Atlas Copco ZR 55 VSD (FF) Oil-Free Rotary Tooth Air Compressor

Description

The Atlas Copco ZR 55 VSD is the largest water-cooled machine of the ZR/ZT 37-55 VSD group, rated at 55 kW / 75 hp and built around the oil-free rotary tooth element. The compression chambers run without any lubrication, so the air leaves the package free of oil, and the range carries the ISO 8573-1 CLASS 0 (2010) certification verified by TÜV.

The integrated Variable Speed Drive regulates the motor between 30 and 100 percent of maximum capacity, which turns a fixed output into a flow that follows the plant. One pressure version at 8.6 bar(e) covers free air delivery from 42.4 to 140.6 l/s, and the water-cooled circuit carries the heat of compression out of the frame for recovery elsewhere on site.

Where the ZR 55 VSD Sits in the Oil-Free Range

The ZR/ZT 15-55 (VSD) family covers 15 to 55 kW of oil-free capacity in two cooling formats, and the ZR 55 VSD closes the top of the water-cooled ladder. Below it sit the ZR 37 VSD and the ZR 45 VSD on the same platform, while the ZT 55 VSD delivers the same rating with air cooling for plants that run without a cooling water circuit.

Every machine of the group is an oil-free rotary tooth compressor: two precision machined rotors turn inside a casing without touching, and no oil enters the compression chamber at any point. The ZR 55 VSD therefore serves the processes where a single trace of oil spoils the product, and it does so in a frame that measures 2,440 mm in length.

Fixed Speed or Variable Speed

The same 55 kW rating exists in two operating philosophies. The fixed-speed ZR 55 of the ZR/ZT 55-90 platform holds a flat 148.3 l/s at 7.5 bar(e) and runs loaded or unloaded around that point, while the ZR 55 VSD slides between 41.3 and 140.6 l/s as the demand moves. A plant with a steady consumption profile takes the fixed-speed machine, and a plant whose demand swings between shifts takes the ZR 55 VSD and removes the unload losses.

The choice is not about size but about the shape of the load curve. A compressor that spends most of its hours at part load wastes energy every hour in a fixed-speed design, because the motor keeps turning at full speed while the air is blown off. The ZR 55 VSD closes that gap by slowing the motor instead.

Standard and Full Feature: What the Two Builds Add

Two delivery formats describe the ZR 55 VSD, and each answers a different installation:

• Standard — the compressor alone, with the water-cooled coolers and the oil-free element, ready to feed an air treatment chain installed downstream.
• Full Feature — the package with a dryer integrated inside the canopy, so dry air leaves the frame directly.

The ZR 55 VSD Full Feature accepts two dryer technologies. The ID refrigerant dryer reaches a pressure dew point of 3°C / 38°F at the lowest investment, while the iMD heat of compression dryer suppresses the dew point by 40°C / 72°F and reaches -20°C / -4°F at an ambient of 20°C / 68°F, with no purge air loss and no extra energy for a blower or a heater.

What the Dryer Choice Changes on the Scale

The three configurations weigh differently on the same frame. The ZR 55 VSD without a dryer weighs 1,360 kg, the ID version 1,490 kg and the iMD version 1,595 kg, while the footprint stays at 2,440 × 1,026 × 1,880 mm for every build. That shared outline lets a plant order the Standard package first and place the dryer inside the same floor space later.

An integrated dryer also removes pipework between two machines, and every connection removed is a leak and a pressure drop that no longer exists. The dryer runs under the control of the same Elektronikon unit, which reads both sides of the package and keeps the dew point within the band the process needs.

How the Integrated VSD Pays Back

Energy absorbs 70 percent of the lifecycle cost of a compressor calculated over ten years, while investment and installation take 15 percent and maintenance the remaining 15. The ZR 55 VSD attacks the largest share: the drive follows the air demand by adjusting the motor speed, which results in energy savings of up to 35 percent against a fixed-speed machine.

