Gardner Denver AUTO SENTRY EAU99G Operating And Service Manual page 58

Air/oil under pressure will cause severe personal injury or death. Shut down
compressor, relieve system of all pressure, disconnect, lockout and tagout
power supply to the starter before removing valves, caps, plugs, fittings, bolts
and filters.
Compressor, air/oil reservoir, separation chamber and all piping and tubing
may be at high temperature during and after operation.
It is mandatory that any water cooled unit be installed in a shelter heated to
temperatures above freezing (32° F, 0° C).
COMPRESSOR OIL COOLER - WATER-COOLED HEAT EXCHANGER (
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 (thermostatic mixing) valve. The optional water control valve
may be used to conserve water.
Oil cooler malfunction may be traced by checking pressure at oil inlet and outlet. At normal operating air
service pressure 65 psig to 150 psig, (4.5 bar to 10.3 bar) with the unit warm, a pressure drop of 3 psi to
15 psi (.2 to 1 bar) can be expected between the oil inlet and the oil outlet.
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 psi to 10 psi (.3 bar to .7 bar). 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 in solution
and/or suspension. These substances can cause scale formation, corrosion and plugging of any water-
cooled heat exchanger equipment. Disregarding the possibility that one or more of these conditions exist
may result in increased maintenance and operation expense, reduced equipment life and emergency
shutdown. It is strongly recommended that a reputable, local water treatment concern 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 involve only filtration
(screening) to remove debris, sand and/or salt in the cooling water supply. However, chemical treatment
methods may be necessary in certain instances to inhibit corrosion and/or remove dissolved solids, to
alter the water's tendency to form scale deposits, or prevent the growth of microorganisms. The normal
maintenance program for the unit should also include periodic cleaning of the tubes (water side) of the
heat exchanger to remove deposits which enhance fouling and corrosion.
Hex head zinc anodes are used in the return bonnet (opposite end to the water pipe connections) of heat
exchangers to provide internal water system corrosion protection. These anodes should be inspected
periodically and replaced when the zinc has been reduced to about 1/2 inch (13mm) in length.
DANGER
DANGER
WARNING
13-10-614 Page 51
, page 40) - The heat
Figure 5-3