Atlas Copco FD700

2920 1371 00
21
Instruction book Oil-free Air Division
4 MAINTENANCE
Check the refrigerant flow in the sight-glass (8-Fig. 4b and 10-
Fig. 5a). Under stable, nominal load conditions the flow must
be clear. At sudden load fluctuations, bubbles may pass
temporarily with the flow. A constant bubble flow indicates
refrigerant shortage or a restriction in the system. In such case,
consult Atlas Copco. Check the colour of the moisture indicator
(see section 1.3). If moisture is indicated, consult Atlas Copco.
Maintenance and repair work other than routine attention,
especially on the refrigeration circuits, must only be carried
out by qualified personnel and with the proper equipment.
Safety precautions
When handling refrigerant R404a, all applicable safety
precautions must be observed. The following points are
specially stressed:
- Contact of refrigerant with the skin will cause freezing.
Special gloves must be worn and in case of contact, the
skin should be rinsed with water. On no account may
clothing be removed.
- Fluid refrigerant will also cause freezing of the eyes;
therefore, safety glasses are a must.
- Refrigerant R404a is not inflammable but it is poisonous.
Do not inhale refrigerant vapours. Check that the working
area is adequately ventilated.
Local law may impose that:
- work on the refrigerant circuit of the cooling dryer or on
any equipment which influences its function should be
executed by an authorized control body.
- the installation should be checked once a year by an
authorized control body.
General
1. Keep the dryer clean.
2. On air-cooled dryers, brush or blow off the finned surface
of condenser (3-Figs. 4) regularly.
3. Once every six months inspect and clean the inner
components of condensate trap (1-Figs. 4 and 6-Figs. 5).
5 SETTINGS
The regulating and safety devices are factory-adjusted to obtain
optimum performance of the dryer. Altering the setting of any
of the devices must be avoided.
5.1 Automatic expansion valve
The automatic expansion valve (7-Fig. 4b and 9-Fig. 5b) is a
regulator which keeps the evaporator pressure, and
consequently also the temperature, stable. The valve is factory-
set to keep the evaporator pressure at no-load at a minimum of
5.2 bar(e) (75 psig), which corresponds to 1°C (34°F).
5.2 Switches (Fig. 4b)
Fan control switch (S3) and high pressure shut-down switch
(S2) are factory-adjusted and must be replaced if they deviate.
Cut-out at: Switch-on at:
bar(e) psig bar(e) psig
Fan control switch
50 Hz 16.9 245 18 261
60 Hz 17.9 260 19 276
High pressure
shut-down switch . . . . . . . 29 421 25.7 373
1. Key, value up
2. Key, value down
3. Display
4. Key, differential value (∆T)
5. Key, set point of maximum pressure dewpoint
Fig. 11. Detail of pressure dewpoint indicator