Regulation runs continuously between 30 and 100 percent of maximum capacity, and the motor can hold any speed in that band with no resonance frequencies to avoid. No compressed air is blown off to the atmosphere, and the network pressure stays flat instead of swinging between the load and unload set points of a fixed-speed machine.

The Drive Hardware Behind the ZR 55 VSD

• NEOS frequency converter designed in-house, mounted in a cubicle that holds stable operation up to 50°C / 122°F.
• Electric motors developed for VSD duty, with cooling designed for low speed running.
• Electro Magnetic Compliance testing and certification on every VSD compressor, so the machine does not disturb neighbouring equipment.
• Mechanical components that stay below critical vibration levels across the whole speed range.

The Elektronikon controller adds three algorithms that trim the bill further. Delayed Second Stop lets the machine stop when no motor start preceded, timer functions shut the package down when no air is needed, and a dual pressure band lowers the network pressure at nights and weekends when the process runs lighter.

Technical Specifications of the ZR 55 VSD

The table below gathers the headline figures of the ZR 55 VSD:

Rated Data at Each Working Point

The ZR 55 VSD is published with three working points on its single 8.6 bar(e) version. Free air delivery of a variable speed machine is stated at the maximum working pressure of the variant, following ISO 1217:

The span between the lowest and the highest flow at one pressure is the regulation band of the drive. At 7 bar(e) the ZR 55 VSD covers 41.3 to 139.4 l/s, which equals 87.5 to 295.4 cfm, and the minimum stays above 41 l/s at every working point.

A wide band matters most where the consumption of a plant rises and falls during the day. The ZR 55 VSD follows that curve without starting and stopping the motor, so the network pressure holds and the drive does the work that a load and unload cycle performs elsewhere.

Dimensions and Weight

The ZR 55 VSD keeps one outline across all three configurations:

All three builds share the same length of 2,440 mm and the same width of 1,026 mm, so the dryer rides inside the package rather than beside it. The ZR 55 VSD fits a single bay of a standard plant room, and no separate dryer floor space is needed.

Class 0 Air, the Tooth Element and the Drive Train

Atlas Copco pioneered oil-free air technology for more than sixty years and was the first manufacturer awarded ISO 8573-1 CLASS 0 certification. TÜV tested the range with the most rigorous methods available, measuring every possible oil form across temperatures and pressures, and found no trace of oil in the output stream.

The certification is what places the ZR 55 VSD in food and beverage plants, pharmaceutical halls and electronics rooms, where the standard defines solid particles, moisture and oil as the three contaminants to control. The Antwerp plant that builds the Z range also holds ISO 22000 certification for its food safety management system.

The Mechanical Drive Train

The ZR 55 VSD pairs the oil-free tooth element with a super premium efficiency IE4 motor and a gearbox design proven across the installed base. The oil circuit serves the bearings, the gears and the element jackets: the pump draws from the sump through the oil cooler and a high efficiency filter, and the oil returns to the gear casing. No oil ever meets the air.

That separation is the reason the tooth element runs at low speed with long service intervals. The rotors carry no contact load, the timing gears keep the clearance, and the compression heat leaves through the coolers instead of through the casing surfaces.

Water Cooling, Heat Recovery and Installation

The ZR letter marks the water-cooled format. A tube and shell oil cooler, an intercooler and an aftercooler form three parallel circuits, and the cooling water carries the compression heat away from the frame instead of into the room. That design holds the sound level of the ZR 55 VSD at 67 dB(A) and keeps the package stable in a warm machine room.

The same heat becomes an asset. Because the energy leaves the frame in the water, the ZR 55 VSD can feed a heat recovery circuit for process water, washing water or space heating, and the recovered energy raises the efficiency of the whole site.

