The Castair BGAC3 is a belt guard aftercooler rated at 75 CFM, built for reciprocating compressors in the 20 HP and larger class. If your shop is running a larger two-stage compressor and you are dealing with moisture in your air lines, rusting inside the tank, or water carryover damaging downstream equipment, the BGAC3 is the correctly sized unit for that installation. It installs in the compressor discharge line immediately after the pump head, drops the air temperature, and condenses moisture before it ever reaches the tank.
This is the loose unit configuration — sold standalone without compressor mounting hardware. If you need it pre-configured for direct compressor base mounting, that is the BGAC3M.
What the BGAC3 Does and Why It Matters
A reciprocating compressor discharges air at high temperature — often 250°F or above at the pump head. At that temperature, water stays in vapor form and travels right through the system: into the tank, through the lines, and into your air tools and equipment. An aftercooler cuts that off at the source.
The BGAC3 routes the hot discharge air through a finned core. Ambient shop airflow — typically from the compressor flywheel or a dedicated fan — passes over that core and drops the air temperature to within 15°F above ambient. At that temperature, water vapor condenses into liquid, drops out of the airstream, and drains away. What reaches your tank and distribution system is cooler and significantly drier air.
- Temperature reduction: Cools compressed air to within 15°F above ambient temperature
- Moisture reduction: Removes up to 65% of water content from the compressed air stream
- No cooling water required: Air-to-air design uses ambient shop airflow — no plumbing connections beyond the air inlet and outlet
- Tank protection: Keeping moisture out of the tank significantly extends tank service life and reduces corrosion risk
- Downstream equipment protection: Cooler, drier air means less wear on pneumatic tools, cylinders, valves, and spray equipment
Design and Construction
- Belt guard integration: Designed to mount within the compressor belt guard assembly — keeps the installation compact and protects the cooler core from shop debris
- 1" NPT connections: Standard 1" NPT inlet and outlet — straightforward connection to compressor discharge and tank inlet
- High-pressure rated: Maximum operating pressure of 250 PSIG — handles the output of industrial reciprocating compressors without issue
- High-temperature rated: Maximum operating temperature of 350°F — engineered for the full discharge temperature range of larger reciprocating pumps
- Performance spec: All ratings based on 250°F inlet air temperature — tested under real compressor discharge conditions, not ambient
- Loose unit: Ships as a standalone unit without compressor-specific mounting hardware — for field installation or replacement applications
Technical Specifications
- SKU: BGAC3
- CFM Rating: 75 CFM
- Dimensions: 24" L x 20-1/2" W
- Weight: 20 lbs
- Inlet Connection: 1" NPT
- Outlet Connection: 1" NPT
- Maximum Operating Pressure: 250 PSIG
- Maximum Operating Temperature: 350°F
- Outlet Temperature: Within 15°F of ambient
- Moisture Reduction: Up to 65%
- Performance Basis: 250°F inlet air temperature
- Configuration: Loose unit (standalone)
- Compressor Fit: 20 HP and larger reciprocating compressors
- Manufacturer: Cast Air (Castair)
Available Configurations — BGAC Series Aftercooler Lineup
Castair makes the BGAC series in four sizes, each matched to a different compressor output range. Both a loose unit and a compressor-mounted version are available for each size.
- BGAC1 / BGAC1M: 35 CFM — 18" x 10-1/2", 3/4" NPT connections, 8 lbs — fits 5, 7, and 10 HP compressors
- BGAC2 / BGAC2M: 50 CFM — 18" x 14-1/4", 1" NPT connections, 12 lbs — fits 15 HP compressors
- BGAC3 / BGAC3M: 75 CFM — 24" x 20-1/2", 1" NPT connections, 20 lbs — fits 20 HP and larger compressors (this unit)
- BGAC4 / BGAC4M: 100 CFM — 23" x 26-1/2", 1" NPT connections, 25 lbs — for high-output systems above the BGAC3 range
The loose unit (BGAC3) is for field installations and replacements. The mounted unit (BGAC3M) ships pre-configured for direct compressor frame mounting. If you are not sure which to order, call 866-217-0063 with your compressor model and HP rating.
When Does a Shop Need the BGAC3 vs. Stepping Up or Down?
The BGAC3 is the right size when your compressor is rated at 20 HP or above and produces in the range of 75 CFM or less. If your compressor is in the 15 HP class, the BGAC2 at 50 CFM is the correct fit. If you are running a particularly high-output system — large-frame two-stage units, continuous-duty industrial compressors — and your discharge CFM exceeds 75, the BGAC4 at 100 CFM is the next step up.
Do not undersize the aftercooler relative to the compressor output. An undersized unit cannot cool the full airflow adequately, which means elevated outlet temperatures and reduced moisture separation. Match the aftercooler CFM rating to what the compressor actually produces at operating conditions, not just the nameplate HP.
If you are unsure whether the BGAC3 fits your specific compressor or if the BGAC4 is a better match, call us. We can look up your compressor model and confirm the correct aftercooler size before you order.
Why Buy From Air Compressor Factory Direct?
We have been specializing in air compressor parts, components, and accessories since 2016. Castair products are part of our regular inventory, and we carry the full BGAC series. When you call, you talk to someone who knows compressor configurations — not a general customer service line.
- Free shipping on qualifying orders
- Free technical support at 866-217-0063 — we help you confirm fitment before you order
- Full manufacturer warranty on all Castair products
- Honest sizing guidance — if the BGAC2 is the right unit for your compressor, we will tell you that instead of selling you a larger unit
Call 866-217-0063 for quick answers and help!
