The Castair BGAC2 is a 50 CFM belt guard aftercooler built for 15 HP reciprocating air compressors. This is the loose (unmounted) version — you get the aftercooler core itself, ready to be installed however your setup requires. It cools compressor discharge air from as high as 350°F down to within 15°F of ambient temperature, which means dramatically less water vapor making it past your air dryer and into your lines, tools, and equipment.
If you are dealing with water in your compressed air system — rusty lines, water shooting from blow guns, air tools failing early, paint jobs ruined by moisture — an aftercooler installed at the compressor discharge is the right first step. Desiccant dryers and refrigerated dryers both work better when they are not fighting 200°F+ air. The BGAC2 does the heavy cooling so your downstream equipment does not have to.
Core Performance Specifications
- CFM Rating: 50 CFM — matched to 15 HP reciprocating compressors
- Inlet Air Temperature: Performance rated at 250°F inlet air temperature
- Maximum Operating Pressure: 250 PSIG
- Maximum Operating Temperature: 350°F
- Cooling Performance: Cools discharge air to within 15°F above ambient temperature
- Moisture Reduction: Reduces water content in the air stream by up to 65%
- Physics behind the numbers: Water content drops approximately 50% for every 20°F reduction in air temperature — the BGAC2 typically delivers a 150–200°F temperature drop, which is where the 65% figure comes from
Physical Dimensions and Connections
- Core Size: 18 in L x 14-1/4 in W
- Inlet Connection: 1 in NPT
- Outlet Connection: 1 in NPT
- Weight: 12 lbs
- Configuration: Loose unit — not pre-mounted, not a kit. Just the aftercooler core with connections ready for installation.
How Belt Guard Aftercoolers Work
- Air-cooled design: The aftercooler core is positioned in the airflow generated by the compressor flywheel fan. No separate cooling fan motor required — the compressor''s own rotation drives cooling air across the core.
- Discharge-point cooling: Hot compressed air exits the compressor cylinder head and passes through the aftercooler before entering the receiver tank or distribution system. Cooling happens immediately, before water vapor has a chance to condense inside your tanks and lines.
- Moisture separator pairing: For maximum water removal, pair the BGAC2 with a moisture separator/trap at the aftercooler outlet. The aftercooler drops the temperature; the separator catches the condensate that drops out of solution.
- Condensate drain: Install a manual or automatic drain at the lowest point after the aftercooler. Without a drain, the moisture you collect just accumulates.
What This Unit Is (and Is Not)
- Loose unit: The BGAC2 is the aftercooler core itself. It is not pre-mounted to a belt guard panel and does not include a mounting bracket kit. You mount and plumb it according to your specific compressor layout.
- Flexibility: The loose configuration is appropriate when you are integrating into a custom enclosure, replacing an existing aftercooler, or mounting in a non-standard position.
- Not a dryer replacement: An aftercooler removes a large percentage of moisture, but not all. For applications requiring very dry air (spray painting, air bearing equipment, certain pneumatic controls), follow the aftercooler with a refrigerated or desiccant dryer.
Installation Notes
- Mounting position: Position the core in the path of the compressor flywheel fan''s airflow for best cooling efficiency.
- Plumbing: Use 1 in NPT fittings and high-temperature hose or hard pipe rated for 250 PSIG and 350°F between the compressor discharge and aftercooler inlet.
- Drain placement: Install a condensate drain at the aftercooler outlet or in the first low point of the distribution system downstream.
- If you need mounting hardware: Order the BGAC2K kit version, which includes brackets and hardware for belt guard mounting. If you need a pre-mounted assembly ready to bolt onto your compressor, order the BGAC2M.
Technical Specifications
- SKU: BGAC2
- Manufacturer: Cast Air (Castair)
- CFM Capacity: 50 CFM
- Core Dimensions: 18 in L x 14-1/4 in W
- Inlet Connection: 1 in NPT
- Outlet Connection: 1 in NPT
- Weight: 12 lbs
- Maximum Pressure: 250 PSIG
- Maximum Temperature: 350°F
- Rated Inlet Temperature: 250°F
- Cooling to: Within 15°F of ambient temperature
- Moisture Reduction: Up to 65%
- Compressor Match: 15 HP reciprocating
- Configuration: Loose (unmounted)
- Price: $464.31
Available Configurations — Full BGAC Series Lineup
Cast Air makes belt guard aftercoolers in four sizes. Match the aftercooler to your compressor''s horsepower and CFM output:
- BGAC1 / BGAC1M — 35 CFM: 18 in x 10-1/2 in core, 3/4 in NPT connections, 8 lbs. Fits 5, 7, and 10 HP compressors. Smaller core, smaller connections — do not use on a 15 HP machine.
- BGAC2 / BGAC2M — 50 CFM (this unit): 18 in x 14-1/4 in core, 1 in NPT connections, 12 lbs. Fits 15 HP. Available loose (BGAC2), mounted (BGAC2M), kit (BGAC2K), or duplex (BGAC2x2M).
- BGAC3 / BGAC3M — 75 CFM: 24 in x 20-1/2 in core, 1 in NPT connections, 20 lbs. Fits 20+ HP compressors. Significantly larger core surface area for higher flow rates.
- BGAC4 / BGAC4M — 100 CFM: 23 in x 26-1/2 in core, 1 in NPT connections, 25 lbs. For larger systems requiring higher throughput.
Undersizing an aftercooler means the air does not spend enough time in the core to cool properly. Oversizing is not harmful but wastes money. Match CFM to your compressor''s rated output at the working pressure you run.
When Does a Shop Need This vs. Stepping Up or Down
- You need the BGAC2 if: You have a 15 HP reciprocating compressor and are seeing moisture problems downstream — water in lines, tools failing from rust, water in spray gun air, condensate in receiver tanks.
- Step down to BGAC1 if: Your compressor is 10 HP or smaller. The 35 CFM BGAC1 is sized for that output range and is less expensive.
- Step up to BGAC3 if: Your compressor is 20 HP or larger, or if you are running 15 HP hard in a hot environment and want more core surface area for better cooling margin.
- Choose BGAC2M over BGAC2 if: You want a factory-mounted assembly ready to bolt onto the belt guard panel of your compressor — no custom fabrication required.
- Choose BGAC2K over BGAC2 if: You want the loose aftercooler core plus the mounting hardware/brackets to install it on a belt guard yourself.
- Choose BGAC2x2M if: You have a duplex (twin-pump) compressor and need aftercooler coverage on both pump discharge lines, or if you need 100 CFM total aftercooling capacity from a paired setup.
Why Buy From Air Compressor Factory Direct
- Specialist since 2016: We focus on compressed air equipment — compressors, aftercoolers, dryers, separators, and accessories. Not a general industrial distributor where air equipment is a footnote.
- Free shipping: No freight surprises on orders to the continental United States.
- Free tech support: Call 866-217-0063 and talk to someone who knows these products. We can help you confirm the right aftercooler for your specific compressor model and application.
- Full manufacturer warranty: Cast Air aftercoolers carry the full factory warranty. No gray-market or diverted stock.
- Honest sizing guidance: If the BGAC2 is not the right fit for your system, we will tell you before you order — not after.
Call 866-217-0063 for quick answers and help!
