Cast Air Heavy Duty Shop Tandem Air Compressor — T15312HC1-S
The T15312HC1-S is a two-stage twin-pump tandem from Cast Air running two 15 HP motors on 3-phase power, paired with a 120-gallon horizontal ASME tank. The HC1 configuration runs the cast iron pumps at 898 RPM, producing 110 CFM at 0 PSI and 90.6 CFM at 175 PSI from both pumps combined. At $6,675, this is the entry point into the 15 HP tandem lineup — the 120-gallon tank keeps the footprint manageable while still giving you enough receiver volume to handle peak air demand in a busy shop. If you are running tire mounting equipment, paint prep tools, or multiple air-powered lifts simultaneously, this configuration gives you the CFM without the premium of the larger tank or slower-RPM HC2 pump.
Why Two Pumps?
- Redundancy: One pump down does not shut down the shop. Service the failed side while the working pump carries the load.
- Load sharing: Two 15 HP pumps sharing demand run cooler than one 30 HP unit under the same total load.
- Alternator option: Add the ALT230M or ALT460M relay and the system automatically alternates which pump leads each cycle, keeping runtime hours equal on both sides.
Cast Iron Pump Features
- All cast iron pump construction: Cylinders, heads, and crankcase are cast iron for thermal stability and long service life.
- 898 RPM (HC1 configuration): The HC1 pump runs at a higher RPM than the HC2 — more CFM per pump size, but still dramatically slower than the 1,200–1,800 RPM pumps found in import equipment.
- Tapered roller bearings: Both ends of the crankshaft use tapered roller bearings for superior crankshaft support and reduced friction.
- Precision steel connecting rods: Automotive-type insert bearings at the crankshaft, needle bearings at the wrist pin.
- Disc and spring valves: Serviceable in the field. More reliable than reed valves and easier to rebuild.
- 4-ring pistons: Higher efficiency, less oil carry-over into the discharge air.
- Centrifugal unloader: Loadless start every time. The unloader bleeds head pressure before startup, protecting motors and pressure switches from hard starts.
Tank and Controls
- 120-gallon horizontal ASME tank: Powder-coated, channel base. The 120-gallon tank is the right size when shop footprint matters and your demand spikes are short — the two pumps recover quickly enough that 120 gallons is adequate for most shop workflows.
- Two magnetic motor starters — mounted and wired: Factory-installed on both pump sides. Connect to your 3-phase panel and operate.
- ASME safety valves: Set to factory-spec relief pressure on both sides.
- Metal belt guards: Fully enclosed on both pump assemblies.
- Copper discharge and unloader tubes: Heat-resistant copper tubing, not rubber hose.
- 1,725 RPM industrial motors: Full 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 on each pump independently.
- Alternator Relay (#ALT230M or #ALT460M): Automatically alternates lead pump each cycle.
- Electronic Auto Drain (#SDV03M): Timed solenoid condensate drain.
- Dual Control (#DC1x2M): Start/stop and throttle control modes (HC1 units use DC1 designation).
- 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 pump sides.
- All Options Package (#AOC1D): Order all asterisk options together and receive 10% off.
What Is in the Box
- Two cast iron two-stage 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 (this unit)
- T15312HC2-S: 2×15 HP, 795 RPM, 123.4 CFM / 100.4 CFM @ 175 PSI, 120-gal — $7,639 (larger pump, more CFM)
- T15324HC1-S: 2×15 HP, 898 RPM, 110 CFM / 90.6 CFM @ 175 PSI, 240-gal — $8,121 (larger tank for bigger demand spikes)
- T15324HC2-S: 2×15 HP, 795 RPM, 123.4 CFM / 100.4 CFM @ 175 PSI, 240-gal — $9,173 (maximum 15 HP configuration)
The HC1 configuration gives you 898 RPM pump speed and 110 CFM combined — the HC2 steps up to 795 RPM (slower, quieter, longer life) and 123.4 CFM. If your shop consistently runs at or near capacity, the HC2 is worth the additional cost. If you have shorter peaks with recovery time, the HC1 on a 120-gallon tank handles it for less money.
When Does a Shop Need This vs. Stepping Up or Down?
- Step down: If your shop runs two or three air tools at once and your current 7.5 HP compressor keeps up most of the time, you do not need a 15 HP tandem. A single 10 HP or 15 HP industrial unit handles that load with less capital cost.
- This unit is right when: You are running a 4–6 bay shop where multiple technicians use air tools simultaneously, or a tire shop with mounting and balancing equipment plus impact guns going at once. The 90.6 CFM at 175 PSI sustained output means your system pressure stays stable while every bay is working.
- Step up: Body shops running full spray booths, shops with dedicated CNC air-powered equipment, or operations needing 100+ CFM continuously should look at the 20–30 HP tandem models or Cast Air's rotary screw line.
Technical Specifications — T15312HC1-S
- Model Number: T15312HC1-S
- Horsepower: 2 × 15 HP (30 HP total)
- Phase: 3-phase
- Pump RPM: 898 (HC1 configuration)
- CFM @ 0 PSI: 110 (combined, both pumps)
- CFM @ 175 PSI: 90.6 (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: $6,674.80
Note: Exact LxWxH dimensions and shipping weight for this tandem configuration are not published individually 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. Cast Air's American-built, cast iron machines are a core part of our lineup because they hold up where import equipment fails. When you buy through us:
- Free shipping to a commercial address with a loading dock or forklift
- Free tech support at 866-217-0063 — we will help you choose between HC1 and HC2, and between the 120 and 240-gallon tank, based on your actual shop CFM demand
- Full Cast Air manufacturer warranty — we handle warranty claims directly with Cast Air on your behalf
- Honest upgrade guidance: We will tell you if a different configuration fits your shop better. We would rather sell you the right machine than the wrong one.
Call 866-217-0063 for quick answers and help!
