Heavy Duty Shop Air Compressor Industrial Series - Model No. I10312HC3-S

Castair I10312HC3-S — 10 HP Three-Phase Industrial Air Compressor, 120-Gallon Horizontal Tank, Slow-Speed C3 Pump with Mounted Starter

The Castair I10312HC3-S combines three-phase power with Castair's slow-speed C3 cast iron pump on a 120-gallon horizontal ASME tank. The C3 pump runs at 570 RPM — 188 RPM slower than the C2 variant — producing the same 45.0 CFM at 0 PSI and 35.0 CFM at 175 PSI with less heat and less mechanical wear per operating hour. The three-phase motor adds further advantages: lower starting current, cooler running under sustained load, and better long-term durability in continuous service.

At 1,025 lbs and 69 x 24 x 50 inches, this is the heaviest 10 HP horizontal unit in the lineup. The weight is the C3 pump — more cast iron, slower shaft speed, lower operating temperature. If your facility has three-phase power and you plan to run this compressor hard for 20 years, this is the right machine.

Cast Iron Pump Engineering — Why This Matters for Shop Longevity

Every Castair Industrial Series compressor is built around their oversized cast iron pump. Here is what separates these from lighter-duty machines:

• All cast iron construction — cylinder heads, crankcase, and cylinders are cast iron throughout. Cast iron manages heat better than aluminum and wears far more slowly under continuous load.
• Tapered roller bearings at both ends of the crankshaft — not ball bearings. Tapered rollers handle both radial and thrust loads simultaneously, which is exactly what a reciprocating pump crankshaft sees in operation.
• Precision steel connecting rods with automotive-type insert bearings — at both the crankshaft journal and the wrist pin. These are the same bearing design used in automotive engines. They are replaceable when worn — not a throwaway assembly.
• Disc and spring valves — simpler to service than reed valves, more efficient at high discharge pressures, and more reliable over years of cycling.
• 4-ring pistons — two extra rings versus typical 2-ring piston designs. Better compression sealing, significantly less oil carry-over into the air stream.
• Centrifugal unloader — the pump starts unloaded on every cycle without exception. This reduces motor starting current, reduces wear on the motor and belts, and eliminates the hard-start problem common in compressors that attempt to restart against pressure.

C3 + Three-Phase: The Premium Combination

• Slowest pump speed in the 10 HP lineup — 570 RPM on the C3, three-phase motor for coolest operation
• Lowest heat generation — slower pump speed and more efficient motor means less heat buildup over a full business day of operation
• Quietest 10 HP option — both the slow pump speed and three-phase motor contribute to lower noise levels
• Longest expected service life — all other things equal, slower pump speed and three-phase motor mean fewer hours of thermal stress per unit of work done
• 1,025 lbs — heaviest 10 HP horizontal in the lineup, plan accordingly for installation

Tank, Motor, and Controls

• ASME-coded steel tank — powder-coated for corrosion resistance. ASME certification means the tank was designed and tested to a recognized pressure vessel standard, not just stamped with a number.
• ASME safety valve — factory-installed.
• Metal belt guard, totally enclosed — not a plastic cover.
• Copper discharge and unloader tubing or stainless-steel braided flex line — not plastic hose or rubber.
• Heavy-duty 1,725 RPM industrial motor with a minimum 15% service factor. This means the motor can sustain loads above its nameplate rating without tripping. In a shop where the compressor runs all day, the service factor is not a marketing number — it is the difference between a motor that lasts a decade and one that burns up in two years.

Who Buys the C3 Three-Phase

• Shops with three-phase power that plan to own this compressor for 20+ years
• Operations running continuous duty — the compressor cycles most or all of the business day
• Manufacturing environments, fleet maintenance shops, body shops — anywhere that treats the compressor as critical infrastructure
• Buyers focused on lowest total cost of ownership over the life of the machine

What's in the Box

• Castair I10312HC3-S compressor assembly (pump, motor, tank, factory-assembled)
• Factory-mounted and wired magnetic motor starter
• ASME safety valve (installed)
• Pressure switch (installed)
• Metal belt guard (installed)
• Copper discharge and unloader tubing or stainless-steel braided flex line (installed)
• Operator documentation

Factory-installed options available on this unit include: low oil shutdown control (#6304M), hour meter (#HRM75M for 230V or #HRM460M for 460V), air-operated auto drain (#ADVSM), electronic auto drain (#SDV03M), dual controls (#DC2 for C2 pumps), intake noise silencer (#SA100x2M for C2/C3), belt tensioner (#215DM for 10 HP), time delay (#TD100M for 230V), vibration isolation pads (#VP1004), beltguard aftercooler (#BGAC1M — 35 CFM, appropriate for 10 HP), and Right from the Start Kit (#RFS001 for C1/C2). Ordering all asterisk-marked options qualifies for 10% discount on options. Ask us about pre-configured option packages.

Technical Specifications

• Model: I10312HC3-S
• Horsepower: 10 HP
• Phase: 3-phase (three-phase)
• Tank capacity: 120 gallons
• Tank orientation: Horizontal (channel base)
• Pump type: C3 (two-stage cast iron, slow-speed)
• Pump RPM: 570
• CFM at 0 PSI: 45.0
• CFM at 175 PSI: 35.0
• Max working pressure: 175 PSI
• Motor speed: 1,725 RPM
• Motor service factor: 15% minimum
• Dimensions (L x W x H): 69 x 24 x 50 inches
• Weight: 1,025 lbs
• Tank certification: ASME
• Starter: Factory-mounted magnetic motor starter (included)
• Manufacturer: Castair (Cast Air Inc., Spicer, MN)

Available Configurations — Cast Air Industrial 10 HP Three-Phase Lineup

Single-phase versions (I101-series) are available if your facility only has single-phase 230V service.

Why Buy From Air Compressor Factory Direct?

We have been selling industrial air compressors since 2016 and carry the full Cast Air Industrial Series lineup. When you call us, you reach someone who can tell you whether the C2 or C3 pump is right for your application, what electrical service you need, which options are worth adding, and whether horizontal or vertical tank orientation fits your floor plan. We offer free shipping on qualifying orders, full manufacturer warranty support, and straight talk about which unit fits your shop — not a push toward the most expensive option.

Call 866-217-0063 for quick answers and help!