An aftercooler forces that condensation to happen in one controlled location (the aftercooler and its drain) rather than randomly throughout your air system.
Castair's spec: every 20-degree temperature reduction removes 50% of suspended moisture. The FSAC35 brings discharge air to within 15 degrees of ambient, which typically produces up to 65% total moisture reduction. For shops experiencing rust in air lines, water in spray guns, or tool corrosion, an aftercooler is the correct fix — not more filters downstream.
Key Specifications
- Part Number: FSAC35
- Style: Free standing
- Rated Capacity: 35 CFM
- Inlet/Outlet Connection: 3/4" NPT
- Dimensions (L x W x H): 21" x 12" x 27"
- Weight: 30 lbs
- Maximum Operating Pressure: 250 PSIG
- Maximum Operating Temperature: 350 degrees F inlet
- Performance Basis: 250-degree F inlet air temperature
- Electrical: 115V, 1-phase, 60 Hz
- Mounting: Floor or suspended; horizontal or vertical airflow
Free Standing vs. Belt Guard Style at 35 CFM
Castair makes aftercoolers in two mounting styles for the 35 CFM range:
- BGAC1 — Belt guard style, 35 CFM, 3/4" connections, 18" x 10.5", 8 lbs. Mounts on or near the compressor. Available loose (BGAC1) or pre-mounted (BGAC1M).
- FSAC35 — Free standing, 35 CFM, 3/4" NPT, 21x12x27", 30 lbs. Installs independently of the compressor.
If your compressor is accessible and the belt guard area works for plumbing, the BGAC1 is simpler and lighter. The FSAC35 works for installations where the compressor is in an enclosure, a separate room, or where remote mounting is needed.
Free Standing Aftercooler Lineup
- FSAC35 — 35 CFM, 3/4" NPT, 21x12x27", 30 lbs (this model)
- FSAC50 — 50 CFM, 1" NPT, 21x12x31", 40 lbs
- FSAC75 — 75 CFM, 1" NPT, 27x15x36", 70 lbs
- FSAC100 — 100 CFM, 1-1/4" NPT, 26x16x42", 80 lbs
- AC120 — 120 CFM, 1-1/2" NPT, 43.5x14.75x46.5", 140 lbs
- AC150 — 150 CFM, 1-1/2" NPT, 43.5x14.75x46.5", 145 lbs
- AC240 — 240 CFM, 2" NPT, 200 lbs
- AC300 — 300 CFM, 2" NPT, 300 lbs
Sizing and Buying Guidance
Size the aftercooler to your compressor's actual CFM output at the discharge port — not motor HP and not free-air-delivery at 0 PSI.
- FSAC35 is correct for compressors delivering up to 35 CFM
- Step up to FSAC50 if your compressor delivers 35-50 CFM — never undersize an aftercooler
- Consider BGAC1 instead if the compressor is accessible and you can mount to the belt guard area — same 35 CFM rating, much lighter at 8 lbs
Optional Accessories
- Filter with auto drain — Available on all free-standing models; drains condensate automatically
- Temperature control valve #86816 — Prevents overcooling in cold ambient conditions
Why Buy From OEM Diagnostic Tools?
OEM Diagnostic Tools has supplied professional shop equipment and components since 2016. We stock Castair aftercoolers so shops can solve moisture problems with properly sized equipment. Free shipping on qualifying orders, free tech support at 866-217-0063, and full manufacturer warranty. Call us if you need help sizing the correct aftercooler for your compressor's CFM output.
Call 866-217-0063 for quick answers and help!
