The Castair D10112HC2-S is a 20 total horsepower duplex two-stage air compressor on a 120-gallon horizontal tank, wired for single-phase electricity. It runs two 10 HP cast iron pumps simultaneously through a magnetic starter — already mounted and wired from the factory — and delivers 70 CFM at 175 PSI. At 1,470 lbs and $price, this is a serious production floor compressor for shops that need high sustained output on single-phase power and the built-in redundancy of a true duplex setup.
Why Duplex and Why This Model
A duplex compressor runs two complete pumps — each with its own motor, pump, and controls — on a shared tank. The two units alternate or run simultaneously depending on demand. The practical benefit: if one pump needs service, the other keeps the shop running. For a production shop where downtime means idle lift bays, the duplex setup pays for itself the first time you avoid shutting down for a pump repair.
The D10112HC2-S specifically is the single-phase 120-gallon configuration. The HC2 pump runs at 758 RPM — slower than standard industrial pumps — which reduces heat buildup, extends valve life, and cuts noise compared to a high-RPM unit of equivalent output. The single-phase rating (with magnetic starter included) means you can run this on a standard 240V single-phase service without installing three-phase.
Pump and Motor Specifications
- Configuration: Duplex (two pumps, two motors)
- Total HP: 20 HP (2 x 10 HP)
- Phase: Single-phase
- Pump RPM: 758 (HC2 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): 85" x 28" x 57"
- Weight: 1,470 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 (758 RPM) reduces heat and extends valve life
- Tapered roller bearings at both ends of crankshaft for superior support and reduced friction
- Precision steel connecting rods with automotive-type rod insert bearings at crankshaft and bearings at wrist pin
- Disc and spring valves for easy service, higher efficiency, and reliability
- 4-ring pistons for higher efficiency and less oil carry-over
- Centrifugal unloader for loadless start-up every time
Factory-Mounted Options Available
The D10112HC2-S ships with the magnetic starter mounted and wired. Additional factory-installed options are available at order time:
- Low Oil Control — #6304x2M
- Hour Meter 230V — #HRM75x2M | 460V — #HRM460x2M
- Alternator — #ALT230M | #ALT460M
- Electronic Auto Drain — #SDV03M
- Dual Control (C2 version) — #DC2x2M
- Intake Noise Silencers (C2) — #SA100x4M
- Belt Tensioner (7.5-10HP) — #215Dx2M
- Right From the Start Kit — #RFS001D (10HP units)
- Vibration Pads (set of 4) — #VP1004
- Beltguard Aftercooler (up to 70 CFM) — #BGAC1x2M
- All Options C2 Package — #AOC2D
D10112HC2-S vs. Other Duplex Configurations
The duplex lineup at the 2x10HP level gives you several choices:
- D10112HC2-S — 2x10HP, 1-phase, 120gal horizontal, 758 RPM, 70 CFM @ 175 PSI, 1,470 lbs (this unit)
- D10124HC2-S — Same pump/motors, 240-gallon horizontal tank, 1,820 lbs — more storage for high-demand shops
- D10112HC3-S — 2x10HP, 1-phase, 120gal horizontal, 570 RPM HC3 pump, 94x28x57 frame, 1,800 lbs — slower pump for even quieter, cooler operation
- D10124HC3-S — HC3 pump, 240-gallon tank, 2,150 lbs — maximum storage with the slower pump
- D10312HC2-S — 2x10HP, 3-phase, 120gal — same output as D10112HC2-S but on three-phase power
- D10324HC2-S — 3-phase, 240-gallon — three-phase with maximum storage
When Does a Shop Need This vs. Stepping Up or Down
This unit fits a shop that: Runs on single-phase 240V power (no three-phase service available), needs 60-70 CFM sustained output, runs multiple air tools or a paint booth simultaneously, and wants the peace of mind that comes from a duplex setup — one pump can keep the shop running while the other is serviced.
Step down to a single Industrial Series if you run one or two tools at a time, rarely exceed 35-45 CFM demand, and do not need redundancy. A single 10HP I10112HC2-S delivers 35 CFM at 175 PSI at significantly lower cost and weight.
Step up to the D10124HC2-S (240-gallon tank) if your shop has high peak demand that exhausts a 120-gallon tank before the pumps can catch up — busy collision shops, sandblasting operations, or spray painting with long continuous draw cycles.
Step up to three-phase (D10312HC2-S or D10324HC2-S) if you have three-phase service available; three-phase motors run cooler, last longer, and are more efficient at this horsepower level.
Technical Specifications Summary
- Model: D10112HC2-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: 758
- CFM @ 0 PSI: 90
- CFM @ 175 PSI: 70
- Tank: 120 gallon, horizontal, ASME, powder coated
- Dimensions (LxWxH): 85" x 28" x 57"
- Weight: 1,470 lbs
- Magnetic Starter: Included, factory mounted and wired
- Safety Valve: ASME rated, installed
- Belt Guard: Metal, totally enclosed
- Discharge Tube: Copper or stainless-steel braided flex line
Why Buy From Air Compressor Factory Direct?
We have been selling industrial air compressors since 2016 and we know the Cast Air lineup inside out. When you are spending $10,000+ on a duplex compressor, you want to talk to someone who can answer technical questions, help you spec the right configuration for your electrical service and CFM requirements, and make sure it arrives properly. We offer free shipping, free technical support at 866-217-0063, and the full Castair manufacturer warranty. If the D10112HC2-S is not the right configuration for your shop, we will tell you that too — and point you to the one that is.
Call 866-217-0063 for quick answers and help!
