The Castair D10112HC3-S is a 20 total horsepower duplex two-stage air compressor on a 120-gallon horizontal ASME tank, running on single-phase electricity. It uses the HC3 pump configuration — running at 570 RPM, slower than the HC2 — which means quieter operation, lower running temperatures, and longer pump life in exchange for a larger physical footprint (94" x 28" x 57" vs. 85" for the HC2 frame). It delivers 70 CFM at 175 PSI combined from two 10 HP cast iron pumps, with a magnetic starter mounted and wired at the factory.
HC3 vs. HC2 — The Key Difference
The HC2 and HC3 designations refer to the pump size and speed. Both deliver the same rated CFM (90 at 0 PSI, 70 at 175 PSI combined for the 2x10HP configuration), but the HC3 achieves that output at a lower RPM using a larger displacement pump:
- HC2 pump: 758 RPM, 85" frame length, 1,470 lbs
- HC3 pump: 570 RPM, 94" frame length, 1,800 lbs
Slower RPM means the pump runs cooler, valve wear is reduced, and the unit operates more quietly. If your shop has noise-sensitive areas or you plan to run this machine hard for long cycles, the HC3 is worth the extra weight and frame length.
Pump and Motor Specifications
- Configuration: Duplex (two pumps, two motors)
- Total HP: 20 HP (2 x 10 HP)
- Phase: Single-phase
- Pump RPM: 570 (HC3 pump)
- CFM at 0 PSI: 90 CFM combined
- CFM at 175 PSI: 70 CFM combined
- Max Pressure: 175 PSI
- Stage: Two-stage
Tank and Physical Specs
- Tank Capacity: 120 gallons, horizontal ASME
- Dimensions (LxWxH): 94" x 28" x 57"
- Weight: 1,800 lbs
- Tank Finish: Powder coated
- Safety Valve: ASME rated, installed
- Magnetic Starter: Mounted and wired (factory installed)
Cast Iron Pump Features
- All cast iron construction for long service life and quiet operation
- Slow RPM design (570 RPM) — lower than HC2 for even quieter, cooler operation
- Tapered roller bearings at both ends of crankshaft
- Precision steel connecting rods with automotive-type rod insert bearings
- Disc and spring valves for easy service and reliability
- 4-ring pistons for higher efficiency and less oil carry-over
- Centrifugal unloader for loadless start-up
Factory-Mounted Options Available
- Low Oil Control — #6304x2M
- Hour Meter 230V — #HRM75x2M | 460V — #HRM460x2M
- Alternator — #ALT230M | #ALT460M
- Electronic Auto Drain — #SDV03M
- Dual Control (standard on C3) — included on this unit
- Intake Noise Silencers (C2/C3) — #SA100x4M (note: cannot combine with dual control on C3)
- Belt Tensioner (7.5-10HP) — #215Dx2M
- Right From the Start Kit — #RFS001D (10HP)
- Vibration Pads — #VP1004
- Beltguard Aftercooler — #BGAC1x2M
- All Options C3 Package — #AOC3D
Duplex Configuration Comparison — 2x10HP Single-Phase
- D10112HC2-S — 758 RPM HC2 pump, 120gal, 85x28x57, 1,470 lbs — smaller footprint, lighter
- D10112HC3-S — 570 RPM HC3 pump, 120gal, 94x28x57, 1,800 lbs — slower/quieter pump (this unit)
- D10124HC2-S — HC2 pump, 240-gallon tank, 1,820 lbs — more storage
- D10124HC3-S — HC3 pump, 240-gallon tank, 2,150 lbs — max storage + slowest RPM
When Does a Shop Need This vs. Stepping Up or Down
Choose the D10112HC3-S over the D10112HC2-S when: Noise level matters (body shop, customer-facing areas), or the compressor will run extended duty cycles where keeping the pump cool is a priority. The 570 RPM HC3 pump is the better long-term choice for high-utilization shops even though it weighs 330 lbs more and costs more upfront.
Step down to D10112HC2-S if floor space or ceiling height is tight (the HC3 frame is 9" longer), or if budget is the primary constraint — same rated CFM output, just at a higher RPM.
Step up to D10124HC3-S if your shop runs long continuous cycles that exhaust 120 gallons before the pumps catch up — adding 120 gallons of storage smooths out pressure swings during peak demand.
Consider three-phase (D10312HC3-S or D10324HC3-S) if three-phase service is available. Three-phase motors at 10 HP run more efficiently and last longer than single-phase units of equivalent rating.
Technical Specifications Summary
- Model: D10112HC3-S
- Manufacturer: Castair (Cast Air, Inc.) — Spicer, Minnesota
- Configuration: Duplex, two-stage, electric
- Total HP: 20 HP (2 x 10 HP)
- Phase: Single-phase
- Pump RPM: 570 (HC3)
- CFM @ 0 PSI: 90
- CFM @ 175 PSI: 70
- Tank: 120 gallon, horizontal, ASME, powder coated
- Dimensions (LxWxH): 94" x 28" x 57"
- Weight: 1,800 lbs
- Magnetic Starter: Included, factory mounted and wired
- Safety Valve: ASME rated, installed
Why Buy From Air Compressor Factory Direct?
We have been selling industrial air compressors since 2016. The D10112HC3-S is a $12,000+ capital investment and the pump/tank/motor configuration decision matters. We can walk you through the HC2 vs. HC3 comparison, help you choose the right tank size, and advise on electrical service requirements. Free shipping, free technical support at 866-217-0063, and the full Castair manufacturer warranty on every unit we sell.
Call 866-217-0063 for quick answers and help!
