Castair 20 HP Duplex Two-Stage Air Compressor — 70 CFM @ 175 PSI, 120 / 240 Gal ASME Tank
The Castair Duplex 20 HP runs two independent 10 HP pump-and-motor sets on a single ASME-certified horizontal tank — high-volume air for demanding shops, with the security of a built-in backup. Run one pump for lighter loads, run both together for the full 70 CFM at 175 PSI, or let them alternate automatically to share wear, and keep producing air even if one pump is down for service. Dual full cast iron, oil-lubricated pumps deliver up to 90 CFM at 0 PSI. Hand-built to order by Castair, a family-owned Minnesota manufacturer since 1991.
Why It's Different: Each pump uses a V-twin cylinder design for 360-degree cooling, tapered roller bearings at both ends of the crankshaft, and stainless disc-and-spring valves rated for up to 10× the lifespan of competitor reed valves. Slow pump RPM and a larger bore/stroke deliver cooler, quieter operation and longer pump life under heavy duty cycles. A centrifugal unloader gives load-less startups, four-ring pistons minimize oil carry-over, and an oil sight glass makes maintenance checks effortless. Magnetic starter ships mounted and wired.
Best For: Large automotive and truck shops, manufacturing and fabrication facilities, HVAC service operations, and any high-demand plant that needs continuous air with redundancy built in.
Configuration: Choose single-phase or three-phase power, a 120-gallon or 240-gallon ASME tank, and your pump build: standard 758 RPM or slow-speed 570 RPM (larger footprint, heavier, runs cooler). All configurations deliver 90 CFM @ 0 PSI / 70 CFM @ 175 PSI.
⚠️ BEFORE YOU ORDER — PLEASE READ: This is a heavy-duty, built-to-order industrial compressor.
• Electrical: requires a dedicated 208–230V circuit (single-phase or three-phase, per your selected model), installed by a licensed electrician with proper grounding. Magnetic starter comes mounted and wired.
• Lead time: all Castair units are built to order — confirm current production lead time before purchase.
• Weight & placement: 1,410–2,190 lb depending on configuration; requires a level floor rated for the load, adequate ventilation for heat dissipation, and freight handling for delivery.
It is the customer's responsibility to verify electrical service, floor space, and ventilation before purchase and installation.
Features
-
Duplex design — two independent 10 HP pump/motor sets run one, both, or auto-alternating for redundancy
- Up to 90 CFM @ 0 PSI / 70 CFM @ 175 PSI
- Two-stage, dual full cast iron oil-lubricated pumps
-
V-twin cylinder design for 360° cooling and longevity
-
Tapered roller bearings at both ends of the crankshaft for reduced friction
-
Stainless disc & spring valves — up to 10× the lifespan of reed valves
-
Four-ring pistons for higher efficiency and minimal oil carry-over
-
Centrifugal unloader for load-less startups
-
ASME-certified, powder-coated horizontal tank for safety and corrosion resistance
- Rigid metal belt guards, copper discharge & unloader tubes, oil sight glass
-
Magnetic starter mounted & wired standard
- Single-phase or three-phase | 120 or 240 gal tank | Built to order in Minnesota
Specifications
| Castair Duplex 20 HP (2×10 HP) — 90 CFM @ 0 PSI / 70 CFM @ 175 PSI |
| Model |
Phase |
Pump RPM |
Tank (Gal) |
L × W × H (in) |
Weight (lb) |
| D10112HC2-S |
Single |
758 |
120 |
85 × 28 × 57 |
1,470 |
| D10124HC2-S |
Single |
758 |
240 |
85 × 30 × 64 |
1,820 |
| D10112HC3-S |
Single |
570 |
120 |
94 × 28 × 57 |
1,800 |
| D10124HC3-S |
Single |
570 |
240 |
94 × 30 × 64 |
2,150 |
| D10312HC2-S |
Three |
758 |
120 |
85 × 28 × 57 |
1,410 |
| D10324HC2-S |
Three |
758 |
240 |
85 × 30 × 64 |
1,760 |
| D10312HC3-S |
Three |
570 |
120 |
94 × 28 × 57 |
1,740 |
| D10324HC3-S |
Three |
570 |
240 |
94 × 30 × 64 |
2,190 |
| Shared Specifications |
| Manufacturer |
Castair (Spicer, Minnesota — family-owned since 1991) |
| Type |
Two-stage electric duplex air compressor (horizontal tank) |
| Total HP |
20 HP (2 × 10 HP) |
| Output |
90 CFM @ 0 PSI | 70 CFM @ 175 PSI |
| Pump |
Two-stage, dual full cast iron, oil-lubricated, V-twin |
| Voltage |
208–230V, single-phase or three-phase |
| Tank |
120 or 240 gal, ASME-certified, powder-coated horizontal |
| Controls |
Magnetic starter mounted & wired; centrifugal unloader |
| Brand |
Castair |
What's Included
- Dual two-stage cast iron pumps and dual motors on one ASME horizontal tank
- Magnetic motor starter — mounted and wired
- Intake filter / noise silencers
- Metal belt guards, copper discharge & unloader tubing, oil sight glass
- (Factory-mounted options available — low oil control, hour meter, alternator, electronic auto drain, dual control, intake silencers, belt tensioner, aftercooler. Contact us to configure.)
Manuals & Documentation