Castair 8P150B — 8 Gallon Belt Drive Portable Air Receiver Tank, 150 PSI
The Castair 8P150B is the belt drive version of Cast Air's 8-gallon portable air receiver tank. It shares the same 10x24" cylinder and 150 PSI rating as the direct drive model, but the top plate is a 6x16" format — the wider footprint that belt drive compressor assemblies require. If you are building or rebuilding a belt drive portable compressor, this is the correct tank.
At $145.22, the 8P150B costs a bit more than the direct drive 8P150D ($106.26), and the weight difference reflects the larger top plate and additional hardware: 35 lbs versus 30 lbs. Both are the right tank for their respective drive type — the distinction is purely about which motor-pump arrangement you are running.
Tank Specifications
- Part Number: 8P150B
- Capacity: 8 gallons
- Dimensions: 10" diameter x 24" length
- Top Plate: 6" x 16" — sized for belt drive (BD) motor-pump mounting
- Maximum Working Pressure: 150 PSI
- Weight: 35 lbs
- Price: $145.22
- Configuration: Portable (horizontal orientation, designed for wheeled cart or frame)
- ASME Code: Non-code (appropriate for portable compressor units at this pressure and volume)
Why Belt Drive Needs a Bigger Top Plate
On a belt drive compressor, the motor does not mount directly over the pump. Instead, the motor sits offset from the pump, connected by a V-belt that drives a pulley on the crank. This arrangement puts the motor and the pump side by side on the top plate rather than stacked. The 6x16" top plate on the 8P150B gives you the length to bolt down both the motor and the pump head at the correct center-to-center distance for the belt alignment.
On a direct drive unit, the motor bolts straight onto the pump crank — the whole assembly is compact and the 6x7" top plate on the 8P150D is sufficient. Order the wrong tank and the mounting holes will not match. Confirm your drive type before you order.
Belt Drive Advantages at This Tank Size
Belt drive compressors run the pump at a lower RPM than direct drive units, typically using a smaller motor pulley driving a larger pump pulley. The slower pump RPM means:
- Lower operating temperature — easier on rings, valves, and oil
- Longer pump service life between rebuilds
- Generally quieter operation than direct drive at equivalent output
- More serviceability — the belt is a maintenance item you can replace without pulling the pump
The tradeoff is that belt drive compressors are physically larger and slightly heavier for the same air output. For a shop owner who wants a portable unit that holds up over years of daily use, belt drive is often the better long-term investment even in the 8-gallon class.
8 Gallons of Capacity in Practice
Eight gallons handles intermittent pneumatic tool use well — framing nailers, finish nailers, brad guns, blow guns, and tire inflation. For sustained-draw tools like impact wrenches, die grinders, or sand blasters, the compressor will cycle frequently at this tank size. That is appropriate for the portable class.
If you need more capacity without going stationary, Cast Air's 20-gallon portable (20P150C complete kit) is the next step up. For most portable applications, the 8-gallon belt drive is a proven, reliable size.
Tank Only vs. Complete Kit
The 8P150B is the tank-only purchase. Cast Air also offers the 8P150BC complete kit, which includes the tank plus wheels, axle, handle, vibration pads, and belt guard — everything needed to complete the portable assembly, with approximately 15% savings over sourcing the components separately.
Order the 8P150B (tank only) if:
- You are replacing only the tank on an existing belt drive portable
- You already have the wheel and axle hardware from a previous build
- You have a custom cart or mounting arrangement planned
Order the 8P150BC (complete kit) if:
- You are building a new belt drive portable compressor from scratch
- You want one part number for the full portable assembly with casters
- You want the 15% kit savings on the wheels, axle, handle, and belt guard
Accessories Available Separately
If you need individual hardware components, Cast Air offers:
- W7.5x1.5x.5: 7.5" wheel with 1/2" bore
- W10x1.5x.5: 10" x 1.5" wheel with 1/2" bore
- W10x3x.75: 10" x 3" wheel with 3/4" bore
- AB12: Axle bolt 1/2" for 8-gallon portable
Non-Code Classification
The 8P150B carries a non-code rating. For portable compressor tanks at 150 PSI in the 8-gallon size class, ASME code certification is not required by most regulatory agencies. Cast Air builds these tanks to the quality standard appropriate for their rated service pressure. If your installation requires ASME-coded tanks — a permanent shop air system in a jurisdiction that mandates it, for example — Cast Air manufactures coded vessels in larger sizes. For portable compressor use, non-code is standard and correct.
Why Buy From Air Compressor Factory Direct?
- Specialist supplier: We carry Cast Air OEM tanks sourced directly from the manufacturer in Minnesota. No generic substitutes, no mismatched drill patterns.
- Free shipping on qualifying orders
- Free technical support: Call 866-217-0063. If you are not sure whether you need the belt drive 8P150B or the direct drive 8P150D, or whether the tank-only or complete kit makes more sense for your build, we can work through it with you.
- Full manufacturer warranty on all Cast Air tanks
- Honest guidance: If the 8-gallon is not the right size for your application, we will tell you what is.
Call 866-217-0063 for quick answers and help!
