Atlas Copco ZT 55 VSD Oil-free Tooth Air Compressor

The Atlas Copco ZT 55 VSD is the 55 kW (75 hp) flagship of the air-cooled ZT 15-55 VSD oil-free tooth compressor line, published at 8.6 and 10 bar(e) with three measured points in each class. Its two classes do not split into distant flow ranges: at Minimum the 8.6 bar(e) class opens at 42.4–143.7 l/s and the 10 bar(e) class at 34.8–139.1 l/s, and at Maximum the same classes close at 138.8 l/s and 122.0 l/s. Both classes carry an integrated dryer option — ID / IMD on the 8.6 bar(e) class and ID on the 10 bar(e) class — so treated air can leave the same 2440 mm canopy instead of a separate skid. For a hall without a cooling-water loop, that combination of air cooling, Class 0 oil-free air and integrated treatment defines the machine’s role.

Three Measured Points on Each ZT 55 VSD Pressure Class

The data sheet prints every class as three rows: Minimum at 4 bar(e), Effective at 7 bar(e) on the lower class and 9 bar(e) on the higher class, and Maximum at rated pressure. The ZT 55 VSD drives all six rows from one 55 kW (75 hp) motor, and the sound pressure level at the work station is listed at 78.5 dB(A) for both classes.

Read the rows from the top of each class: the upper flow edge drops only from 143.7 to 138.8 l/s inside the 8.6 bar(e) class, a band of 4.9 l/s across the whole pressure travel, while the 10 bar(e) class gives up 17.1 l/s of upper flow for the extra pressure headroom. A header that sits near 7 bar(e) is sized against the Effective row at 143.0 l/s, and a line that works close to rated pressure reads the Maximum row, where the m³/min column narrows from 2.5–8.6 to 2.5–8.3. The ZT 55 VSD therefore trades top-end flow, not low-speed floor, between its two classes — both Minimum rows start at 4 bar(e) with the lower class holding 4.4 l/s more than the higher one at 42.4 against 34.8 l/s.

Where the ZT 55 VSD Sits in the 15-55 VSD Range

The 15-55 VSD platform lists its air-cooled VSD models from ZT18VSD-10 up to the ZT 55 VSD, and the water-cooled branch runs from ZR37VSD-8.6 to the ZR 55 VSD. The VSD⁺ models in this line end at ZT 50, so the 55 kW point is reached only through the standard VSD machines. The table below reproduces the published VSD rows, and it shows the ZT 55 VSD sharing its 78.5 dB(A) and 1481 kg standard weight with the ZT45VSD-8.6 directly below it.

Weights, Dimensions and the Integrated Dryer Footprint

The ZT 55 VSD lists a standard model weight of 1481 kg and a frame of 2440 × 1016 × 1880 mm, dimensions the platform shares across the ZT 30-55 VSD group. The dryer options are printed per class: the 8.6 bar(e) class accepts the integrated refrigerant dryer (ID) or the integrated MD dryer (IMD), while the 10 bar(e) class lists ID. The data sheet notes that the integrated dryer will increase the weight, so the 1481 kg figure refers to the standard model and a plant should plan the bay floor for the dryer build it orders.

Sizing an Installation Around the ZT 55 VSD

Air cooling decides where the ZT 55 VSD fits: the machine rejects its compression heat into the room air, so it suits plants with no tower and no water loop, and the 1016 mm frame width lets it replace a smaller ZT 15-55 VSD unit without rebuilding the bay. The 78.5 dB(A) figure is the A-weighted sound pressure level at the work station (LpWSAd), measured with sound intensity scanning under ISO 2151:2004 and ISO 9614/2, and the printed value carries the KpAd uncertainty correction of the test code. At the 10 bar(e) class the flow band runs 32.3–122.0 l/s at Maximum, which covers a header regulated close to 10 bar(e), and the ID option keeps dew point control inside the same canopy. A plant running mixed shifts should compare its lowest night demand against the 34.8 l/s floor of the 10 bar(e) class Minimum row before fixing the class, because the drive cannot go below the printed band.

Questions Buyers Ask About the ZT 55 VSD

Which pressure class should I quote? Size the header first. The 8.6 bar(e) class closes at 138.8 l/s and 2.5–8.3 m³/min at Maximum, while the 10 bar(e) class closes at 122.0 l/s and 2.0–7.3 m³/min, so a line regulated near rated pressure keeps 16.8 l/s more flow on the lower class. Both classes share the same 55 kW motor and 1481 kg standard weight, so the choice is set by working pressure, not by the frame.

What do ID and IMD mean on this model? ID is the integrated refrigerant dryer and IMD is the integrated MD dryer, the two treatment options listed for this range. The 8.6 bar(e) class of the ZT 55 VSD accepts either, the 10 bar(e) class lists ID, and the data sheet states that the integrated dryer increases the standard weight.

How loud is 78.5 dB(A) in practice? The value is the sound pressure level at the work station measured at rated operation, not a sound power figure, and it applies with the fully uncertain KpAd correction of the test code. The ZT45VSD-8.6 prints the same 78.5 dB(A), so the last two steps of the air-cooled VSD range share one acoustic footprint.

From the ZT 55 VSD to the ZT 75 VSD

When demand outgrows the 143.7 l/s top edge of the ZT 55 VSD 8.6 bar(e) class, the next step in the oil-free line is the Atlas Copco ZT 75 VSD, whose 8.6 bar(e) class spans 74.7–229.4 l/s at its Effective point on a 75 kW motor. Sending the measured demand profile of your header with the enquiry lets the quotation land on the model and class that actually matches the plant.