Installation Footprint and Options

The package arrives as a plug and play unit: no interlinking of extra components, no separate compressor room needed, and a sound insulated canopy that allows installation in most working environments. Options tailor the ZR 55 VSD to the site:

• Anchor pads, ANSI flanges and a main power isolator switch for the mechanical and electrical connection.
• Integrated dryer bypass, water shut-off valve and anti condensation heaters with thermistors for humid rooms and standstill periods.
• High ambient variant, silicone-free rotor for MD and the IT variant for special process environments.
• SMARTLINK connectivity, 5% input chokes and a test certificate for documented acceptance.

Control, Monitoring and Multiple Machine Coordination

The Elektronikon touch screen runs the compressor and the integrated converter from one interface. It shows the running conditions, tracks the maintenance status, raises pro-active service indications and shuts the machine down on a safety alarm, and the operating system carries the control algorithms that trim the energy use of the ZR 55 VSD.

Where the plant runs three machines or more, a central controller takes over. The built-in EQ4i and EQ6i algorithms, the Equalizer 4.0 sequencer and the Optimizer 4.0 controller each fit a different installation size, and all of them coordinate the ZR 55 VSD with the rest of the room better than individual settings can. SMARTLINK adds remote monitoring over a secure network and reports where the energy goes.

Applications of the ZR 55 VSD

Food and beverage plants use the ZR 55 VSD for fermentation, aeration, filling and capping, where the CLASS 0 certificate removes the contamination risk from the audit trail. Pharmaceutical production relies on the same purity from tablet coating to bottling, and electronics manufacturers use the dry, oil-free air to clear microscopic debris from chips and boards.

Chemical, textile and battery plants complete the picture, and the water-cooled format suits the sites that already run a cooling water circuit for other equipment. A plant with a steady base load adds a fixed-speed machine as the base unit and lets the ZR 55 VSD trim the peaks, which is the mix that a central controller handles best.

Service and Parts Around the ZR 55 VSD

The ZR 55 VSD is built for long overhaul intervals, few service interventions and minimal maintenance cost, and every unit is tested before it leaves the line. A global service organisation with field engineers in 160 countries backs the installed base, and AIRScan audits with the AIRchitect simulation show where a running installation still loses energy.

Seadweer supplies genuine Atlas Copco parts and service kits for the ZR 55 VSD and its Full Feature variants, covering the oil circuit components, the intake and cooler parts and the dryer service items. Send us the machine model together with the parts you need, and the correct items are confirmed with the quotation in one pass.

FAQ

What does the ZR 55 VSD deliver at 7 bar(e)?

At the effective working point of 7 bar(e) the ZR 55 VSD delivers 41.3 to 139.4 l/s, which equals 2.5 to 8.4 m³/min or 87.5 to 295.4 cfm. That span is the regulation band of the drive at that pressure.

Is the ZR 55 VSD available in more than one pressure version?

The ZR 55 VSD is published in a single 8.6 bar(e) version, with a working range from 4 to 8.6 bar(e). The air-cooled ZT 55 VSD adds a 10 bar(e) version for networks that need the higher pressure.

How much does the ZR 55 VSD weigh?

The package weighs 1,360 kg without a dryer, 1,490 kg with the ID refrigerant dryer and 1,595 kg with the iMD heat of compression dryer. All three builds share the 2,440 × 1,026 × 1,880 mm outline.

How quiet is the ZR 55 VSD?

The sound pressure level reads 67 dB(A), three decibels below the air-cooled ZT 55 VSD of the same rating. The water-cooled circuit carries the heat out of the frame, which keeps the package quiet in a warm room.

What does Full Feature add to the ZR 55 VSD?

Full Feature integrates a dryer inside the canopy. The ID refrigerant dryer gives a pressure dew point of 3°C / 38°F, while the iMD heat of compression dryer suppresses the dew point by 40°C / 72°F with no purge air loss.

How oil-free is the air from the ZR 55 VSD?

The range holds ISO 8573-1 CLASS 0 (2010) certification verified by TÜV, the most stringent class of the standard. The tooth element runs without lubrication in the compression chamber, so no oil can reach the air stream.