Castair 5HP 3-Phase Rotary Screw Air Compressor 80 Gallon Horizontal 460V — R538HP75-460
The Castair R538HP75-460 is a 5-horsepower, 3-phase, 460V, 80-gallon horizontal rotary screw air compressor delivering 20 CFM at 100 PSI. It weighs 470 pounds and measures 64×32×44 inches (L×W×H). Three-phase power means smoother motor starts, lower amperage per leg, and simpler motor construction than single-phase equivalents — if your shop has 3-phase service, use it. This unit is built around the P75 air end and is Castair's production-grade solution for 1-3 bay shops needing 100% duty cycle compressed air on 3-phase power.
P75 air end — maintenance kit MKP75 applies (covers 5-15HP with P75 element). If your facility runs 230V 3-phase, order the 230V variant instead.
3-Phase vs. Single-Phase at 5HP — Why It Matters
- Lower amperage per leg: A 5HP 3-phase motor distributes load across three legs. At 230V, expect approximately 13-15 amps per leg versus 25-30 amps for a single-phase 5HP motor. Smaller wire, smaller breaker, less heat in the circuit.
- Smoother starts: 3-phase motors start under load without the large inrush current spike of single-phase motors. No voltage sag, no lights flickering when the compressor kicks on.
- Simpler motor construction: 3-phase motors have no start capacitors, no centrifugal switches, fewer failure points.
- 460V specific: 460V 3-phase is common in manufacturing facilities and industrial buildings. Draws approximately half the amperage per leg of the 230V equivalent — better for long wire runs from panel to compressor.
20 CFM at 100 PSI — Production Shop Capacity
- CFM output: 20 CFM @ 100 PSI (confirmed from Castair's published specifications)
- 1/2-inch impact wrench: 4-8 CFM — two running simultaneously with capacity to spare
- 3/8-inch air ratchet: 4-6 CFM — multiple techs on ratchets simultaneously
- DA sander: 12-20 CFM — one sander at a time at this output level
- HVLP spray gun: 9-14 CFM — one gun, stable pressure
- 1-inch impact: 10-25 CFM — intermittent use fine; sustained heavy use should step up to 7.5HP
- General shop tools, blow guns, inflation: Well within capacity
Horizontal Tank Configuration
- Dimensions: 64×32×44" (L×W×H) — 470 lbs
- Low profile: 44-inch height fits under most work surfaces and suits shops with lower ceilings.
- 64-inch floor length: Measure available wall space before committing to horizontal. You need roughly 64 inches of linear run plus service clearance.
- Alternative: R538VG11 or R538VP75 for the vertical configuration — same output, smaller floor footprint.
Castair Build Quality
- 100% duty cycle: Rotary screw design — runs continuously without thermal limitations of piston compressors.
- Cast iron construction throughout: Castair builds with cast iron. Not aluminum. Handles shop thermal cycles and long-term vibration.
- Industrial 1725 RPM motor, full 15% service factor: Commercial-grade motor built for sustained use.
- Single solenoid air end control: No computers, no lockout codes, no proprietary diagnostics. Field-repairable by any competent tech.
- Analog pressure and temperature gauges standard: Read at a glance.
- High pressure and dual high temperature shutdown standard: Protection built in — not an upsell option.
- Factory-filled with Cast-Lube synthetic oil: 4,000-hour or one-year change interval.
- Built-in air/oil separator with spin-on filter: Keeps oil out of the air supply. Standard spin-on replacement.
- Off-shelf V-belts with adjustable tensioner: No proprietary parts. Buy replacements at any industrial supply.
- Air/oil lines in copper pipe: Heat and vibration resistant. Standard plumbing fittings.
- Air-cooled aftercooler/oil cooler standard: Removable for cleaning. Reduces oil temperature and moisture carryover.
- Hour meter standard: Schedule maintenance by actual run hours.
- 10-minute auto shutdown timer: No air demand for 10 minutes, unit shuts off. Electricity savings in real use.
- ASME-rated 80-gallon tank: Code-compliant. Required for commercial insurance and inspection.
- Pre-wired magnetic starter and controls: Connect incoming 460V 3-phase power and run.
- Pressure options: 135 PSI standard, 150 or 175 PSI available.
