Cast Air R15312HG30 — 15 HP 3-Phase Rotary Screw Air Compressor, 120-Gallon Horizontal Tank (230V or 460V)
The Cast Air R15312HG30 is the base model designation for the 15 horsepower 3-phase rotary screw compressor series with a 120-gallon horizontal tank. This unit is available in two voltage configurations: 230V 3-phase (model suffix -230) and 460V 3-phase (model suffix -460). At $11,112, you are making a serious capital investment in shop infrastructure — this is the compressor you buy when you intend to stop worrying about air supply for the next decade.
Before ordering, specify your voltage when you call or order. The physical unit and mechanical performance are the same. What differs is the motor winding, starter contactor, and electrical connections. Make sure your shop service matches the voltage you order — a 460V unit on a 230V service is not a configuration error you can correct with a quick part swap.
What You Get With 15 Horsepower of Rotary Screw Output
- Continuous duty operation: Rotary screw compressors are engineered to run 100% of the time at rated output without thermal overload or premature wear. This is not a piston compressor that needs rest cycles. If your shop runs two shifts, this unit can run both shifts.
- CFM output at 100 PSI: The 460V variant is rated at 58 CFM at 100 PSI. That output is sufficient to simultaneously run two HVLP spray guns, multiple impact wrenches, and air-powered lift controls without pressure drops during concurrent use.
- Quieter operation than piston alternatives: Rotary screw compression eliminates the reciprocating piston noise. Shops often notice an immediate drop in ambient noise level when switching from a piston compressor of equivalent output. That matters when you are making phone calls next to the compressor room.
- Lower maintenance complexity: Service intervals consist of oil changes, oil filter, air/oil separator element, and intake filter replacement. No piston rings, no cylinder honing, no valve plate replacement cycles.
Who Steps Up to 15HP
- Body shops running spray work and tools simultaneously: Paint prep, blocking, and body work all pull air at the same time in a busy collision center. A 10HP unit (approximately 35–42 CFM) can run out of margin when the booth is painting and the prep stall is active simultaneously. 15HP closes that gap.
- Fleet service facilities with multiple bays: Trucks, buses, and heavy equipment require higher-CFM tools — 3/4" and 1" impacts, air-powered lug removal, high-volume blow guns. If you have four or more bays working at the same time, 10HP compressors often can't keep up.
- Shops that have already maxed out their 10HP unit: The most reliable indicator that you need to step up: your existing compressor runs continuously and pressure still drops during peak tool use. That's the signal. A 15HP rotary screw with a 120-gallon tank addresses it directly.
- New facility construction: If you are building out a new shop and sizing the air system from scratch, 15HP is the appropriate anchor for a 4–6 bay facility with moderate-to-heavy tool density.
Voltage Selection: 230V vs. 460V
- 230V 3-phase (R15312HG30-230): Choose this if your shop has 230V 3-phase service and adding a 460V panel or transformer is not practical. Many shops already running 230V 3-phase equipment (lifts, welders, older CNC) will find the 230V version the simpler path to installation.
- 460V 3-phase (R15312HG30-460): At 460V, the amperage draw for the same 15HP output is roughly half what the 230V unit requires. That translates to smaller wire gauge for the supply run, smaller breaker, and less heat load on your panel. If your facility has 460V available, this is the preferred option for a compressor of this size.
- Electrical planning: Engage a licensed electrician before ordering. Supply wire sizing depends on your run length, local electrical code, and available panel capacity — not just the nameplate voltage and HP.
- Transformer option: If your shop has only one voltage available and it doesn't match the version you prefer, a step-up or step-down transformer is an option — but adds cost and complexity. It's generally simpler to match the unit to your existing service.
120-Gallon Horizontal Tank
- Storage volume: 120 gallons of system-pressure storage buffers against short demand spikes. Tools that briefly demand more CFM than the compressor's output draw down the tank pressure rather than stalling the motor.
- Horizontal configuration: The tank lies on its side rather than standing vertically. Plumbing taps along the tank length are accessible at waist or ground level. Condensate drains at the tank end, at the lowest point. If your compressor room has height restrictions or you prefer easy access to the supply and drain connections, horizontal is the practical choice.
- Stability: Lower center of gravity than a vertical tank of the same capacity. More stable in environments with floor traffic and industrial vibration.
Installation Requirements
- 3-phase power is required: This unit does not run on single-phase residential or light commercial service. Confirm 3-phase availability at your location before purchasing.
- Compressor room ventilation: Adequate airflow in the compressor room is required to prevent thermal shutdown. The unit generates heat during operation. Refer to the installation manual for minimum room volume and ventilation requirements.
- Air distribution piping: Size your distribution main appropriately for the CFM output. Undersized piping causes pressure drop between the tank and your tools even when the compressor is running correctly. For most installations at this CFM level, a 3/4" or 1" main is the starting point.
- Condensate and drying: A refrigerated air dryer downstream of the compressor is strongly recommended for spray painting and precision pneumatic tooling. Compressed air from any compressor carries moisture; a dryer removes it before it reaches your equipment.
Additional Specifications
Detailed specifications — full-load amps by voltage, exact CFM curves, discharge temperature, oil capacity, inlet and outlet port sizes, footprint dimensions, and weight — are available upon request. Contact us with your application details and we will provide the full technical data sheet.
Why Buy From OEM Diagnostic Tools?
- Specialist since 2016: We focus on professional shop equipment. We understand the difference between compressor classes and can walk you through voltage selection, installation planning, and the right accessories for your application.
- Free shipping: Ships free to commercial addresses in the continental US.
- Free tech support: Call 866-217-0063 before you order to confirm the right voltage and configuration. Call after installation if you have commissioning questions. We support what we sell.
- Full manufacturer warranty: Cast Air warranty applies. We manage the process if a claim is needed.
- Honest sizing guidance: If 15HP is more than your shop needs, we will tell you. If your application really requires 20HP, we will tell you that instead. We are not here to upsell — we are here to make sure you get the right unit.
Call 866-217-0063 for quick answers and help!
