Castair 5HP 1-Phase Rotary Screw 80 Gallon Vertical G11 Air End — R518VG11
The Castair R518VG11 is a 5-horsepower, single-phase, 80-gallon vertical rotary screw air compressor equipped with the G11 air end — Castair's heavy-duty screw element for this horsepower range. Single-phase 230V power makes this unit accessible to shops without 3-phase service. The G11 air end designation identifies the specific rotary screw element used, which affects maintenance kit selection (MKG11 is the corresponding PM kit). At 5HP rotary screw output, expect approximately 20 CFM at 100 PSI, 100% duty cycle, and the consistent quiet output that separates rotary screw from piston in a production shop environment.
Note: Exact CFM, weight, and dimensions for the G11 variant are based on Castair's rotary screw product line conventions. The P75 air end models (R518VP75) are confirmed at 20 CFM @ 100 PSI, 70" height, 480 lbs. Contact 866-217-0063 to confirm G11 variant specs before ordering.
G11 Air End — What This Means for Maintenance
- Air end identification: Castair uses different rotary screw elements across their product line. The G11 designation identifies the specific screw element, which determines which filters and maintenance kit apply.
- G11 maintenance kit: Part number MKG11 — covers 5-15HP units with G11 air end. Includes 2 air filters, 4 oil filters, 1 separator filter, and 5 gallons of Cast-Lube synthetic oil at a 10% discount versus individual pricing.
- G11 air filter: Part RAFG11 — paper element, ID: 2-5/8", OD: 3-7/8", height: 3-1/8". Stock these on the shelf.
- G11 oil filter: Part ROFD3-4-G11 — spin-on, same as the D3, D31, and D4 air ends. Widely available.
- G11 separator filter: Part RSFD3-4-6-G11-P75 — covers G11 and other common Castair air ends.
Vertical Tank — Layout and Installation
- Dimensions: 34 × 26 × 70" (L×W×H)
- Small floor footprint: The vertical tank takes up a 34×26-inch floor area, less than 6 square feet. Fits neatly against a wall.
- Taller profile: 70-inch height requires adequate ceiling clearance. Standard 8-foot ceilings are fine. Lower ceilings may require the horizontal version (R518HG11).
- Alternative orientation: R518HG11 (horizontal) is the same unit in horizontal configuration. Same output, different footprint.
5HP Rotary Screw Output — Real Shop Capacity
- Expected: approximately 20 CFM at 100 PSI
- 1/2-inch impact: 4-8 CFM — two running simultaneously, comfortable
- 3/8-inch air ratchet: 4-6 CFM — multiple tools at once
- DA sander: 12-20 CFM — one sander at a time
- HVLP spray gun: 9-14 CFM — painting with one gun
- 1-inch impact: 10-25 CFM — fine for intermittent use; continuous heavy use should step up to 7.5HP
Castair Build Quality
- 100% duty cycle: Rotary screw design runs continuously without piston-style thermal limitations.
- All cast iron construction: Castair builds with cast iron throughout — pumps, heads, all primary components. Not aluminum.
- Industrial 1725 RPM motor, full 15% service factor: Commercial grade. Runs cool, handles occasional peak loads.
- Single solenoid air end control: No computers. No lockout codes. Field-repairable with standard parts.
- Analog pressure and temperature gauges standard: Read at a glance without navigating menus.
- High pressure and dual high temperature shutdown standard: Built-in protection. Not an option.
- Factory-filled with Cast-Lube synthetic oil: 4,000-hour or one-year change interval.
- Built-in air/oil separator with spin-on filter: Keeps oil out of compressed air. Standard spin-on format.
- Off-shelf V-belts with adjustable tensioner: Available at any industrial supply.
- Air/oil lines in copper pipe: Heat and vibration resistant. Standard fittings.
- Air-cooled aftercooler/oil cooler standard: Removable for cleaning.
- Hour meter standard: Track actual run hours.
- 10-minute auto shutdown timer: Electricity savings when air demand stops.
- ASME-rated 80-gallon tank: Code-compliant for commercial installation.
- Pre-wired magnetic starter: Connect 230V single-phase incoming power.
- Pressure options: 135 PSI standard, 150 or 175 PSI available.
- 2-year warranty on air end, electric motor, and tank
Available Configurations — 5HP 1-Phase Lineup
- R518VG11 (this unit): 5HP, 1-Phase, 80 Gal Vertical, G11 air end
- R518HG11 (horizontal): Same specs, horizontal tank
- R518VP75: 5HP, 1-Phase, 80 Gal Vertical, P75 air end — 20 CFM @ 100 PSI — 34 × 26 × 70" — 480 lbs
- R538VP75: 5HP, 3-Phase 230V, 80 Gal Vertical — 20 CFM @ 100 PSI — 470 lbs
- R718VP75: 7.5HP, 1-Phase, 80 Gal Vertical — 31 CFM @ 100 PSI — 555 lbs
When Does a Shop Need This vs. Stepping Up or Down?
- Right for: Single-phase shop, 1-2 bays, steady air tool use through the day. The rotary screw never needs to rest, so one tech running tools continuously is well within spec.
- Step up to 7.5HP if: Multiple techs running air tools at the same time. 31 CFM @ 100 PSI handles the overlap without pressure drop.
- Choose 3-phase if: Your facility has 3-phase service. The 3-phase motor draws less amperage per leg and starts smoother.
- G11 vs. P75 air end: Both deliver the same 5HP output. The difference is the internal screw element and the corresponding maintenance parts. Confirm which model you're ordering before purchasing PM kits.
Technical Specifications
- Model: R518VG11
- Horsepower: 5 HP
- Phase: 1-Phase
- Voltage: 230V single-phase
- Tank: 80 gallon, vertical, ASME-rated
- Air End: G11
- Expected CFM @ 100 PSI: Approximately 20 (confirm with Castair)
- Dimensions (L×W×H): 34 × 26 × 70"
- Compressor Type: Rotary screw
- Duty Cycle: 100%
- Standard Pressure: 135 PSI (150 or 175 PSI optional)
- Motor Speed: 1725 RPM industrial, full 15% service factor
- Drive: Belt drive, off-shelf V-belts with adjustable tensioner
- Lubrication: Oil-injected, Cast-Lube synthetic, 4,000-hour/1-year interval
- Controls: Single solenoid, pre-wired magnetic starter, analog gauges, hour meter, 10-minute auto shutdown
- Shutdowns: High pressure, dual high temperature (standard)
- Maintenance Kit: MKG11
- Warranty: 2-year on air end, electric motor, and tank
- Manufacturer: Castair, Inc. (Spicer, Minnesota)
What's in the Box
- Castair rotary screw compressor with G11 air end, mounted on 80-gallon vertical ASME tank
- Pre-wired magnetic starter and controls
- Air/oil separator with spin-on filter
- Air-cooled aftercooler/oil cooler
- Hour meter
- Pre-filled with Cast-Lube synthetic oil
- Analog pressure and temperature gauges
Why Buy From Air Compressor Factory Direct?
- Castair specialist: We know the G11 vs P75 air end difference and can make sure you order the right PM kit from the start
- Free shipping on qualifying orders
- Free technical support: Call 866-217-0063 — we stock and support the full Castair line
- Full manufacturer warranty honored and supported
- Honest guidance: If the 7.5HP unit is what your shop actually needs, we'll tell you
Call 866-217-0063 for quick answers and help!
