The Castair I738HC1 is a 7.5 HP, 3-phase industrial air compressor on an 80-gallon horizontal ASME tank — identical to the I738HC1-S except the magnetic motor starter is not included. This is the right choice for shops that have an existing motor control panel, a machine control center that will handle the overload protection, or an electrician who will source and mount the starter separately. The compressor itself — C1 pump, motor, 80-gallon horizontal tank, belt drive — is the same as the -S version.
Output is 32.4 CFM at 0 PSI and 24.8 CFM at 175 PSI from the C1 pump running at 895 RPM. Dimensions are 64x20x48 inches, shipped weight 625 lbs. If you need a factory-mounted starter, order the I738HC1-S instead.
Starter vs. No Starter — What You're Deciding
3-phase motors require overload protection — a magnetic motor starter. When you buy the I738HC1 without the -S suffix, you are responsible for sourcing and mounting the starter. For this unit at 208/230V 3-phase, the appropriate Castair starter is the S72 with B36 heaters. At 460V, it's the S74 with B22 heaters. Your electrician can also use an equivalent-rated starter from another manufacturer. Call us if you need help specifying the right starter for your service voltage.
Pump Features — Cast Iron C1 Two-Stage
- All cast iron construction: Cylinders, heads, and crankcase — cast iron throughout, not aluminum
- Slow 895 RPM operation: Belt-drive reduction from the 1,725 RPM motor keeps heat low and pump life long
- Tapered roller bearings at both crankshaft ends: Handles radial and thrust loads better than ball bearings under continuous service
- Precision steel connecting rods: Automotive-type rod insert bearings at crankshaft, needle bearings at wrist pin
- Disc and spring valves: Easy to service, reliable under sustained pressure cycling
- 4-ring pistons: Reduced oil carry-over into the discharge air
- Centrifugal unloader: No-load start on every cycle — head pressure releases before the motor cranks up
Tank and Frame Features
- 80-gallon horizontal ASME-rated tank: Powder coated, channel-supported base for stable floor installation
- ASME safety valve: Factory installed, rated for working pressure
- Metal belt guard: Fully enclosed — not a plastic clip-on
- Copper discharge and unloader tube: Better heat dissipation than rubber or plastic lines
Motor
- 1,725 RPM heavy-duty industrial motor: Full 15% service factor — continuous duty rated
- 3-phase: Requires magnetic motor starter for overload protection (not included — see -S version for factory-mounted starter)
What's in the Box
- Castair I738HC1 compressor assembly (C1 pump, motor, 80-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 I738HC1-S for the starter-included version
Available Configurations — 7.5HP 3-Phase Industrial Lineup
- I738HC1-S: 7.5HP, 3-phase, 80-gal horizontal, C1 pump, 895 RPM, 24.8 CFM@175PSI, 64x20x48 in., 625 lbs, magnetic starter included
- I738HC1: Same as above without factory-mounted magnetic starter
- I738HC2-S: 7.5HP, 3-phase, 80-gal horizontal, C2 pump, 585 RPM, 28.1 CFM@175PSI, 64x20x46 in., 730 lbs, magnetic starter included
- I738HC2: Same as above without factory-mounted magnetic starter
- I738VC1-S: 7.5HP, 3-phase, 80-gal vertical, C1 pump, 895 RPM, 24.8 CFM@175PSI, 32x24x74 in., 625 lbs, magnetic starter included
- I738VC1: Same as above without factory-mounted magnetic starter
- I738VC2-S: 7.5HP, 3-phase, 80-gal vertical, C2 pump, 585 RPM, 28.1 CFM@175PSI, 40x24x74 in., 730 lbs, magnetic starter included
- I738VC2: Same as above without factory-mounted magnetic starter
- I7312HC2-S: 7.5HP, 3-phase, 120-gal horizontal, C2 pump — maximum reserve for high-demand shops
When Does a Shop Need This vs. Stepping Up or Down
The I738HC1-S is right for your shop if: You have 3-phase power, your shop runs general automotive service — impacts, ratchets, tire equipment, blow guns — and you want an 80-gallon reserve so the compressor isn't cycling constantly throughout the day. The 24.8 CFM at 175 PSI handles two to three air tools simultaneously without starving them.
Step up to I738HC2-S if you need more CFM — 28.1 vs. 24.8 at 175 PSI. The C2 pump's extra output matters when you're running DA sanders, spray guns, air chisels, or multiple bays simultaneously. The C2 also runs at a lower 585 RPM, which is quieter and produces less heat per hour of operation.
Step up to I7312HC2-S (120-gallon) if your shop runs sustained operations like production spray painting, sandblasting, or line work where the compressor needs maximum reserve to prevent short-cycling on heavy tools.
Consider I738VC1-S if your floor space is tighter and you can use vertical height instead of horizontal floor area.
Technical Specifications
- Model: I738HC1
- Horsepower: 7.5 HP
- Phase: 3-phase
- Tank Capacity: 80 gallons
- Tank Type: Horizontal, ASME-rated, powder coated
- Tank Dimensions: 64 x 20 x 48 in. (L x W x H)
- Shipping Weight: 625 lbs
- Pump Model: C1 (two-stage, cast iron, inline-2)
- Pump RPM: 895
- CFM @ 0 PSI: 32.4
- CFM @ 175 PSI: 24.8
- Max Working Pressure: 175 PSI
- Motor Speed: 1,725 RPM
- Starter: Not included (see I738HC1-S for starter-included version)
- Compatible Starter (208/230V): S72 with B36 heaters
- Compatible Starter (460V): S74 with B22 heaters
- Discharge Tube: Copper
- Belt Guard: Metal, fully enclosed
Why Buy From Air Compressor Factory Direct?
We specialize in industrial and commercial air compressors and have been at it since 2016. When you call, you're talking to someone who knows the Castair lineup, can tell you whether the C1 or C2 pump fits your shop's CFM requirements, and can help you decide between horizontal and vertical tank configurations for your space. Free shipping, free technical support at 866-217-0063, full Castair manufacturer warranty. Call us before you buy if you have questions about which configuration is right for your shop.
Call 866-217-0063 for quick answers and help!
