ABAC FORMULA Series Use And Maintenance Handbook Download

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P. 68 - Chap. 10 Maintenance

Maintenance

Perform the

scheduled maintenance operations to maintain compressor performance

Various routine maintenance operation can be carried out by user provided they are carried out by

skilled personnel.

If routine maintenance is provided by a Service Centre, the user cannot RESET the components even
if these have been replaced by the user (see paragraph 7.4.2.2)
Use only original spare parts

Instructions are provided in the following paragraphs.

Before performing any maintenance operations read the operator safety precautions in

chapter 5 carefully. These precautions must be followed scrupulously for all maintenance

operations

Operating cycle

10.1

The compressor unit consists of two rotors (male and female) with special asymmetrical proﬁle, patented VT
series, mounted on rolling bearings, able to withstand axial and radial thrust. The male rotor is the driving rotor
while the female rotor is driven. The male rotor also rotates the female rotor. The two rotors are not however
in contact physically as they are separated by a thin ﬁlm of oil that protects the coupled surfaces. The male
rotor drives and the female rotor is driven. The two rotors are not in direct contact thanks to a thin ﬁlm of oil
which protects the coupled surfaces.
The oil serves various purposes. It lubricates the bearings and the rotors, eliminates the heat produced by
the compressed air, it creates an “airtight ﬂuid seal” and reduces hazardous gaps in the air-end unit.

In ﬁxed speed compressors, starting is of the delta-star type. During the star phase, intake valve

is closed,

thus permitting no-load start-up with less effort and lower energy consumption.
After a preset time of a few seconds, the PC control unit invokes changeover to the delta connection; with a
short transient phase, the

motor reaches rated rotation speed. The intake valve opens thus starting the

normal work cycle.
In variable speed compressors, the start-up phase takes place with acceleration of the electrical motor which,
powered by the inverter, is brought to maximum speed of rotation compatible with network pressure.
As soon as this is permitted by rotation speed, the intake valve

opens and the machine work cycle

begins.

The air is drawn through the ﬁlter

, passes into the air-end unit where it is mixed with the oil injected. The air is

gradually compressed and pushed into the separator receiver where initial oil separation occurs by gravity.
The air, which is still mixed with oil droplets, follows the shape of the receiver and passes through the oil
separator ﬁlter

. Due to the effect of coalescence, the droplets of oil merge and are deposited on the bottom

of the ﬁlter from where they are routed towards the air-end unit by means of a pipe.
The puriﬁed air passes through the check and minimum pressure valve

which opens only when a threshold

of approximately 4 bar is exceeded. This ensures correct system lubrication in all operating conditions.

The oil deposited on the bottom of receiver

is conveyed under pressure to the oil radiator

where it

is cooled. If the temperature of the oil is below the calibration value of the

thermostatic valve, ﬂow to the