Schulz SRP 4008 Dynamic — A Rotary Screw That Runs on Single-Phase 230 Volt

Rotary screw compressors are usually a three-phase conversation, and that is where the shortlist ends for a great many workshops. Plenty of buildings — home shops, small units, older commercial premises, farm and estate workshops — have no three-phase service at all, and getting one installed can cost more than the compressor. Those buyers are normally pushed back towards a piston machine and told to live with the duty cycle.

This listing is the exception. The SRP 4008 Dynamic in this configuration runs on 230 Volt single-phase supply, and it is a genuine oil-injected rotary screw: 7.5 HP, 25 CFM at 125 PSI, continuous 100% duty cycle, on a 60-gallon horizontal ASME receiver, inside a sound-attenuated cabinet rated at 69 dB(A).

What you actually gain over a piston machine

The headline difference is the duty cycle, and it is bigger than it sounds. A reciprocating compressor is rated to run for a portion of each hour and to stand idle for the rest, so the airflow on its badge is a peak rather than a supply you may plan on. Exceed the rating and you are simply spending the machine's life early — hot oil, tired rings, and a pump that quietly stops making its numbers.

A screw carries no such restriction. It has no reciprocating mass and no valve train beating itself to death, and this one is rated to run every minute of every hour. So 25 CFM at 125 PSI is a figure you can size an air system against. In practice a modest continuous supply often outperforms a much larger piston machine on paper, because you can use all of it, all day.

The second gain is noise and heat. The enclosure holds the machine to 69 dB(A), and Schulz publishes an ambient operating ceiling of 113 °F, so this is a compressor you can put in the same room you work in and in a space that is not climate-controlled.

A note on the starter description

The manufacturer's feature list for the SRP 4008 family mentions automatic starters with phase and sequence failure detection. Phase sequence is a three-phase concept — on a single-phase build there is no rotation order to get wrong — so that line is written for the range rather than for this configuration. Nothing about it is alarming, but if the exact protection fitted to the starter matters to your installation or your electrician, ask us and we will confirm what this specific build ships with rather than guess from a shared bullet list.

Will It Fit?

The compressor and its receiver are one 2-in-1 assembly, so there is a single item to position and no interconnecting pipework to have made up. It measures 49.4" long, 23.6" wide and 53.5" tall, and weighs 500 lbs. The tank outlet is 1/2".

It wants a flat, solid floor; that weight rests on the mounting feet, and a slab with a dip in it will work them loose over time. Leave space around the cabinet for cooling airflow and for the service panels to open.

On the electrical side, single-phase does not mean casual. A 7.5 HP motor on a single-phase supply draws a substantial current, and Schulz publishes both the amp draw and the recommended breaker as "consult a certified electrician" — the honest answer, because the conductor size follows your run length and your local code. Check that your panel has the spare capacity before you order rather than after the machine is on your floor. That verification is the customer's responsibility.

Control

A 24 Volt microprocessor controller runs the machine, with adjustable operating parameters and a constant readout of what it is doing. On a compressor bought by a shop without an on-site engineer, that matters more than usual: it turns a fault into something displayed rather than something diagnosed by ear. A magnetic starter is fitted, and an air filter is supplied.

Perfect For

• Buildings with no three-phase supply — the entire reason to look at this listing.
• Serious home and hobby workshops that have outgrown a piston compressor's rest periods.
• Single-bay independents and mobile fit-out shops needing continuous air from a modest machine.
• Farm, estate and rural workshops a long way from an economical three-phase connection.
• Anywhere the compressor lives in the working space — that is what the enclosure is for.

What's in the Box

One complete factory-assembled unit: the rotary screw air end, the TEFC IP55 electric motor, a magnetic starter, the 24 Volt microprocessor controller, an air filter, the sound-attenuated cabinet, the 60-gallon horizontal ASME receiver it is all mounted on, an oil sight glass and a 1/2" tank outlet.

Not supplied: the data records no air dryer, no electronic drain valve and no pump low-oil shut-off on this model. Air treatment, drainage arrangements, shop pipework and the electrical connection are all separate.

Specifications

Supply

Air end

Receiver, size and environment

Certification, stated without decoration

The receiver is an ASME certified pressure vessel: built and stamped to a recognised pressure-vessel code. On a tank sitting at 125 PSI in a workshop, that is the claim with substance behind it, and it is the claim this product's data makes.

The data makes no other. There is no record of an independent third-party listing covering the machine as a finished assembly — motor, starter, controller and cabinet evaluated as one product — and a vessel stamp is not a substitute for one. We would rather say that plainly than let the two blur together. It matters more than usual on a single-phase installation in a domestic or semi-domestic building, where an insurer or an inspector is more likely to ask. If that describes you, contact us before ordering and we will confirm in writing what documentation exists.

Getting it delivered

This ships as palletised freight across the lower 48 states. The cost is quoted live at checkout for the address you enter, not taken from a rate chart.

Think about the unload early, because this is the model most likely to be going somewhere without a dock. A freight driver's responsibility ends at the tailgate, and 500 lbs on a pallet is a forklift job, or a pallet jack on flat, hard ground. If your address has neither, terminal pickup is usually the better plan: you collect from the carrier's depot with your own transport and equipment. Home addresses are handled as residential deliveries and carry a residential fee. You can also collect from our Schulz pickup point in Acworth, Georgia.

Inspect the pallet with the driver present and write any damage onto the bill of lading before signing. That note is the thing a claim rests on afterwards.

Warranty

The specification block records 1 Year consumer and 1 Year commercial cover on this model, with nothing extra to buy to keep it in force.

One request protects it: if the machine develops a fault, do not take it apart first. Once a screw air end has been opened, nobody can establish the order in which things failed, and the claim rarely survives that. Call, text or chat with us on 866-774-7743, tell us what it is doing, and let it be assessed as a complete unit.