The Castair BGAC4 is the top-tier unit in the BGAC belt guard aftercooler series — rated at 100 CFM and built for high-output reciprocating compressors that exceed the 75 CFM capacity of the BGAC3. If your system is running a large-frame two-stage compressor with significant continuous airflow output and the BGAC3 is undersized, the BGAC4 is the correctly specified unit. It is the largest aftercooler in the BGAC series and handles the full discharge output of the most demanding reciprocating compressor installations.
This is the loose unit configuration — sold standalone without compressor-specific mounting hardware. For the pre-configured compressor-mount version, that is the BGAC4M.
What the BGAC4 Does at 100 CFM
High-output reciprocating compressors discharge air at temperatures that can exceed 250°F at the pump head. At that temperature, water stays in vapor form and travels through the system unchecked — corroding the tank interior, saturating inline filters, and damaging downstream tools, valves, and spray equipment. The BGAC4 eliminates that problem at the source.
Mounted within the belt guard assembly, the BGAC4 intercepts hot discharge air before it reaches the tank. Ambient airflow from the compressor flywheel or a dedicated fan passes over the large finned core and drops the air temperature rapidly. Moisture condenses, collects at the aftercooler, and drains away. The result is discharge air cooled to within 15°F of ambient temperature with up to 65% of moisture removed — regardless of how hard the compressor is running.
- Temperature reduction: Cools compressed air to within 15°F above ambient temperature at rated flow
- Moisture removal: Eliminates up to 65% of water content before it reaches the tank and distribution system
- 100 CFM capacity: Handles the discharge output of large-frame reciprocating compressors — the largest unit in the BGAC series
- No cooling water connection: Air-to-air design — connections limited to the 1" NPT air inlet and outlet
- Tank and downstream protection: Keeping moisture out of the tank extends service life and prevents water damage to pneumatic equipment
Design and Construction
- Belt guard integration: Mounts within the compressor belt guard assembly — no external mounting brackets or standalone installation required
- 1" NPT connections: Standard 1" NPT inlet and outlet — matches the discharge plumbing of high-output reciprocating compressors
- 250 PSIG maximum operating pressure: Rated for the full output pressure range of large industrial reciprocating compressors
- 350°F maximum operating temperature: Engineered for the actual discharge temperatures produced by large-frame pump heads
- Performance tested at 250°F inlet: All ratings verified at real compressor discharge conditions — not ambient air temperature
- Loose unit configuration: Ships as a standalone unit — for field installation or replacement without requiring compressor-specific mounting hardware
- Larger core than BGAC3: At 23" x 26-1/2" and 25 lbs, the BGAC4 has a larger cooling surface than the BGAC3, enabling the higher 100 CFM throughput
Technical Specifications
- SKU: BGAC4
- CFM Rating: 100 CFM
- Dimensions: 23" L x 26-1/2" W
- Weight: 25 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)
- Position in Series: Top tier — largest unit in the BGAC lineup
- Manufacturer: Cast Air (Castair)
Available Configurations — Full BGAC Series Lineup
Castair produces the BGAC series in four sizes. Each size is available as a loose unit and a compressor-mounted version (M suffix). Match the aftercooler CFM rating to your compressor's actual output, not just the nameplate HP.
- 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
- BGAC4 / BGAC4M: 100 CFM — 23" x 26-1/2", 1" NPT connections, 25 lbs — for high-output systems above the BGAC3 range (this unit)
If your compressor is in the 20-25 HP range producing 75 CFM or less, the BGAC3 may be the more appropriately sized unit. The BGAC4 is the correct choice when the compressor output actually exceeds 75 CFM at operating conditions. Call 866-217-0063 with your compressor model and we can confirm which unit fits.
When Does a Shop Need the BGAC4 vs. Stepping Down to the BGAC3?
The BGAC4 is the right choice in these situations:
- High-output two-stage compressors: Large-frame industrial two-stage units producing more than 75 CFM at operating pressure — the BGAC3 is undersized for these applications
- Continuous-duty high-demand systems: Shops or facilities where the compressor runs nearly continuously — a larger aftercooler handles the sustained thermal load better
- Replacement for an existing BGAC4: Direct replacement for a failed or damaged BGAC4 in an existing installation
- Future-proofing large installs: If the compressor is close to the BGAC3 limit and the shop anticipates adding equipment or increasing air demand
Do not step up to the BGAC4 if your compressor is genuinely within the BGAC3 range — a correctly sized unit performs better than an oversized one. If you are unsure, call us with the compressor model, HP, and rated CFM output and we will confirm the right unit before you order.
Why Buy From Air Compressor Factory Direct?
We have been specializing in air compressor parts, components, and accessories since 2016. We carry the full Castair BGAC series and can confirm which size and configuration is correct for your specific compressor and installation. You talk to someone who knows compressors — not a general customer service representative reading from a screen.
- Free shipping on qualifying orders
- Free technical support at 866-217-0063 — we help you confirm the right aftercooler size before you order
- Full manufacturer warranty on all Castair products
- Honest sizing guidance — if the BGAC3 is the better fit for your compressor, we will tell you that instead of upselling you to the BGAC4
Call 866-217-0063 for quick answers and help!
