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Hitachi Industrial Equipment Systems Co.,Ltd.

Hitachi

Oilfree Screw Compressor : DSP Series Vplus : Features

Single-stage DSP V-type has evolved into Vplus model
(22kW, 37kW, and 55kW air cooled/single-stage)

22kW single-stage model on the market now

PQ wide mode

New-refrigerant dryer

PQ wide mode

Inverter control is used to adjust the maximum motor speed of the compressor automatically. When the operating pressure is lowered, the air flow can be increased. The operable low-pressure range is even wider. Its epoch-making powersaving performance is equal to that of the conventional models. The maximum air flow is 19-28% higher (than the conventional models), thus providing leeway in the air flow.

Capacity in the PQ wide mode

Unit: m3/min

Model Discharge air pressure MPa
0.39 0.49 0.59 0.69
22kW 4.3 4.0 3.7 3.4
37kW 5.0 5.0 4.6 4.2
55kW 8.2 7.6 7.0 6.4

Note

*
Dryer built-in model has a minimum pressure of 0.49MPa in the PQ wide mode.

Capacity in the PQ wide mode

Quick action

Quick action

Shorter time for pressurization (in the PQ wide mode)

The time for pressurizing the device and air tank are shortened with the PQ wide mode ON. Because this causes the unit to run at the maximum air flow unit it reaches the lower pressure limit in the PQ wide mode. For example, when pressurizing the air tank from the atmospheric pressure to 0.69MPa with a 55kW model, the times are shorten by up to 20%. (Comparison with conventional model)

PQ wide mode switch

The PQ wide mode can be set to ON or OFF on the panel according to the needs.

To save energy securely by reducing the operating pressure
PQ wide mode[ON]
  1. When the operating pressure is reduced from 0.69MPa to 0.59MPa, the maximum power consumption is automatically reduced to about 92% of that at 0.69MPa.
  2. When the pressure is reduced to 0.49MPa, the power consumption reaches about 85%. When the pressure is reduced to 0.39MPa, the power consmption reaches about 79%. If you know your air consumption for sure and wish to reduce the power securely by reducing the pressure, it is recommended to set the PQ wide mode to OFF.
To use the compressor up to its rated maximum motive power by reducing the operating pressure
PQ wide mode[ON]
  1. Reducing the operating pressure from 0.69MPa reduces the power consumption to about 79%.
  2. With the excess motive power from depressurization, you can increase the air flow to 128% of rating. At that time, the power consumption reaches 100%. If you wish to make the most of the rated motive power of the compressor and you need a high air flow, it is recommended to set thePQ wide mode to ON.

22kW single-stage V-type

  • More energy-saving than 22kW two-stage models in the whole load region
  • The PQ wide mode achieves a capacity comparable to that of a 22kW two-stage model.
  • Being single-stage, this model does not cost much for maintenance.

Energy remarkably saved through constant pressure control

Larger capacity and higher energy-saving then two-stage models

Note

*
The chart makes comparisons based on 22kW models.
Control pressure setting of 22kW two-stage model; 0.69MPa, 22kW single-stage model; 0.59MPa

The inverter has constant pressure, so that its pressure can be set to a lower level than load/unload controllers.
The 22kW single-stage V-type is inverter-controlled, resulting in higher energy-saving than two-stage models of the same class (load/unload models) in the entire load region.
For example, at an air consumption of 60% (2.0m3/min), this model saves 1,400US$ more worth of energy than two-stage models(Conditions of calculations: Operating hours, 8000 hour/year; unit price of power, 0.07 US$kWh.).
The PQ wide mode can be used to increase the maximum capacity to a higher level than two-stage model fo the same class (load/unload models). Being single-stage, these models costs much less for maintenance.

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