Gardner Denver ELECTRA-SAVER II Service Manual page 39

160" F. This system provides proper compressor warm-up
and prevents moisture contamination of the oil
(screening) to remove debris sand andlor silt in the cooling
water suPPlY. However chemical treatment methods may
be necessary in certain instances to inhibit corrosion and/
or remove suspended solids to alter the water's tendency to
form scale deposits or prevent growth of microorganisms
The normal maintenance program for the unit should in-
clude periodic cleaning on the tube side (water side) of the
heat exchanger to remove deposits which enhance fouling
and corrosion.
WATER FLOW CONTROL VALVE FOR HEAT EX-
CHANGER (Optional Equipment – Recommended To
Conserve Water Where Appropriate) ( Figures 1-5, 7-5
& 8-5) – The water flow control valve is adjustable to comp-
ensate for varying water inlet temperatures and pressures
Use the compressor discharge air temperature gauge on
the instrument panel in setting the flow control valve The
compressor discharge temperature must be maintained a
minimum of 10° F. above the dew point temperature at the
maximum anticipated ambient refer to Figure 8-5 for the
To check element heat in oil — it should be fully extended
at 160° F. If unit shuts down due to high air discharge
temperature the cause may be that the element is stuck
open to the bypass in which case lines 1 and 2 (Figure 1-5)
will be hot to the touch and lines3 and4 much cooler. When
flushing the oil system remove mixing valve and clean all
parts thoroughly.
OIL IN
FROM
COOLER
OIL IN
FROM
RESERVOIR
CAPILLARY TUBE
Y
676347
OIL TO
COMPRESSOR
ADJUSTING
SCREW
\ .
SETTING ~ "
SCALE FIGURE 6-5. – THERMAL CONTROL
(THERMOSTATIC MIXING) VALVE
COMPRESSOR OIL COOLER – WATER-COOLED
HEAT EXCHANGER (Figure 3-1 ) – The heat exchanger
oil cooler is a multiple pass type, with water in the tubes
and oil in the shell. The oil temperature is controlled by
the thermal control (thermostatic mixing) valve. The optional
water control valve may be used to conserve water.
VAL
A74099A
HEAT SENSING BULB
/
Oil cooler malfunction may be traced by checking pres
sure at oil inlet and outlet Fitting in the oil
cooler
at
these locations are equipped with a pipe tap for a gauge.
At normal operating air service pressure (65 to 150 PSIG)
with unit warm a pressure-drop of 2 to 25 PSI can be
expected between the oil inlet and the oil outlet
FIG
IRE 7-5. – WATER CONTROL VALVE
2UI
220
m
180
I@
la
lm
lW
M
m
a
Water pressure drop from water inlet to outlet will vary
with the inlet pressure and amount of water flowing A
normal pressure drop may range from 5 to 10 PSI. Any
change in the pressure drop from that normally held may
indicate tube leakage or fouling and should be investigated
In many instances the cooling water supply for the heat
exchanger will contain impurities dissolved in solution and/
or in suspension These substances can cause scale forma
tions corrosion and fouling (plugging) of any water-cooled
heat exchanger equipment Disregarding the possibility
that one or more of these conditions exists may result
in increased maintenance and operation expense reduced
equipment life and emergency shutdown. It is strongly
recommended that a reputable local water treatment con
tern be engaged to establish the corrosion Scale-forming
and fouling tendency of the cooling water and take steps
necessary to remedy the situation if a problem does exist
The need for water treatment may only involve filtration
m
40
m .80
100 120
MWENT TW. - *F
FIGURE 8-5. – DEW POINT TEMPERATURE
VS AMBlENT TEMPERATURE
(100% RELATIVE humidity
13-9-630 Section 5
Page 5