Cast Air Heavy Duty Shop Tandem Air Compressor — T15312HC2-S
The T15312HC2-S runs two 15 HP motors at 795 RPM — the slower, larger HC2 pump configuration — on a 120-gallon horizontal ASME tank. Combined output is 123.4 CFM at 0 PSI and 100.4 CFM at 175 PSI. At $7,639, this is the higher-CFM choice in the 15 HP tandem lineup on a 120-gallon tank. The HC2 pump runs slower than the HC1 (795 RPM vs. 898 RPM), which means less heat, quieter operation, and longer pump life — and more CFM per displacement because the pump is physically larger. If your shop consistently runs close to its air capacity limit, the HC2 configuration is the one to buy.
HC1 vs. HC2 — What Does It Mean?
- HC1 (898 RPM): Standard Cast Air pump at a moderate speed. Good for shops with intermittent peak demand and adequate recovery time. 110 CFM combined on the 15 HP tandem.
- HC2 (795 RPM): Larger cast iron pump running at a slower RPM. More CFM (123.4 combined), quieter operation, longer pump life between rebuilds. The HC2 is what you want when the compressor is running hard most of the day.
- Rule of thumb: If you expect the compressor to be cycling more than 60–70% of the time, the HC2 pays for itself in reduced maintenance intervals and lower operating noise.
Cast Iron Pump Features
- All cast iron construction: Cylinders, heads, and crankcase. Cast iron handles heat and pressure cycles that aluminum cannot sustain over tens of thousands of hours.
- 795 RPM pump speed: Slow RPM is the core of Cast Air's design philosophy. The HC2 pump runs at 795 RPM — quiet enough to have a conversation near the compressor room, unlike the shrieking import units.
- Tapered roller bearings: Both ends of the crankshaft. Superior to ball bearings for radial and axial load at sustained compressor duty.
- Precision steel connecting rods: Automotive-type rod insert bearings at the crankshaft, needle bearings at the wrist pin.
- Disc and spring valves: The highest-wear item in any piston compressor. Cast Air's disc/spring valves are easy to inspect and rebuild in the field.
- 4-ring pistons: Better ring seal, higher efficiency, less oil carry-over.
- Centrifugal unloader: Loadless start on every cycle. Extends motor and pressure switch life significantly over hard-start designs.
Tank and Controls
- 120-gallon horizontal ASME tank: Powder-coated, channel base. Right-sized for the HC2 pump's recovery rate — the faster CFM output means this tank stays charged under most shop demand patterns.
- Two magnetic motor starters — mounted and wired: Factory-installed. Connect to 3-phase service and operate.
- ASME safety valves: Factory-set on both sides.
- Metal belt guards: Fully enclosed on both assemblies.
- Copper discharge and unloader tubes: Copper throughout — no rubber hose on the hot side.
- 1,725 RPM industrial motors: 15% service factor or higher.
Available Factory-Mounted Options
- Low Oil Control (#6304x2M): Auto-shutdown on low oil for both pumps.
- Hour Meter 230V (#HRM75x2M) or 460V (#HRM460x2M): Track runtime independently on each pump.
- Alternator Relay (#ALT230M or #ALT460M): Alternates lead pump automatically each cycle.
- Electronic Auto Drain (#SDV03M): Timed solenoid condensate drain.
- Dual Control (#DC2x2M): Start/stop and throttle control modes.
- Intake Noise Silencers (#SA100x4M): Reduces intake noise on both pumps.
- Belt Tensioner (#254Dx2M for 15 HP): Self-tensioning motor base.
- Aftercooler (#BGAC1x2M, 70 CFM rated): Belt-guard-mounted aftercooler for both sides.
- All Options Package (#AOC2D): All asterisk options bundled at 10% discount.
What Is in the Box
- Two cast iron two-stage HC2 pump and motor assemblies on a single rigid frame
- 120-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 — 15 HP Shop Tandem Lineup
- T15312HC1-S: 2×15 HP, 898 RPM, 110 CFM / 90.6 CFM @ 175 PSI, 120-gal — $6,675
- T15312HC2-S: 2×15 HP, 795 RPM, 123.4 CFM / 100.4 CFM @ 175 PSI, 120-gal — $7,639 (this unit)
- T15324HC1-S: 2×15 HP, 898 RPM, 110 CFM / 90.6 CFM @ 175 PSI, 240-gal — $8,121
- T15324HC2-S: 2×15 HP, 795 RPM, 123.4 CFM / 100.4 CFM @ 175 PSI, 240-gal — $9,173
When Does a Shop Need This vs. Stepping Up or Down?
- Step down to HC1: If your demand peaks are short and there is recovery time between bursts, the HC1 at $6,675 does the job. The HC2 is worth the extra $964 when the compressor is running most of the day.
- This unit is right when: You have a 4–8 bay shop running simultaneously, or you are in a body shop environment where painters and prep technicians overlap. 100+ CFM at 175 PSI sustained output keeps tools performing at rated pressure across multiple drops.
- Step up to 240-gallon: If your demand spikes are intense but short — a blast room, a tire inflation station that cycles hard — the T15324HC2-S adds 120 gallons of receiver storage for $1,534 more.
- Step up to 20 HP tandem: If you consistently need more than 100 CFM and run at or above this unit's capacity, the T20312HC2-S adds 180 CFM on the same 120-gallon tank footprint for $7,974.
Technical Specifications — T15312HC2-S
- Model Number: T15312HC2-S
- Horsepower: 2 × 15 HP (30 HP total)
- Phase: 3-phase
- Pump RPM: 795 (HC2 configuration)
- CFM @ 0 PSI: 123.4 (combined, both pumps)
- CFM @ 175 PSI: 100.4 (combined, both pumps)
- Tank Capacity: 120 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: $7,638.70
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. When you call us about a Cast Air Shop Tandem, you get a straight answer about whether the HC1 or HC2 pump, and whether the 120 or 240-gallon tank, is right for your actual CFM demand — not a pitch to sell you the most expensive unit.
- Free shipping to a commercial address with a loading dock or forklift
- Free tech support at 866-217-0063 — before and after the sale
- Full Cast Air manufacturer warranty — handled directly through us
- Honest upgrade guidance: If this unit is more than you need, we will tell you.
Call 866-217-0063 for quick answers and help!
