The Castair D1518P20 is a 1.5 HP, single-stage, oil-lubricated portable air compressor in the Contractor Series — an 8-gallon unit built for job sites, small shops, and contractor use where you need reliable compressed air without committing to a full floor compressor. This is not a high-volume production machine. It runs at 1725 RPM direct drive, puts out 9.9 CFM at 0 PSI and 4.6 CFM at 100 PSI, and tops out at 125 PSI. For running air tools, blow guns, and light pneumatic work on 115V standard household current, it does the job with a cast iron pump that will outlast oil-less alternatives by a wide margin.
Castair has been building compressors in Spicer, Minnesota since 1991 — family owned and operated. The Contractor Series uses a cast iron sleeve pump, the right choice if longevity matters. Oil-less compressors are cheaper to manufacture and louder in use; oil-lubricated cast iron pumps at the right RPM outlast them by up to 10x.
Key Features
Pump and Motor Construction
- Cast Iron Sleeve Pump: Oil-lubricated cast iron cylinder — up to 10 times the service life of oil-less units under comparable use
- Direct Drive Motor: 1.5 HP, 115V single-phase, 12 amps, 1725 RPM — runs on a standard 15-amp circuit, no special wiring needed
- Fan Cooled with Thermal Overload Protection: Motor shuts down on overheat rather than burning out — important for job site use where ambient temperatures vary
- Two-Piece Connecting Rod: Independent wrist pin with a real three-ring piston — not a simplified one-piece design; built for service life and serviceability
- Finned Copper Discharge Tube: Dissipates heat from compressed air before it enters the tank, reducing moisture buildup and thermal stress on the pump head
Tank and Safety Equipment
- 8-Gallon Portable Tank: Compact at 24" L x 14" W x 25" H and 75 lbs shipped weight — manageable for job site transport
- 125 PSI Maximum Pressure: Standard single-stage pressure rating — covers most pneumatic hand tools and accessories
- ASME Safety Valve Installed: Note per Castair spec: 8-gallon single tank units are non-ASME certified, but ship with an ASME-rated safety valve
- Heavy Duty Pressure Switch: On/off control with copper bleeder tube — the bleeder allows the pump to restart unloaded rather than fighting trapped pressure in the head
Air Quality and Convenience Features
- Filter/Silencers: Intake filter/silencer provides cleaner air and reduces operating noise compared to open-intake designs
- Regulator with Gauge and Quick Coupler: Factory mounted — regulated output ready to connect your air hose directly
What's in the Box
- Castair D1518P20 air compressor (motor, pump, tank — fully assembled)
- Regulator with pressure gauge (factory mounted)
- Quick coupler (factory mounted at regulated outlet)
- ASME safety valve (factory installed)
- Owner's manual
Air hose and tools are not included. Unit ships assembled and ready to operate.
Available Configurations — Where This Fits in the Castair Lineup
The D1518P20 is the entry-level portable in the Castair Contractor Series. Here is how it compares to what is available if your needs change:
- D1518P20 (this unit) — 1.5 HP / 8 gal / 115V / 4.6 CFM @ 100 PSI: Portable job site and small shop use, single tool, standard outlet
- Castair Industrial Series (single-stage and two-stage): Larger floor units, higher CFM, 120-200 gallon tanks, dedicated shop installations
- Castair Duplex Series (10–30 HP): Two-pump systems with 35–123 CFM and built-in backup redundancy for production shops that cannot afford downtime
When Does a Shop Need This vs. Stepping Up?
The D1518P20 fits when:
- You need portable air at a job site or secondary location where a floor compressor is impractical
- You run one air tool at a time — impact wrench, blow gun, air ratchet — not continuous-duty tools
- You have 115V standard outlet power only
- You want an oil-lubricated pump for longevity rather than a cheap oil-less unit that degrades quickly
Step up to the Industrial or Duplex Series when:
- You run spray guns, sand blasters, or any continuous-duty tool requiring sustained CFM
- More than one technician needs air simultaneously
- Your shop requires 175 PSI two-stage pressure for higher-demand applications
- Compressed air is a primary shop utility, not occasional supplemental use
Technical Specifications
- Model Number: D1518P20
- Series: Contractor Series
- Horsepower: 1.5 HP
- Voltage / Phase / Amps: 115V / 1-Phase / 12A
- Pump Type: Single-stage, direct drive, oil-lubricated, cast iron sleeve
- Pump RPM: 1725
- CFM @ 0 PSI: 9.9
- CFM @ 100 PSI: 4.6
- Maximum Pressure: 125 PSI
- Tank Capacity: 8 gallons
- Tank Style: Portable horizontal
- Dimensions (L x W x H): 24" x 14" x 25"
- Shipped Weight: 75 lbs
- ASME Certification: Non-ASME tank (8-gal single per Castair spec); ASME safety valve installed
Why Buy From Air Compressor Factory Direct?
We have specialized in professional-grade shop compressors and pneumatic equipment since 2016. When you call, you reach someone who can explain the difference between Castair's C1, C2, and C3 pump configurations, help you size a duplex system for your shop's actual CFM demand, and give you a straight answer on whether this unit fits your needs or whether you need more machine. We do not push product just to move inventory.
- Free Shipping on qualifying orders to the contiguous US
- Free Technical Support — call 866-217-0063 and talk to someone who knows compressors
- Full Manufacturer Warranty — Castair backs their equipment; we support it from our end
- Honest Guidance — if this unit does not fit your shop, we will tell you before you order
Call 866-217-0063 for quick answers and help!
