Cast Air Heavy Duty Shop Tandem Air Compressor — T20324HC2-S
The T20324HC2-S runs two 20 HP motors with HC2 cast iron pumps at 758 RPM on a 240-gallon horizontal ASME tank. Combined output is 180 CFM at 0 PSI and 140 CFM at 175 PSI. At $9,460, this is the 240-gallon version of the 20 HP HC2 tandem — same pump output as the T20312HC2-S, but with double the receiver storage. The 240-gallon tank is the right specification when your shop has intense peak demand: blast equipment, multiple spray guns firing simultaneously, tire inflation runs, or production machinery cycling on and off. The larger receiver absorbs those spikes and keeps system pressure stable so tools perform at rated capacity throughout the cycle.
Why 240 Gallons on a 20 HP Tandem?
- More buffer for demand spikes: At 175 PSI, a 240-gallon ASME tank stores approximately twice the air energy of a 120-gallon tank. When multiple high-demand tools fire simultaneously, the 240-gallon receiver delays pressure drop while the pumps catch up.
- Fewer pump cycles: More storage means the pumps start and stop less frequently. Fewer cycles means less wear on pressure switches, motor contactors, and unloaders over time.
- Steady pressure for precision work: Spray work, torque-sensitive air tools, and pneumatic fixtures perform better when system pressure stays consistent. The 240-gallon tank provides that stability.
Cast Iron Pump Features
- All cast iron construction: Both pump cylinders, heads, and crankcases are cast iron. Thermal stability for sustained output at 20 HP per side.
- 758 RPM (HC2 configuration): Moderate slow-speed operation. Quieter and cooler than high-speed import equipment. Long intervals between valve and ring service.
- Tapered roller bearings: Both crankshaft ends on both pumps. Superior load handling for production-level duty.
- Precision steel connecting rods: Automotive-type rod bearings at the crank, needle bearings at the wrist pin.
- Disc and spring valves: Field-serviceable. The most common wear item in any piston compressor — Cast Air's design makes them easy to inspect and rebuild without specialized tooling.
- 4-ring pistons: Higher efficiency and less oil in the discharge stream compared to 2-ring designs.
- Centrifugal unloader: Loadless start every cycle. Critical at 40 HP total — the unloader prevents the high inrush current that degrades motor insulation and contactors over time.
Tank and Controls
- 240-gallon horizontal ASME tank: Powder-coated, channel base. The 240-gallon receiver paired with 140 CFM of pump output gives this machine excellent pressure recovery and stability under variable demand.
- Two magnetic motor starters — mounted and wired: Factory-installed on both pump sides. Connect to 3-phase service and operate.
- ASME safety valves: Factory-set on both sides.
- Metal belt guards: Fully enclosed on both pump assemblies.
- Copper discharge and unloader tubes: Copper throughout the hot side of both assemblies.
- 1,725 RPM industrial motors: 15% service factor or higher on both 20 HP motors.
Available Factory-Mounted Options
- Low Oil Control (#6304x2M): Automatic oil-level shutdown on both pumps.
- Hour Meter 230V (#HRM75x2M) or 460V (#HRM460x2M): Independent runtime tracking on each pump.
- Alternator Relay (#ALT230M or #ALT460M): Automatically alternates lead pump each cycle to equalize wear.
- Electronic Auto Drain (#SDV03M): Timed solenoid condensate drain. Even more important on the 240-gallon tank where condensate accumulates in a larger volume.
- Dual Control (#DC2x2M): Start/stop and throttle control modes.
- Intake Noise Silencers (#SA100x4M): Reduces intake noise on both pumps.
- Aftercooler (#BGAC1x2M, 70 CFM rated per unit): Belt-guard-mounted aftercooler on both pump sides.
- All Options Package (#AOC2D): All asterisk options at 10% off combined price.
What Is in the Box
- Two cast iron two-stage HC2 pump and motor assemblies (20 HP each) on a single rigid frame
- 240-gallon horizontal powder-coated ASME tank with channel base
- Two magnetic motor starters, mounted and wired at the factory
- Two ASME safety valves
- Two metal belt guards (fully enclosed)
- Copper discharge and unloader tubes on both sides
- Pressure switch for each pump
Optional accessories are factory-installed at time of order and are not included unless specified at purchase.
Available Configurations — 20 HP Shop Tandem Lineup
- T20312HC2-S: 2×20 HP, 758 RPM, 180 CFM / 140 CFM @ 175 PSI, 120-gal — $7,974
- T20312HC3-S: 2×20 HP, 570 RPM, 180 CFM / 140 CFM @ 175 PSI, 120-gal — $10,285
- T20324HC2-S: 2×20 HP, 758 RPM, 180 CFM / 140 CFM @ 175 PSI, 240-gal — $9,460 (this unit)
- T20324HC3-S: 2×20 HP, 570 RPM, 180 CFM / 140 CFM @ 175 PSI, 240-gal — $11,610
When Does a Shop Need This vs. Stepping Up or Down?
- Step down to 120-gallon (T20312HC2-S): If your demand is relatively steady and your tools do not all fire simultaneously, the 120-gallon tank at $7,974 saves $1,486. The pump output is identical — the only difference is storage volume.
- This unit is right when: Your shop has real demand spikes — moments when every tool is running at once — and you want the system to absorb those spikes without a pressure drop that affects tool performance or spray quality.
- Step up to HC3: If the compressor runs all day continuously, the T20324HC3-S at $11,610 offers the HC3 pump's 570 RPM operating speed and extended service life. The additional $2,150 over this unit is worth it for operations with 8–10+ hours per day of heavy compressor use.
Technical Specifications — T20324HC2-S
- Model Number: T20324HC2-S
- Horsepower: 2 × 20 HP (40 HP total)
- Phase: 3-phase
- Pump RPM: 758 (HC2 configuration)
- CFM @ 0 PSI: 180 (combined, both pumps)
- CFM @ 175 PSI: 140 (combined, both pumps)
- Tank Capacity: 240 gallons, horizontal
- Tank Type: ASME-certified, powder-coated, channel base
- Motor Speed: 1,725 RPM, 15% service factor
- Pump Type: Two-stage, all cast iron, centrifugal unloader
- Controls: Two magnetic motor starters, mounted and wired
- Discharge Tubing: Copper
- Belt Guard: Metal, fully enclosed
- Price: $9,460.25
Note: Exact LxWxH dimensions and shipping weight for this configuration are not individually published by Castair. Contact us for freight details before ordering.
Why Buy From Air Compressor Factory Direct?
We have specialized in industrial air compressor sales since 2016. At the 20 HP tandem level, we can help you sort out whether HC2 or HC3, and whether 120 or 240-gallon, is the right call for your specific operation — before you spend $9,000–$11,000 on the wrong configuration.
- Free shipping to a commercial address with a loading dock or forklift
- Free tech support at 866-217-0063 — we will size this correctly for your actual demand
- Full Cast Air manufacturer warranty — handled directly through us
- Honest guidance: If you would be better served by a different configuration, we will tell you.
Call 866-217-0063 for quick answers and help!
