The Castair I10312VC3-S is a 10-horsepower, 3-phase industrial air compressor built for shops that run heavy air tools continuously and need a machine that will hold up for decades, not years. This is the large-pump, slow-RPM version of the 10HP 3-phase line — the C3 pump configuration means a bigger cast iron pump running at just 570 RPM instead of 758 RPM, which translates directly into lower operating temperatures, less wear, and a noticeably quieter shop. The 120-gallon vertical tank keeps your floor footprint tight while giving you the storage capacity to handle intermittent high-demand tools without constant pump cycling. The included magnetic motor starter (the -S suffix) means this unit ships ready to wire and run.
Who Needs This Compressor
This is a shop-grade machine for busy automotive, truck, and general industrial shops running multiple air tools at once. If your shop is running 3–4 impact wrenches, spray guns, sandblasters, or air-powered lifts simultaneously on 3-phase power, the I10312VC3-S delivers 35.0 CFM at 175 PSI — enough to keep those tools fed without struggling. The vertical 120-gallon tank is the right call for shops where floor space is tight but ceiling height is available.
If you are on single-phase power, look at the I10112VC3-S instead. If your shop consistently runs more than 35 CFM at pressure, consider stepping up to the 15HP line.
Pump — Where Castair Does Things Differently
The C3 pump designation is the key differentiator in this model. Here is what that means in practice:
- All cast iron construction — cylinders, heads, crankcase. Cast iron dissipates heat better than aluminum and holds up to years of hard use without warping or wear problems.
- 570 RPM operating speed — this is significantly slower than most competitors running 900–1200 RPM. Slower RPM means cooler running, less wear on rings and bearings, and a pump that can realistically outlast the building it sits in.
- Tapered roller bearings at both ends of the crankshaft — not ball bearings, not one-end support. Tapered roller bearings handle the thrust loads of a reciprocating pump correctly and last longer under sustained load.
- Precision steel connecting rods with automotive-type insert bearings — at both the crankshaft and wrist pin. This is how heavy-duty industrial engines are built. The insert bearings are replaceable, which matters for long-term serviceability.
- Disc and spring valves — easier to service than reed valves, more reliable under high-cycle commercial use. When a valve wears out, you can service it without pulling the pump apart entirely.
- 4-ring pistons — four compression/oil rings per piston means better sealing efficiency and significantly less oil carry-over into the air stream compared to 2-ring pistons found on lesser pumps.
- Centrifugal unloader — the pump starts under no load every time, which protects the motor from inrush torque damage and extends motor life.
Tank, Motor, and Controls
- 120-gallon vertical ASME-certified tank — powder coated, with four legs for stable floor mounting.
- ASME safety valve — required by code, properly rated for this pump output.
- Heavy-duty 1725 RPM industrial motor — 15% service factor or higher. A motor with a 15% service factor can handle sustained loads 15% above nameplate rating without damage.
- Totally enclosed metal belt guard — keeps debris out of the belt drive and keeps fingers away from moving parts.
- Copper discharge and unloader tube — or stainless-steel braided flex line. Both handle heat better than rubber and last longer in a hot pump compartment.
- Magnetic motor starter (included) — factory-mounted and wired. The starter provides overload protection for the motor and allows proper 3-phase wiring with a single contactor.
Available Configurations in the 10HP 3-Phase Line
- I1038VC2-S — 10HP, 3-phase, 80-gallon vertical, C2 pump (758 RPM), 45.0/35.0 CFM, 40x24x74 in., 770 lbs.
- I1038HC2-S — 10HP, 3-phase, 80-gallon horizontal, C2 pump (758 RPM), 45.0/35.0 CFM, 64x20x46 in., 770 lbs.
- I10312VC2-S — 10HP, 3-phase, 120-gallon vertical, C2 pump (758 RPM), 45.0/35.0 CFM, 44x30x75 in., 860 lbs.
- I10312HC2-S — 10HP, 3-phase, 120-gallon horizontal, C2 pump (758 RPM), 45.0/35.0 CFM, 69x24x50 in., 860 lbs.
- I10312VC3-S (this unit) — 10HP, 3-phase, 120-gallon vertical, C3 pump (570 RPM), 45.0/35.0 CFM, 44x30x75 in., 1025 lbs. Slower pump, quieter, longer-lived.
- I10312HC3-S — 10HP, 3-phase, 120-gallon horizontal, C3 pump (570 RPM), 45.0/35.0 CFM, 69x24x50 in., 1025 lbs.
Factory Options
- Low oil shutdown — #6304M. Recommended for unattended operation.
- Hour meter — #HRM460M (460V) or #HRM75M (230V).
- Electronic auto drain — #SDV03M. Timed automatic tank drain.
- Dual control — #DC3 (standard on C3 units). Load/unload mode for energy savings.
- Intake noise silencer — #SA100x2M.
- Belt tensioner — #215DM (7.5 and 10HP units).
- Beltguard aftercooler — #BGAC1M (35 CFM, fits 5/7/10HP).
- All Options C3 package — #AOC3 (10% off all asterisk options).
- Vibration pads — #VP1004, set of 4 (4x4x1 inch).
- Right from the Start Kit — #RFS002 (C3 units).
When Does a Shop Need the I10312VC3-S vs Stepping Up or Down
This is the right compressor if:
- You are on 3-phase power and need 10HP capacity
- Your shop runs continuously through the day and you want the lowest possible RPM for longevity and quiet operation
- You need 120 gallons of storage but have limited floor space — the vertical tank fits in a 44x30 inch footprint
- You want the magnetic starter included rather than sourcing it separately
Consider stepping down to the I10312VC2-S or I1038VC2-S if:
- Budget is a consideration — the C2 pump delivers the same CFM output at lower cost
- Your shop has moderate duty cycles and the compressor is not running under heavy load all day
Consider stepping up to the 15HP line if:
- Your shop consistently demands more than 35 CFM at 175 PSI
- The 15HP I15312VC2-S delivers 45.3 CFM at 175 PSI and the I15312VC3-S pushes 50.2 CFM at 175 PSI
Technical Specifications
- Model Number: I10312VC3-S
- Horsepower: 10 HP
- Phase: 3-phase
- Tank Capacity: 120 gallons, vertical
- Pump RPM: 570
- CFM @ 0 PSI: 45.0
- CFM @ 175 PSI: 35.0
- Max Pressure: 175 PSI
- Dimensions (LxWxH): 44 x 30 x 75 inches
- Weight: 1,025 lbs
- Motor Speed: 1725 RPM
- Motor Service Factor: 15% minimum
- Tank Certification: ASME
- Magnetic Starter: Included (factory mounted)
- Pump Configuration: C3
Why Buy From Air Compressor Factory Direct?
We have specialized in industrial air compressors since 2016. When you call, you talk to someone who understands the difference between a C2 and C3 pump, which options matter for your application, and how to match this compressor to your shop electrical service. Free shipping, free pre-sale technical support, and full manufacturer warranty on every unit.
Call 866-217-0063 for quick answers and help!
