QRS3.0HPD-3: 3 HP of three-phase air, built to run all day rather than all at once

A 3 HP compressor wired for three-phase supply is an unusual specification, and it tells you what this machine is for. Most equipment at this power is single phase, because most equipment at this power is a tool that gets switched on when someone needs it. This is not that. It is a small utility built to sit in a plant room and supply air continuously — 100% duty, 8.5 CFM at 150 psi, a 60 gallon ASME/CRN receiver and an integrated dryer — and to be forgotten about between services.

The motor is a TEFC Baldor. Naming the motor manufacturer is not standard practice on compressor listings, and it is worth something: when a bearing set or a replacement is eventually needed, a branded motor with an established service network is a part you can source rather than a mystery you have to send away. The range is produced in Italy by Atlas Copco. A summary field on this page rounds the output to 9 CFM, which is the same number as the 8.5 CFM the feature list gives.

Voltage: this machine is dual voltage, and you should know which one you have

The listing specifies 208-230/460V for three-phase service. A dual-voltage motor is configured at commissioning for whichever supply the building actually has, which has two consequences worth planning around. First, tell whoever installs it which voltage your service is — this is not something the machine works out for itself. Second, the compressor is not stranded if you move premises or the electrical service changes; the same unit can be reconfigured rather than replaced. On a machine intended to be a permanent fixture, that is a longer-term asset than the price difference between voltages.

Why continuous duty matters more at 3 HP than at 30

The instinct is that duty ratings only matter on big compressors. The opposite is closer to the truth. Small compressors are the ones routinely asked to run constantly at low flow — supplying assist air to a cutting table, control air to pneumatic valves, bench air to a laboratory or a small production cell — and a piston compressor in that role is running far outside the rest periods it was rated for. It gets hot, its oil degrades, and it fails years earlier than its owner expected while never once being asked for a lot of air at any single moment.

A 100% duty screw airend has no rest requirement to violate. You size it against total consumption and stop thinking about it. That is the whole argument for putting a screw compressor at the small end of the range, and it is why this machine ends up in buildings that would otherwise have bought a piston unit twice.

Start/stop control

Unlike the larger units in this family, which unload and then shut down on a timer, this one uses start/stop operation. For a small compressor with intermittent demand that is the efficient choice — there is nothing gained by keeping an airend turning while it makes no air. The control panel is UL and cUL approved.

Drying, included rather than deferred

The air dryer is integrated into the package. At this scale that is the single most valuable thing on the specification sheet, because a separate dryer is the component small installations put off and then never buy. The result of not having one is not dramatic; it is slow. Moisture condenses in the pipework, reaches valves and instruments and tools, and quietly corrodes things from the inside over a period long enough that nobody connects the cause to the effect. Buying the drying with the compressor removes both the decision and the sizing error that usually accompanies it.

The receiver, and what CRN is doing there

The tank is 60 gallon, and it is described as ASME/CRN. The first part is the pressure-vessel construction standard. The second is Canada's registration system for pressure vessels: a CRN-registered tank has paperwork a Canadian inspector can accept, which many otherwise identical receivers do not have. In the United States that costs you nothing. In a jurisdiction where registration is a precondition of commissioning, it is the reason to specify this tank rather than argue about another one.

Will it fit, and will it run?

Confirm the electrical service first — three-phase at 208-230/460V — and confirm which of the two voltages it is. Physically, budget for around 56.3 inches of length and roughly 452 lbs, which is a pallet-jack move through a standard door rather than a rigging exercise. The tank outlet is 1/2 inch. Leave genuine clearance on the cooler side: an enclosed package with a dryer inside it rejects more heat than a bare compressor, and heat is what an enclosure is worst at getting rid of. The listing also holds an overall width and an overall height, but both are stored with no unit attached, so we are not going to publish them as measurements; ask and we will send the dimensioned drawing from the manual instead. Verifying supply, clearance, ventilation and floor loading before delivery is the buyer's responsibility.

Perfect for

• Plant rooms and utility spaces in buildings with three-phase service that need a permanent, low-flow air supply.
• Cutting tables, control air and instrument air, where demand is small but effectively constant.
• Noise-sensitive premises — 61 dBA in a low sound enclosure means the compressor does not need its own room.
• Canadian installations where a registered pressure vessel is required before sign-off.

What is in the box

Per this listing: the 3 HP TEFC Baldor motor and airend, the integrated air dryer, the low sound enclosure, start/stop control with an approved panel, and the 60 gallon ASME/CRN tank. Downstream filtration, an automatic condensate drain, isolation valves, pipework and an electrical disconnect are not stated as supplied — assume they belong to your installation unless we confirm otherwise in writing.

Specifications

Approvals, stated plainly

This product's data makes exactly two approval statements and we are going to leave it at exactly two. The control panel is UL and cUL approved. The receiver is ASME/CRN. One covers the electrical side, the other covers the pressure vessel, and together they are more than many compressor pages in this class actually state. Nothing in the data claims any further agency listing or third-party mark, and we are not going to gesture at one with vague wording. If a specifier, an insurer or a safety programme in your organisation needs documentation beyond those two, ask us before the order goes in and we will request it from the manufacturer in writing rather than let you assume it arrives in the crate.

Shipping and delivery

Freight only, palletised, into the lower 48 states, with the rate quoted live at checkout rather than estimated, so it reflects the lane on the day you order. Around 452 lbs needs to come off the truck: a forklift, a dock, or a collection from the carrier's terminal, which is a sensible option for a plant room installation where there is no loading equipment on site. Residential delivery carries a residential fee. Inspect before signing. On an enclosed machine, damage hides behind panels, so look along the enclosure edges and at the cooler, and write whatever you find on the bill of lading in front of the driver. A note at the point of delivery is what makes a damage claim straightforward; a call afterwards rarely does.

Warranty

The listing gives a single term: 5 years, conditional on an authorized start-up, and it invites you to contact us for the specifics. We are reproducing that as written rather than filling in a standard period the page does not state — ask and we will confirm the terms in writing before you commit. Regardless of the term, one rule applies to every compressor we sell: do not take the airend, the dryer circuit or the control panel apart before a claim has been opened. A unit that has already been dismantled is extremely difficult to claim on.