Two-stage screw compressor SCR-250 H 250 kW rating, 3,090 m³/h at 7 bar, fixed speed, pressure 7 / 8 / 10 / 12.5 bar

Product detailed description

250 kW · two stages

SCR-250 H is a two-stage screw compressor rated at 250 kW and running at a fixed speed. It comes in four pressures — 7, 8, 10 or 12.5 bar — and at seven bar it gives 3,090 m³/h. The air is compressed by two blocks in series with intercooling. Noise 86 dB(A), weight 7,000 kg, DN125 outlet.

What the SCR-250 H is for

The move into the largest cabinet: 4.0 × 2.2 × 2.3 metres and 7,000 kg. From this size up the machine has two oil separator elements instead of one — more area means a smaller pressure drop and a longer life for the element.

Fixed speed

The SCR-250 H runs at a fixed speed: it either compresses flat out, or it unloads. It is a simpler machine without power electronics and it pays off where demand is even and the compressor runs all the time anyway. At this size the manufacturer does not list the motor as IE4.

What is inside the SCR-250 H

Two stages, two blocks

The air goes through two screw blocks in series. The first compresses it to an intermediate pressure, the intercooler takes the heat out of it and the second pushes it up to the outlet pressure. Both blocks are driven by one motor through a gearbox, so each of them runs at the speed that suits it. According to the manufacturer the rotors are designed for twenty years of operation and they run in SKF bearings.

The oil and how it gets out

The oil lubricates the rotors, seals the gap between them and carries the heat away. It is pulled out of the compressed air by the swirl in the large vessel and, at the end, by the fine separator element; according to the manufacturer less than 3 ppm of it then stays in the air. The pressure drop of the whole separating path is under 0.02 MPa, which goes straight into the pressure the machine has to make.

SCR9000 control

A seven-inch colour touch display. It shows the pressure, the temperature and the running hours, watches the service intervals and has over thirteen protections — from overheating through overpressure to phase imbalance. Over Modbus RTU the SCR-250 H can be tied into a network control of up to sixteen compressors; at this size there are usually several machines in the compressor room.

SCR-250 H in four pressures

Mechanically it is still the same machine — what changes is the outlet pressure and with it the amount of air. You pick the pressure at the product, and the order code changes accordingly.

The figures are the FAD output to ISO 1217, annex C.

What the machine demands of the plant

Cooling and space in the compressor room

The SCR-250 H is air-cooled as standard — the fans pull air through the oil cooler and through the aftercooler. Cold air therefore has to be brought into the compressor room and the hot air taken away. The machine measures 4,000 × 2,200 × 2,300 mm and weighs 7,000 kg, so allow for it in transport and in the assessment of the floor as well. The compressed air outlet is DN125. For hot or cramped plants water cooling is available.

What the machine costs over a year

On a 250 kW machine that runs around the clock you will pay several times more for the electricity than for the compressor itself. That is what the two stages are here for: the air is cooled between them, the second stage has an easier job, and the manufacturer puts the resulting saving at over ten percent against a single-stage machine at full load. If your demand swings, have a look at the HPM version with a drive as well.

Where the air from the SCR-250 H is used

The series is built for plants that take air all the time and in quantity, and where the yearly electricity bill counts for more than the purchase price. The air is oil-lubricated — where it touches the product, the oil-free series belongs instead.

Equipment and accessories

What the SCR-250 H does as standard

• Two-stage screw block with a gearbox and SKF bearings
• Intercooler between the stages and an aftercooler at the outlet
• Oil separator vessel, oil content in the air below 3 ppm — with two elements at this size
• Intake filter with a double element and a clogging indicator, 2,000 hour interval
• Oil filter with a separation rating of 0.1 µm
• SCR9000 controller with a seven-inch touch display and Modbus RTU
• Electrical switchgear with Siemens components
• Internal air and oil pipework entirely in steel
• Unloaded running with an automatic restart after a power failure

What can be ordered on top

• Water cooling instead of air cooling
• Heat recovery into service water heating
• Aftercooler (the manufacturer lists it as optional)
• Extended five-year warranty

Where to look next

From two hundred and fifty kilowatts up the machine has two oil separator elements and the largest cabinet of the series. The smaller machine in the middle cabinet is SCR-220 H. Above it there remains only SCR-280 H. The variable-speed version is SCR-250 HPM.

Outputs, dimensions, weights and connections are stated by the manufacturer, the noise levels and order codes by the importer. The output is measured to ISO 1217, annex C. The figures hold for standard conditions; in heat, at altitude or in a dusty plant the machine has to be assessed separately. We reserve the right to make changes without notice — the order confirmation is what counts.