Castair I15324HC3-S: 15HP 3-Phase Industrial Air Compressor — 120 Gallon Horizontal with Aftercooler
The Castair I15324HC3-S is a 15-horsepower, 3-phase, 120-gallon horizontal industrial air compressor with Castair's C3 cast iron pump and a factory-mounted belt guard aftercooler. The horizontal tank layout is the practical choice when overhead clearance is tight or when you need to position the compressor in a low-ceiling mechanical room, under a mezzanine, or along a wall where vertical height is a constraint.
Performance is identical to the vertical I15312VC3-S: 795 RPM pump speed, 61.7 CFM free air delivery, 50.2 CFM at 175 PSI, and 1,185 lbs. The difference is geometry — 69 x 24 x 62 inches versus 44 x 30 x 82 inches. The horizontal unit is longer but significantly shorter, which changes what installation options are available in your shop.
The -S designation means it ships with the BGAC2M belt guard mounted aftercooler — the same 50 CFM unit used on all 15HP Castair industrial models. This reduces discharge air temperature before it enters the tank, condensing moisture before it reaches your tools, airlines, or spray equipment.
Pump Design — C3 Cast Iron
Construction
- Pump designation: C3 — Two-stage, W3 cylinder configuration
- RPM: 795 — slow-speed operation reduces heat and extends service life
- All cast iron: Cylinders, heads, valve plates, crankcase — no aluminum components in the compression system
- Tapered roller bearings at both ends of the crankshaft
- Precision steel connecting rods with automotive-type rod insert bearings at crankshaft and wrist pin
- Disc and spring valves — field-replaceable without specialized tooling
- 4-ring pistons for efficiency and reduced oil carry-over
- Centrifugal unloader — loadless start-up protects the motor every cycle
- Oil capacity: 1 gallon
Tank and Structure
- Tank capacity: 120 gallons, horizontal orientation
- Tank finish: Powder-coated ASME-rated steel
- Frame: Channel steel saddle on horizontal models
- Safety valve: ASME-rated, factory installed
- Belt guard: Totally enclosed metal with aftercooler mounting
- Discharge lines: Copper tubing or stainless braided flex line
Motor
- Horsepower: 15HP
- Phase: 3-phase (requires 3-phase service)
- Motor speed: 1725 RPM industrial
- Service factor: 15% minimum
- Max working pressure: 175 PSI
Performance Specifications
- Motor output: 15 HP
- Electrical: 3-phase
- Tank capacity: 120 gallons, horizontal
- Pump RPM: 795
- Free air delivery (0 PSI): 61.7 CFM
- Delivery at 175 PSI: 50.2 CFM
- Max pressure: 175 PSI
- Dimensions (LxWxH): 69 x 24 x 62 inches
- Weight: 1,185 lbs
- Aftercooler: BGAC2M included (belt guard mounted, 50 CFM)
Horizontal vs. Vertical — Choosing the Right Tank Orientation
The choice between horizontal and vertical tank comes down to your installation space:
- Horizontal (this unit — I15324HC3-S): 69 x 24 x 62 inches — lower profile, better for low-ceiling spaces, mechanical rooms, or under mezzanines. Footprint is longer but narrower in depth.
- Vertical (I15312VC3-S): 44 x 30 x 82 inches — smaller floor footprint, taller. Better when ceiling height allows and floor space is the constraint.
Both deliver identical performance: same pump, same motor, same CFM. Pick the orientation that fits your installation space. If you have 10+ foot ceilings and need to minimize floor footprint, go vertical. If ceiling height is limited, the horizontal is the right call.
What's in the Box
- Castair I15324HC3-S compressor — fully assembled
- BGAC2M belt guard mounted aftercooler (50 CFM)
- ASME safety valve (factory installed)
- Pressure switch with unloader
- Totally enclosed metal belt guard
- Copper discharge and unloader tubing (or stainless braided flex line)
- Owner's documentation
Magnetic motor starter is not included unless specifically ordered. 3-phase electrical service and proper motor starter are required for installation.
Available Configurations — 15HP Horizontal Industrial Series
- I15312HC2-S: 15HP, 3-phase, 120gal Horizontal, C2 pump, 898 RPM, 45.3 CFM @ 175 PSI, 69x24x50, 980 lbs — lighter with slightly lower CFM
- I15324HC3-S (this unit): 15HP, 3-phase, 120gal Horizontal, C3 pump, 795 RPM, 50.2 CFM @ 175 PSI, 69x24x62, 1,185 lbs — more CFM, heavier C3 pump
When Does a Shop Need This?
- You need maximum CFM from a 15HP horizontal unit — 50.2 CFM at 175 PSI supports 3-5 technician stations running impact guns, air ratchets, and similar tools
- Your shop has low ceiling height or overhead obstructions that make a vertical compressor impractical
- You have 3-phase electrical service and need a compressor matched to that power supply
- Aftercooler-treated air is important for your application (painting, sandblasting, precision pneumatics)
Why Buy From Air Compressor Factory Direct?
We have specialized in industrial air compressors and shop equipment since 2016. Our staff understands the difference between a C2 and C3 pump, can walk you through your electrical requirements, and will help you choose between horizontal and vertical configurations based on your actual shop layout — not just what happens to be in stock.
- Free shipping to commercial addresses in the lower 48 states
- Free tech support at 866-217-0063 before and after your purchase
- Full Castair manufacturer warranty
- Honest buying guidance — we size compressors to real shop needs
- Authorized dealer with direct Castair support access
Call 866-217-0063 for quick answers and help!
