Service Adjustments; Differential Pilot Valve; Water Temperature Regulating Valve; Water Cooled Heat Exchangers - Quincy Compressor QMA Series Instruction Manual

SECTION KU - SERIZCE
ADJUSTMENTS
*Diff~~~~ti~
pilot v~v'e
*Pressure Switch
*Water Temperature Regulating Valve (Water-Cooled
units only)
*Water-Cooled Heat Exchangers
Differential Pilot Valve
Open a manual vent valve to allow the compressor to
exhaust air to the outside and start the unit. By manual
regulation, slowly close the valve allowing the unit to
build air pressure to the desired modulation point and
hold. Adjust the screw on the bottom of the differential
pilot valve so that a slight stream of air can be felt
coming from the orifice adjacent to the adjustment
screw.
When this air is felt, air is beginning to pass through
the pilot valve to the air cylinder on the inlet valve,
causing the valve to modulate toward its closed
position, thereby, reducing the volume of air being
compressed.
.. .
To raise pressure, turn the adjusting screw in
(clockwise). To lower pressure turn the screw out
(counter clockwise). Maximum fill load pressure for
each model is listed in the QMA Specifications. Never
exceed these pressures. Minimum fuI1 Ioad pressure is
75 PSIG.
Pressure Switch
The pressure switch determines at what pressure the
compressor will load and unload. Standard factory
settings are listed in the QMA Specifications. Never
exceed these pressures. If a lower setting is desired,
adjust the differential pilot valve first and set the
pressure switch cut-out point to 15 PSIG over the
desired full load pressure. The range adjustment is
made by turning the screw clockwise to increase the
cut-inkut-out pressure and counter clockwise to lower
cut-infcut-out pressure.
>. ".
!wARN~G!
Never adjust the pressure switch higher than the
factory setting. Severe personal injury, death
and compressor or property damage may result.
Water Temperature Rewdatin~ Valve
fWater-CooIed Units Onlv\
The water temperature regulating valve senses fluid
temperature and opens or closes regulating water flow
from the unit. It is factory set to maintain 180° F air
discharge temperature. Due to ditTerent incoming water
temperatures and/or pressures at the customers locatio~
valve adjustment should be checked during start-up to
maintain 180° F discharge temperature. To increase
fluid temperature, decrease water flow by turning the
adjustment screw clockwise. To decrease fluid
temperature, increase water flow by turning the
adjustment screw counter clockwise.
Water-Cooled Heat Exchan~ers
The majority of fluid/water heat exchanger problems
are due to underestimating the importance of water
treatment and heat exchanger maintenance. Efficient,
long service ltie can be obtained only when clean, soft
and/or treated water is used and the exchanger tubes are
cleaned on a regular basis. HEAT EXCHANGER
IGUARANTEES DO NOT COVER FAILURES
CAUSED BY CORROSION OR PLUGGING,
In some instances, the cooling water supply for the heat
exchanger will contain impurities dissolved in solution
and/or in suspension. These substances can cause scale
formation, corrosion, fouling and 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. In some cases, what is normally
considered plain drinking water, can contain corrosive
substances that will impact the heat exchanger's life.
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
only involve filtration (screening) to remove debris,
sand and/or silt in the cooling water supply. However,
chemical treatment methods may be necessmy, in
55