Castair 3HP 3-Phase Rotary Screw Base Mount Compressor — R33BMP50-23
The Castair R33BMP50-23 is a 3-horsepower, 3-phase, 230-volt rotary screw compressor in base mount configuration — meaning the compressor assembly ships without a tank, intended to be mounted to your existing receiver. If your shop already has a working receiver tank and you're looking to replace a tired piston pump with a continuous-duty rotary screw, this is the unit. Three-phase 230V operation means smoother motor starts, lower amp draw compared to equivalent single-phase motors, and better longevity in a commercial setting where 3-phase power is available.
Note: Detailed specifications for the R33BMP50-23 were not listed individually on Castair's website at time of writing. The information below is based on Castair's confirmed rotary screw product line and standard base mount specifications. Contact us at 866-217-0063 for current data sheet.
3-Phase vs. Single-Phase: Why It Matters in a Shop Setting
- Smoother starts: 3-phase motors start under load without the voltage sag that can trip breakers or dim lights on single-phase circuits. If you have 3-phase service, use it.
- Lower amp draw for same horsepower: A 3HP 3-phase motor draws significantly less amperage than a 3HP single-phase motor. Smaller wire runs, smaller breaker, less heat.
- Longer motor life: Three-phase motors have simpler windings with no start capacitors to fail. In a production environment, this translates to fewer service interruptions.
- 230V vs. 460V: The R33BMP50-23 is wired for 230V 3-phase. If your panel runs 460V 3-phase, look at the 460V variant. Confirm your panel voltage before ordering.
Base Mount Configuration — Flexible Installation
- No tank included: This unit is the compressor assembly only — air end, motor, belt drive, controls, and base frame. You provide the receiver tank.
- Mount to existing tank: Ideal for replacing a worn piston compressor head while keeping a serviceable receiver in place.
- Remote mounting: If your shop layout puts the compressor in one location and the tank in another, a base mount unit with copper piping between them is a clean solution.
- 50-gallon receiver sizing: At 3HP output, a 50-gallon tank provides adequate buffer for intermittent demand. For continuous heavy use, a larger tank reduces cycling frequency.
Castair Build Quality — What You're Getting
- Cast iron construction throughout: Castair builds with cast iron — not aluminum heads. Handles thermal cycling and vibration in real shop conditions.
- Industrial 1725 RPM motor with 15% service factor: Runs cool, lasts longer than consumer-grade motors. Full service factor means it handles the occasional heavy demand without overheating.
- Single solenoid air end control: No computers, no lockout codes. A solenoid either opens or closes. When something fails, any competent technician can diagnose and repair it.
- Pressure and temperature gauges standard: Analog. Readable at a glance. No menu navigation required.
- High pressure and dual high temperature shutdown: Protects the air end from overheat and the system from overpressure. Standard protection, not an option.
- Factory-filled with Cast-Lube synthetic oil: 4,000-hour or one-year change interval. Ships ready to run.
- Built-in air/oil separator with spin-on filter: Keeps oil carryover out of your lines. Standard spin-on replacement — not proprietary.
- Off-shelf V-belts with adjustable tensioner: Standard belts. Order replacements at any industrial supply, not through a factory parts department.
- Air/oil lines in copper pipe: Not plastic hose. Copper handles heat and vibration. Fittings are standard plumbing hardware.
- Air-cooled aftercooler/oil cooler standard: Removable for cleaning. Keeps oil temps stable, reduces moisture in the air stream.
- Hour meter standard: Know exactly when maintenance is due based on actual run hours.
- 10-minute auto shutdown timer: No demand for 10 minutes, the unit shuts off. Saves electricity during slow periods.
- Pressure options: 135 PSI standard. Can be ordered at 150 or 175 PSI.
- 2-year warranty on air end, electric motor
Available Configurations — 3-Phase Rotary Screw Lineup
The R33BMP50-23 is the 3-phase 230V base mount entry. Related models with tanks:
- 5HP, 3-Phase, 80 Gal Vertical (R538VP75): 20 CFM @ 100 PSI — 470 lbs
- 5HP, 3-Phase, 80 Gal Horizontal (R538HP75): 20 CFM @ 100 PSI — 470 lbs
- 7.5HP, 3-Phase, 80 Gal Vertical (R738VP75): 31 CFM @ 100 PSI — 546 lbs
- 7.5HP, 3-Phase, 80 Gal Horizontal (R738HP75): 31 CFM @ 100 PSI — 546 lbs
When Does a Shop Need This vs. Stepping Up or Down?
- Right for: Small shop with 3-phase power, existing receiver tank, and light-to-moderate air demand. One tech running air tools intermittently — tire shop, small repair bay, service department.
- Step up to 5HP if: You're running multiple air tools simultaneously or your demand is continuous. The 5HP 3-phase unit (R538VP75/HP75) delivers 20 CFM @ 100 PSI — noticeably more headroom for production work.
- Base mount is right when: You have a functional tank and need a better compressor head. Don't pay for a tank you don't need.
- Check your voltage first: 230V 3-phase and 460V 3-phase are not interchangeable. Know your panel before ordering.
Technical Specifications
- Model: R33BMP50-23
- Horsepower: 3 HP
- Phase: 3-Phase
- Voltage: 230V
- Configuration: Base mount (no tank)
- Suggested Receiver: 50 gallon
- Compressor Type: Rotary screw
- Duty Cycle: 100%
- Standard Pressure: 135 PSI (150 or 175 PSI available)
- Lubrication: Oil-injected, synthetic lubricant
- Drive: Belt drive, standard V-belts
- Motor Speed: 1725 RPM industrial motor
- Controls: Single solenoid, pre-wired magnetic starter, hour meter, 10-minute auto shutdown
- Warranty: 2-year on air end and electric motor
- Manufacturer: Castair (Spicer, Minnesota)
Detailed CFM, dimensions, and weight pending manufacturer confirmation. Call for current spec sheet.
What's in the Box
- Castair rotary screw compressor assembly (air end, motor, belt drive, base frame)
- Pre-wired magnetic starter and controls (just connect 3-phase 230V power)
- Air/oil separator with spin-on filter
- Air-cooled aftercooler/oil cooler
- Hour meter
- Pre-filled with Cast-Lube synthetic oil
Tank not included. 50-gallon receiver sold separately.
Why Buy From Air Compressor Factory Direct?
- Castair specialists: We know the lineup — base mounts, voltage configurations, tank sizing, maintenance kits
- Free shipping on qualifying orders
- Free technical support: Call 866-217-0063 — talk to someone who understands 3-phase installations and rotary screw systems
- Full manufacturer warranty honored and supported
- Honest guidance: Not sure if this is the right unit? We'll help you figure out what your shop actually needs
Call 866-217-0063 for quick answers and help!
