The Castair BGAC2K is the kit version of the BGAC2 belt guard aftercooler — it combines the 50 CFM aftercooler core with the mounting hardware and brackets needed to install it on the belt guard of a 15 HP reciprocating air compressor. If you want to do the installation yourself and need everything in one package, this is the right order. You get the core and the hardware; you do the mounting.
The difference between the BGAC2, BGAC2K, and BGAC2M comes down to how much work is done for you before it ships. The BGAC2 is the bare core — no mounting hardware. The BGAC2K is the core plus the mounting hardware. The BGAC2M is the core already assembled to the mounting panel, ready to bolt on. If you have a standard 15 HP belt-drive reciprocating compressor and a basic set of hand tools, the BGAC2K gives you everything you need without paying for factory pre-assembly.
What Is Included in the BGAC2K Kit
- Aftercooler core: 50 CFM belt guard aftercooler, 18 in L x 14-1/4 in W, 1 in NPT inlet and outlet connections
- Mounting hardware: Brackets and fasteners for installation on a standard compressor belt guard panel
- Everything needed for a complete belt guard aftercooler installation — minus the plumbing fittings and condensate drain, which depend on your specific site layout
Core Performance Specifications
- CFM Rating: 50 CFM — matched to 15 HP reciprocating compressors
- Rated Inlet Air Temperature: 250°F
- Maximum Operating Pressure: 250 PSIG
- Maximum Operating Temperature: 350°F
- Cooling Performance: Cools compressor discharge air to within 15°F above ambient temperature
- Moisture Reduction: Up to 65% reduction in water content
- Moisture physics: Approximately 50% of water content drops out for every 20°F reduction in air temperature. A typical 150–200°F temperature drop through the aftercooler 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 (aftercooler core; total kit weight may be slightly higher)
- Configuration: Kit — core plus mounting hardware, installer assembles and mounts
How Belt Guard Aftercoolers Work
- Air-cooled operation: The aftercooler core mounts in the path of the compressor flywheel fan''s airflow. The fan is driven by the compressor itself — no external blower needed. As the fan pulls air across the core, it removes heat from the compressed air passing through the internal passages.
- Discharge-point installation: The BGAC2K installs between the compressor cylinder head discharge port and the receiver tank inlet. Compressed air at 200–350°F enters the aftercooler and exits at close to ambient temperature before it ever reaches the tank.
- Condensation before the tank: Cooling the air before it enters the tank causes moisture to condense at the aftercooler outlet rather than inside the tank and downstream lines. This is where you want the condensation to happen — at a controlled drain point, not scattered throughout your distribution system.
- Pair with a moisture separator: For best results, install a moisture separator/trap at the aftercooler outlet. The separator catches the liquid that condenses out and channels it to a drain. An automatic float-type drain valve keeps the system hands-free.
Who Should Order the BGAC2K vs. BGAC2 or BGAC2M
- Order BGAC2K if: You have a standard 15 HP belt-drive reciprocating compressor and you want to do the installation yourself. You have basic tools and you want everything — core and hardware — in one shipment.
- Order BGAC2 (loose core) instead if: You have a non-standard mounting situation — custom enclosure, existing bracket you are reusing, or a position that does not match the standard belt guard panel mount. The bare core gives you maximum flexibility.
- Order BGAC2M instead if: You want the aftercooler pre-assembled to the mounting panel. The BGAC2M ships as a ready-to-bolt-on unit — no hardware assembly step for you.
- Order BGAC2x2M instead if: You have a duplex (twin-pump) compressor or need 100 CFM total capacity from two paired units.
Installation Notes
- Position the core in the fan airflow: The aftercooler must be in the direct path of the flywheel fan''s cooling air. Positioning it to the side or downstream of the main airflow will significantly reduce cooling performance.
- High-temperature inlet plumbing: The discharge side — from cylinder head to aftercooler inlet — must be plumbed with material rated for 250 PSIG and 350°F. High-temperature flexible hose or hard copper/steel pipe are appropriate. Standard rubber air hose is not rated for these temperatures.
- Outlet plumbing: The air leaving the aftercooler is near ambient temperature. Standard compressed air fittings and hose are suitable on the outlet side.
- Condensate drain: Install a drain at the lowest point after the aftercooler — ideally at a moisture separator outlet. An automatic float drain is the preferred solution for continuous operation. Manual drains work but require attention.
- Questions on fitment: If you are not certain this kit fits your specific compressor model, call 866-217-0063 before ordering. We can confirm compatibility.
Technical Specifications
- SKU: BGAC2K
- 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 (core)
- 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: Kit (core + mounting hardware)
Available Configurations — Full BGAC Series Lineup
Cast Air belt guard aftercoolers are available in four sizes to match different compressor horsepower ratings:
- 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 / BGAC2K — 50 CFM (this series): 18 in x 14-1/4 in core, 1 in NPT connections, 12 lbs. Fits 15 HP. Loose core (BGAC2), mounted assembly (BGAC2M), or kit (BGAC2K). Duplex mounted version available as 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.
Size your aftercooler to your compressor''s actual CFM output at working pressure — not just its horsepower rating. If your 15 HP compressor is rated for 50–55 CFM at 100 PSIG, the BGAC2 series is the right match.
When Does a Shop Need This vs. Stepping Up or Down
- BGAC2K is right for you if: You have a 15 HP reciprocating compressor, you are getting water problems downstream, and you want to do a proper belt guard aftercooler installation yourself with all hardware included.
- Step down to BGAC1 series if: Your compressor is 10 HP or smaller. The 35 CFM BGAC1 series is sized for those machines.
- Step up to BGAC3 series if: Your compressor is rated above 15 HP or if you are running your 15 HP machine at maximum capacity in a hot shop and want more cooling margin.
- Use BGAC2M instead if: You want a factory pre-assembled unit with no hardware assembly step — just bolt it on and plumb it in.
- Use BGAC2x2M instead if: You have a duplex compressor or need to cover two compressor discharge points simultaneously.
Why Buy From Air Compressor Factory Direct
- Specialist since 2016: Compressed air equipment is our specialty — compressors, aftercoolers, dryers, separators, and accessories. Not a general industrial catalog where compressed air is one of hundreds of product categories.
- Free shipping: All orders to the continental United States ship free.
- Free tech support: Call 866-217-0063. We can confirm the BGAC2K fits your compressor model, walk through the installation sequence, and help you plan condensate drain placement.
- Full manufacturer warranty: Cast Air factory warranty. No gray-market stock.
- Honest product guidance: If the BGAC2K is not the right configuration for your installation, we will tell you before the order ships.
Call 866-217-0063 for quick answers and help!
