Atlas Copco ZR 250 VSD (iMD VSD⁺) Oil-free Air Compressor

The Atlas Copco ZR 250 VSD is the water-cooled, two-stage oil-free screw compressor in the 250 kW (335 hp) class of the ZR/ZT 160-315 (VSD) range. The family spans the current Pack build, the FF (iMD) build with an integrated heat-of-compression dryer, and the ZR 250 VSD+ branch in Pack and FF (iMD) forms. Because the NEOS inverter synthesizes its own motor frequency, the published performance applies to 50 Hz and 60 Hz plants in one table per build. Air ends run through filtration, first-stage compression, an intercooler with moisture separation, and a second stage to the final pressure.

Class 0 air leaves the package with zero risk of oil contamination, which is why food, textile, medical, and electronics plants specify the ZR line. The variable speed drive tracks the demand curve instead of cycling load and unload, and the two-stage element keeps the pressure ratio split across both stages for cooler, more efficient compression.

Turn-down defines the daily value of the ZR 250 VSD. On the 8.6 bar(e) variant the flow modulates from 774 l/s at full speed down to 284 l/s at the top pressure setting, so a filling hall that breathes between shifts never forces the package to blow surplus air to atmosphere. Network pressure holds inside a narrow band, downstream equipment sees a steady supply, and the safety margin plants normally hold against fluctuation can shrink.

المواصفات الفنية

Performance follows ISO 1217, Annex E, Edition 4 (2009), with FAD measured at the effective working pressure of each setting. The Pack table below lists the two factory variants, 8.6 and 10.4 bar(e), each with its minimum, effective, and maximum pressure setting.

The Pack build measures 3116 mm long, 1757 mm wide, and 2152 mm high, and the noise level reads 71 dB(A) at the work station. Both variants share the same 250 kW (335 hp) permanent magnet motor, so the choice between 8.6 and 10.4 bar(e) follows the network pressure alone. A blow off valve and two pressure relief valves after the moisture separator safeguard the package across the envelope.

The FF (iMD) Build with Integrated Dryer

The FF (iMD) build carries a heat-of-compression adsorption dryer inside the same canopy. About sixty percent of the flow passes the aftercooler while the hot remaining share regenerates the adsorption drum, so dry air leaves the outlet flange without a separate dryer row in the compressor room. Because the dryer needs a higher minimum setting, the FF tables start at 6 bar(e) on the minimum setting.

The integrated dryer extends the frame to 4486 mm in length while width and height stay at 1757 and 2152 mm. Wiring and piping between compressor and dryer are completed and tested in the factory, which removes field plumbing, cuts connection pressure drop, and frees floor space beside the machine.

The ZR 250 VSD+ Branch

The ZR 250 VSD+ build takes its own Pack form with a shorter frame and comes only as a 10.4 bar(e) variant. Its noise level reads 73 dB(A), and the Pack enclosure measures 3044 mm long, 1760 mm wide, and 2150 mm high.

The ZR 250 VSD+ FF (iMD) form adds the integrated dryer to that platform: 251 to 796 l/s at the 7 bar(e) effective setting, the same 73 dB(A) level, and 6687 kg of packaged weight on a 4414 by 1760 by 2183 mm footprint. Buyers comparing the two branches should weigh the wider turn-down of the VSD+ build against the current machine’s cooler package and its two-variant pressure choice.

Inside the Package

Two next-generation compression elements with superior rotor coating split the pressure between stages, and the gear drive between the motor and the elements runs in filtered, temperature-controlled oil. The NEOS inverter adjusts motor speed continuously for energy savings of up to 35 percent against fixed speed operation, and the permanent magnet motor holds class-leading efficiency across that speed range.

The Elektronikon Mk5 Touch controller supervises the package with warning indications, maintenance scheduling, and online condition visualization. A bearing life monitor runs independently of compressor speed, the IP54 cubicle keeps dust out of the electrical section, and stainless steel coolers with a highly efficient water separator hold performance over the service life. Energy recovery can capture up to 94 percent of the electrical input as hot water for processes or space heating.

The air path inside the ZR 250 VSD is laid out for minimal pressure drop: intake air crosses the air filter and inlet valve, passes the pulsation dampener into the first stage, and flows through the intercooler with its moisture separation system and automated drains before the second stage. Zero-loss drains clear condensate without wasting compressed air, the soundproof canopy with optimized internal ducting keeps the work station quiet, and grouped service items shorten every maintenance stop.

Where the ZR 250 VSD Fits

Plants with a steady water circuit and heavy, shifting demand gain the most: the drive rides filling cycles, batch changes, and seasonal swings without unload blow-off. Sites that order air treatment separately can keep the Pack build and pipe a standalone dryer, while turnkey projects take the FF (iMD) build and connect one air main. For the air-cooled counterpart in the same output class, the Atlas Copco ZT 250 VSD Oil-free Air Compressor covers the same envelope without cooling water.

Engineering teams that plan capacity in stages also fit the ZR 250 VSD into a multi-machine room: the central controller groups the package with existing fixed speed units, trims the average pressure band, and lets the variable speed machine carry the trim duty while base machines run at their efficient full-load point. Options such as a silicone-free rotor, high ambient temperature versions, and witnessed performance testing tailor the package to demanding sites.

ZR 250 VSD FAQ

What does the Pack build include?

The Pack form carries the compressor, motor, inverter, coolers, and Elektronikon control as one tested unit, with the air treatment left to plant-side equipment.

How large is the capacity envelope?

On the 8.6 bar(e) variant flow spans 284 to 774 l/s (602 to 1640 cfm) across the pressure settings, and the 10.4 bar(e) variant covers 266 to 705 l/s.

Why does the FF (iMD) table start at 6 bar(e)?

The heat-of-compression dryer needs a minimum circuit pressure to regenerate the adsorption drum, so the minimum setting rises from 4 to 6 bar(e) on the integrated build.

What separates the ZR 250 VSD+ from the current build?

The VSD+ branch comes as a single 10.4 bar(e) variant with a shorter 3044 mm Pack frame, 73 dB(A), and a wider turn-down that reaches 210 l/s at the bottom of its envelope.

Does the machine need cooling water?

Yes, the ZR is the water-cooled line, and the recirculated water carries the intercooler, aftercooler, and oil cooler duty; the ZT counterpart rejects its heat to ambient air instead.

Which industries specify this compressor?

Food and beverage, pharmaceutical, textile, chemical, and electronics plants take the Class 0 oil-free air for direct product contact and instrument duty.