- 2-year warranty on air end, electric motor, and tank
- Made in Spicer, Minnesota
Available Configurations — 5HP 3-Phase Lineup
- R538HP75 / R538HP75-230: 5HP, 3-Phase 230V, 80 Gal Horizontal — 20 CFM @ 100 PSI — 64×32×44" — 470 lbs
- R538VP75 / R538VP75-230: 5HP, 3-Phase 230V, 80 Gal Vertical — 20 CFM @ 100 PSI — 34×26×70" — 470 lbs
- R538HP75-460: 5HP, 3-Phase 460V, 80 Gal Horizontal — 20 CFM @ 100 PSI — 470 lbs
- R538VP75-460: 5HP, 3-Phase 460V, 80 Gal Vertical — 20 CFM @ 100 PSI — 470 lbs
- R538HG11: 5HP, 3-Phase, 80 Gal Horizontal, G11 air end
- R538VG11: 5HP, 3-Phase, 80 Gal Vertical, G11 air end
- Step up — R738HP75 / R738VP75: 7.5HP, 3-Phase, 80 Gal — 31 CFM @ 100 PSI — 546 lbs
- Single-phase option: R518HP75 / R518VP75 — 5HP, 1-Phase — 20 CFM @ 100 PSI — 480 lbs
When Does a Shop Need This vs. Stepping Up or Down?
- Right for: 3-phase shop, 1-3 bays, one primary tech running air tools steadily. The 20 CFM output handles sustained single-tech production without hesitation.
- Step up to 7.5HP if: Two or more techs consistently run air tools simultaneously. 31 CFM @ 100 PSI covers the overlap. The 7.5HP unit is only slightly larger physically but delivers 55% more output.
- Choose 1-phase if: No 3-phase service available. The single-phase 5HP units (R518HP75/VP75) deliver the same 20 CFM but draw more amperage per leg.
- Voltage confirmation: If your facility runs 230V 3-phase, order the 230V variant instead.
- G11 vs. P75 air end: Both deliver the same output. The air end determines which maintenance kit and filters apply. Confirm which you're ordering before buying PM supplies.
Technical Specifications
- Model: R538HP75-460
- Horsepower: 5 HP
- Phase: 3-Phase
- Voltage: 460V
- Tank: 80 gallon, horizontal, ASME-rated
- Air End: P75
- CFM @ 100 PSI: 20
- Dimensions (L×W×H): 64×32×44"
- Weight: 470 lbs
- Compressor Type: Rotary screw
- Duty Cycle: 100%
- Standard Pressure: 135 PSI (150 or 175 PSI optional)
- Motor Speed: 1725 RPM industrial, full 15% service factor
- Drive: Belt drive, off-shelf V-belts with adjustable tensioner
- Lubrication: Oil-injected, Cast-Lube synthetic, 4,000-hour/1-year interval
- Controls: Single solenoid, pre-wired magnetic starter, analog gauges, hour meter, 10-minute auto shutdown
- Shutdowns: High pressure, dual high temperature (standard)
- Maintenance Kit: MKP75
- Warranty: 2-year on air end, electric motor, and tank
- Manufacturer: Castair, Inc. (Spicer, Minnesota)
What's in the Box
- Castair rotary screw compressor (P75 air end) mounted on 80-gallon horizontal ASME tank
- Pre-wired magnetic starter and controls for 460V 3-phase power
- Air/oil separator with spin-on filter
- Air-cooled aftercooler/oil cooler
- Hour meter
- Pre-filled with Cast-Lube synthetic oil
- Analog pressure and temperature gauges installed
Recommended Accessories
- Preventative Maintenance Kit (MKP75): 2 air filters, 4 oil filters, 1 separator filter, 5 gallons Cast-Lube synthetic oil — 10% savings
- Auto Tank Drain SDV03M: Automatic condensate purging
- Vibration Pads VP1004: 4"×4"×1" set of 4
- Ball Valve BV75 (3/4"): Full-flow outlet shutoff
- Metal Flex Hose VA075 (3/4" NPT × 18"): Vibration isolation between tank and shop plumbing
Why Buy From Air Compressor Factory Direct?
- Castair specialist: We know the 3-phase lineup, voltage variants, and the right accessories for each configuration
- Free shipping on qualifying orders
- Free technical support: Call 866-217-0063 — confirm your voltage, CFM needs, and tank orientation before ordering
- Full manufacturer warranty honored and supported
- Honest guidance: Tell us your setup and we'll confirm whether 5HP is right or if you need 7.5HP
Call 866-217-0063 for quick answers and help!
