Castair BGAC2M

The Castair BGAC2M is a 50 CFM belt guard aftercooler built to mount directly on the belt guard of a 15 HP reciprocating air compressor. Unlike the loose BGAC2 core, the BGAC2M comes as a pre-mounted assembly — it bolts onto the compressor belt guard panel and sits in the direct airflow from the flywheel fan. Plumb the compressor discharge to the 1 in NPT inlet, run the outlet to your receiver, and you have an aftercooler system that requires no custom fabrication or bracket work.

The purpose is straightforward: compressed air leaving a reciprocating compressor cylinder can be 200–350°F. At those temperatures, virtually all the water vapor stays airborne and travels downstream into your tank, lines, and tools. The BGAC2M drops that temperature to within 15°F of ambient, causing the water vapor to condense and drop out of the air stream before it reaches your equipment. The result is up to 65% less moisture in your compressed air system.

Core Performance Specifications

• CFM Rating: 50 CFM — sized for 15 HP reciprocating compressors
• Rated Inlet Air Temperature: 250°F (performance figures based on this inlet condition)
• Maximum Operating Pressure: 250 PSIG
• Maximum Operating Temperature: 350°F
• Cooling Performance: Cools discharge air to within 15°F above ambient temperature
• Moisture Reduction: Up to 65% reduction in water content
• Moisture physics: Water content in compressed air decreases by approximately 50% for every 20°F drop in temperature. A 150–200°F temperature drop delivers the 65% moisture reduction figure.

Physical Dimensions and Connections

• Aftercooler 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: Mounted — pre-assembled to a belt guard mounting panel for direct installation on the compressor

Why the Mounted Configuration

• Purpose-built fitment: The BGAC2M is designed to attach directly to the belt guard of a standard 15 HP reciprocating compressor. The mounting panel positions the aftercooler core squarely in the flywheel fan''s cooling airflow — which is exactly where it needs to be for maximum heat transfer.
• No bracket fabrication: The loose BGAC2 core requires you to fabricate or source a mount and position it correctly relative to the fan. The BGAC2M eliminates that step. Bolt it on, plumb it in.
• Airflow optimization: Factory positioning means the core is in the right place relative to the fan blades. A poorly positioned aftercooler — even with the same core — will underperform because it is not getting adequate airflow across the fins.
• Clean installation: Integrated mounting keeps the aftercooler compact and close to the compressor frame, reducing the length of high-temperature discharge piping required.

How Belt Guard Aftercoolers Work

• Air-cooled operation: The BGAC2M uses the compressor''s own flywheel fan to move cooling air across the aftercooler core. No external blower or utility power connection required beyond what the compressor already runs.
• Discharge-point cooling: Hot compressed air from the cylinder head flows into the aftercooler inlet immediately after leaving the compressor. Cooling happens before the air enters the receiver tank — so condensation happens at the aftercooler, not inside your tank and distribution lines.
• Condensate management: Pair the BGAC2M with a moisture separator at the outlet and an automatic or manual condensate drain. The aftercooler drops the temperature and causes condensation; the separator and drain remove that liquid from the system.

Installation Notes

• Bolt-on to belt guard: The BGAC2M mounts to the existing belt guard panel of the compressor. Confirm your compressor frame and belt guard dimensions are compatible before ordering — call us at 866-217-0063 if you need help verifying fitment.
• Plumbing: Use high-temperature hose or hard pipe rated for 250 PSIG and 350°F on the discharge side between the cylinder head outlet and the BGAC2M inlet. The outlet side runs at much lower temperatures and standard compressed air fittings are appropriate.
• Condensate drain: Install a drain valve at the lowest point in the system after the aftercooler. An automatic float-type drain is preferred for continuous operation so you are not manually draining on a schedule.
• If you need a loose core for a custom install: Order the BGAC2 instead. If you need the core plus mounting hardware but want to do the installation yourself, order the BGAC2K kit.

Technical Specifications

• SKU: BGAC2M
• 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: Mounted (pre-assembled to belt guard mounting panel)

Available Configurations — Full BGAC Series Lineup

Cast Air belt guard aftercoolers are available in four sizes. Match the aftercooler to your compressor horsepower:

• 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.
• 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.
• BGAC4 / BGAC4M — 100 CFM: 23 in x 26-1/2 in core, 1 in NPT connections, 25 lbs. For larger systems.

Do not undersize. A 35 CFM BGAC1 on a 15 HP compressor will not cool effectively — the air velocity through the core is too high for adequate heat transfer. Match CFM rating to your compressor''s actual output at your working pressure.

When Does a Shop Need This vs. Stepping Up or Down

• The BGAC2M is correct for you if: You have a 15 HP reciprocating compressor and want a factory-mounted aftercooler that installs directly on the belt guard with no custom fabrication. Moisture problems downstream — water in lines, tool failures, rusty tank interiors — are the trigger to add an aftercooler.
• Choose BGAC2 (loose) instead if: You are doing a custom installation, replacing a core in an existing housing, or your belt guard geometry does not match the standard BGAC2M panel.
• Choose BGAC2K instead if: You want the aftercooler core plus mounting hardware/brackets but plan to do the final installation yourself.
• Choose BGAC2x2M instead if: You have a duplex (twin-pump) compressor setup and need aftercooler coverage on both discharge lines simultaneously, or if your total system needs 100 CFM of aftercooling.
• Step down to BGAC1M if: Your compressor is 10 HP or smaller. Using a 50 CFM core on a smaller machine is not harmful but wastes money on unnecessary core area.
• Step up to BGAC3M if: Your compressor is rated above 15 HP, or if you are running a 15 HP machine in an exceptionally hot environment where you want additional cooling margin.

Why Buy From Air Compressor Factory Direct

• Specialist since 2016: Compressed air equipment — compressors, aftercoolers, dryers, separators, accessories — is our focus. Not a general industrial catalog.
• Free shipping: Orders to the continental United States ship free.
• Free tech support: Call 866-217-0063. We can verify fitment to your specific compressor model, confirm connection sizing, and help you plan the full installation including drain and separator placement.
• Full manufacturer warranty: Cast Air factory warranty on all BGAC series aftercoolers.
• Honest sizing advice: If the BGAC2M is wrong for your application, we will tell you before you buy it.

Call 866-217-0063 for quick answers and help!