The Castair I733HC2 is a 7.5 HP, 3-phase industrial air compressor on a 30-gallon horizontal ASME tank with the C2 pump — sold without the factory-mounted magnetic motor starter. This is the base unit for shops that already have a starter panel in place, prefer to use their own overload protection, or want to spec their own controls independently. The compressor itself — pump, motor, tank, and drive — is identical to the I733HC2-S. The only difference is the magnetic starter is not included here.
The C2 pump runs at 585 RPM, producing 35.0 CFM at 0 PSI and 28.1 CFM at 175 PSI. It's a two-stage, V4 cast iron pump — heavier displacement than the C1, with a lower shaft speed that keeps heat and wear in check over a long service life. If you need the higher CFM of the C2 pump but your electrician or shop manager prefers to handle the motor controls separately, the I733HC2 without the starter is the correct choice.
Starter vs. No Starter — What the -S Suffix Means
In Castair's industrial lineup, the -S suffix means the magnetic motor starter is factory-mounted and wired to the unit. When you see a model without that suffix (like I733HC2), the starter is not included. This matters for a few reasons:
- 3-phase motors require overload protection: You will need a magnetic motor starter. If you buy the I733HC2, you'll source and mount your own starter — either a Castair unit or equivalent sized for 7.5HP, 3-phase at your voltage (208/230V or 460V)
- Existing panel: Some shops have a compressor panel or motor control center already in place. Buying without the factory starter avoids paying for a duplicate
- Wiring flexibility: Without the pre-mounted starter, your electrician has more flexibility in how they run conduit and position the disconnect
If you're not sure whether to order with or without the starter, call us. We'll ask about your electrical service and walk you through the right choice.
Pump Features — Cast Iron C2 Two-Stage V4
- All cast iron V4 cylinder configuration: Four cylinders in a V arrangement — more displacement and higher CFM than the C1 inline-2, at lower shaft speed
- Slow 585 RPM operation: Lower heat, less wear, quieter operation than faster-turning pumps
- Tapered roller bearings at both crankshaft ends: Superior support for two-stage compression loads and belt-drive side loads
- Precision steel connecting rods: Automotive-type insert bearings at crankshaft, needle bearings at wrist pin
- Disc and spring valves: Field-serviceable, reliable under sustained pressure cycling
- 4-ring pistons: Lower oil carry-over into the discharge air stream
- Centrifugal unloader: No-load start on every cycle — pressure is released before the motor cranks up
Tank and Frame Features
- 30-gallon horizontal ASME-rated tank: Powder coated, channel-base horizontal configuration
- ASME safety valve: Factory installed
- Metal belt guard: Fully enclosed
- Copper discharge and unloader tube: Handles heat and pressure cycling better than rubber or plastic
Motor
- 1,725 RPM heavy-duty industrial motor: Full 15% service factor — designed for continuous shop duty
- 3-phase: Requires magnetic starter for overload protection (not included — see I733HC2-S for the starter-included version)
What's in the Box
- Castair I733HC2 compressor assembly (C2 pump, motor, 30-gal horizontal tank, belt drive, belt guard)
- ASME safety valve (installed)
- Copper discharge and unloader tube (installed)
- Pressure switch (installed)
- Magnetic motor starter not included — order I733HC2-S for the starter-included version
Available Configurations — 7.5HP 3-Phase Industrial Lineup
- I733HC1-S: 7.5HP, 3-phase, 30-gal horizontal, C1 pump, 895 RPM, 24.8 CFM@175PSI, magnetic starter included
- I733HC2-S: 7.5HP, 3-phase, 30-gal horizontal, C2 pump, 585 RPM, 28.1 CFM@175PSI, magnetic starter included
- I733HC2 (this unit): 7.5HP, 3-phase, 30-gal horizontal, C2 pump, 585 RPM, 28.1 CFM@175PSI, no starter
- I738HC2-S: 7.5HP, 3-phase, 80-gal horizontal, C2 pump, 585 RPM, 28.1 CFM@175PSI — 64x20x46 in., 730 lbs, starter included
When Does a Shop Need This vs. Stepping Up or Down
Choose the I733HC2 when you need the C2 pump's higher CFM output (28.1 CFM@175PSI), already have motor controls in your shop's panel, and don't need or want a factory-mounted starter. This is common in shops that run multiple compressors from a central control panel or where the electrical contractor handles the motor control separately.
Buy the I733HC2-S instead if you don't have existing motor controls — the factory starter is cleaner, saves field labor, and ensures the overload protection is correctly sized for this motor from day one.
Step up to I738HC2-S for an 80-gallon tank — more reserve air for sustained spray painting, sandblasting, or multi-bay operations.
Technical Specifications
- Model: I733HC2
- Horsepower: 7.5 HP
- Phase: 3-phase
- Tank Capacity: 30 gallons
- Tank Type: Horizontal, ASME-rated, powder coated
- Pump Model: C2 (two-stage, cast iron, V4)
- Pump RPM: 585
- CFM @ 0 PSI: 35.0
- CFM @ 175 PSI: 28.1
- Max Working Pressure: 175 PSI
- Motor Speed: 1,725 RPM
- Pump Stage: Two-stage
- Pump Cylinder Configuration: V4
- Starter: Not included (see I733HC2-S for starter-included version)
- Discharge Tube: Copper
- Belt Guard: Metal, fully enclosed
Why Buy From Air Compressor Factory Direct?
We specialize in Castair industrial compressors and know this lineup thoroughly. If you're unsure whether to buy with or without the starter, or whether the C1 or C2 pump is right for your shop's CFM requirements, call us. We've been matching shops to the right compressor since 2016. Free shipping, free tech support, full manufacturer warranty. No sales pressure — just honest answers.
Call 866-217-0063 for quick answers and help!
