Quincy 451CS80VCB QT Pro — 5 HP, 80-Gallon Two-Stage Compressor on Ordinary Single-Phase Power

Nearly every 80-gallon two-stage compressor in this size class is a three-phase machine, and that single detail is what stops most of them going into an independent shop or a serious home garage. The 451CS80VCB is the exception in its own family: it is wound for 230 Volt, 1-Phase supply, and its magnetic starter is fitted at the factory rather than sold as a separate box you have to specify and mount yourself.

Read those two facts together and you have the reason to buy this particular model over its siblings. No rotary phase converter. No sourcing switchgear. The supply most workshop buildings already carry is enough, and the contactor and thermal overload that protect a 5 HP motor are already on the machine when it comes off the pallet.

What single-phase actually buys you

A phase converter is another machine to buy, site, and eventually repair. Skipping it is worth real money and real floor space. The trade sits on the supply side: a 5 HP single-phase motor pulls a heavier starting current than the same horsepower spread across three phases, so the circuit feeding it has to be sized properly and the panel has to have room for it. Give your electrician the three figures that define the load — 5 HP, 230 Volt, 1-Phase — and let them size the circuit for your run length and local code. Ask us and we will put the manufacturer's current figure in writing.

The starter, and why it is not a trim item

A magnetic starter does two jobs on a motor this size. It switches the heavy current through a contactor instead of making a pressure switch do work it was never designed to do, and it carries a thermal overload that drops the motor out before a struggling machine cooks its own windings. On compressors sold without one, that is a purchase, a mounting job and an electrician's visit that most listings never mention. On this one it is already done.

Will it fit?

The tank stands upright, which is the layout to choose when floor space is the constraint rather than ceiling height. The machine occupies roughly 37" by 24" of floor and stands 74" tall, so measure the height of your intended corner — including any shelf, roller-door track or ductwork above it — before the truck arrives, and leave working room around the belt guard, the sight glass and the drain.

The floor matters as much as the ceiling. This is 680 lbs concentrated on a small footprint, and a tall tank on an uneven or soft slab will work its mounts loose over a season and transmit far more vibration into the building than it should. A flat, solid, level pad is a customer responsibility and it is the least expensive reliability you can buy.

Plan the air line too. The tank outlet is 3/4", and there is no aftercooler or air dryer on this machine, so if your work needs dry air the drying and filtration are separate items in the run.

Continuous duty, and what the two stages are for

This pump is rated for a 100% duty cycle. That is not shorthand for "powerful"; it means the machine is built to keep pumping rather than being scheduled around a cool-down. Splash lubrication, a cast-iron cylinder pair and a large balanced flywheel angled to move air across the pump are what make that claim survivable, and the industrial-class bearings decide how long the pistons stay round.

Two-stage compression is the other half. Air is compressed once, passed through a high-efficiency finned tube intercooler, then compressed again. Cooling the charge between stages is why the machine holds 175 PSI as a working condition instead of a strained maximum, and why carbon does not build up in the head the way it does on a single-stage pump run hard. Cooler air means longer valve life, and valves usually decide when a pump stops being efficient. The head is aluminium for heat dissipation and the reed valves are stainless steel — a corrosion decision as much as a flow one, because a compressor makes water every day of its life. Quincy states the pump is designed for over 50,000 hours of service and that the unit is built in the U.S.A.

About the delivered-air figure

We are not going to headline a flow rating for this model. Our specification block records the pump at 17.2 cubic feet per minute rated at 175 PSI, but that value reaches us in a field whose unit is not established anywhere else in this product's own data, and a compressor bought on a delivered-air number that turns out to be wrong is an expensive mistake. If your decision turns on flow at a stated pressure, ask us and we will confirm it in writing against the current Quincy sheet before you order.

Perfect For

• Independent shops on single-phase service — the whole point of this model. No converter, no separate starter.
• Serious home and hobby garages with a panel that can carry a dedicated 230 Volt circuit for a 5 HP motor.
• Floor-limited buildings — the vertical tank gives back roughly half the floor a horizontal 80-gallon receiver takes.
• Continuous work — sanding, blasting, running more than one air tool at a time, where a duty-cycle-limited machine would be the bottleneck.

What's in the Box

The compressor as a complete factory assembly: two-stage cast-iron belt-drive pump with aluminium head and stainless reed valves, heavy-duty capacitor-start industrial motor with built-in thermal overload, factory-fitted magnetic starter, high-efficiency finned tube intercooler, large balanced cast-iron flywheel, enclosed belt guard, oil sight glass, vertical 80-gallon tank with safety relief, drain and 3/4" outlet.

Not included: aftercooler, air dryer, filtration, regulation or any shop plumbing. There is no electronic drain valve on this model — draining the tank is a manual routine, and it is the routine that decides whether the receiver rusts.

Specifications

Motor and supply

Pump

Tank, size and weight

Certification, stated plainly

Two claims sit in this product's data. The receiver is built to the American pressure-vessel code with relief valves, and the electrical components carry UL and CSA recognition — the tank as a vessel, the electrical parts as components.

What the data does not claim is a third-party safety listing of the complete packaged machine as installed. That is a different document, and some insurers, fleet standards and local inspectors ask for it specifically on hard-wired shop equipment. We are not going to imply one exists. If your installation depends on it, ask us before you order rather than after the machine is bolted down.

Shipping and receiving

This ships as palletised freight within the lower 48 states, free of charge.

Work out how it comes off the truck before you order. The driver's responsibility ends at the tailgate, so a dock, a forklift, or a pallet jack on level ground is what you want waiting. If you have none of those, take terminal pickup and collect it from the carrier yourself. Delivery to a home address is a residential delivery and carries a residential fee — better settled now than argued about in your driveway. Inspect it before you sign: damage noted on the bill of lading in front of the driver is claimable, damage found after a clean signature usually is not.

Warranty

Quincy covers this compressor with a 1-Year factory warranty which extends to the 3-Year "No Bull" warranty. That extension is not automatic across the QT Pro range — on Quincy's terms it depends on the maintenance kit and on registering the unit — so read the warranty handbook linked on this page first.

One rule of ours protects whatever cover you hold: if the pump develops a fault, leave it assembled. Once it has been taken apart nobody can establish what failed first, and a claim on a stripped pump is a very hard conversation to win. Tell us what it is doing and let it be assessed whole.