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Heat Exchanger Fan/Motor and Starter - The combination axial fan/motor (two units on VS50 and
VS70, one unit on VS45) provides cooling air for the heat exchangers and electronics box. The starter
provides control and overload protection for each fan motor. Overload heaters should be selected and
adjusted based on the motor nameplate amps and the instructions located inside the cover of the
electrical box. These devices are designed to operate with 3 ph-60 Hz-460 vac electrical power – the
necessary electrical wiring has been provided.
Main Motor Ventilation Fan/Motor and Starter – The combination axial fan/motor cools the main motor
by blowing fresh air over its body. The starter provides control and overload protection for fan motor.
Overload heaters should be selected and adjusted based on the motor nameplate amps and the
instructions located inside the cover of the electrical box. These devices are designed to operate with 3
ph-60 Hz-460 vac electrical power – the necessary electrical wiring has been provided.
Control Transformer - This device reduces the incoming power voltage to 110-120 volts for use by
various control components (e.g., 24 vdc power supply, electrical enclosure cooling fans, etc.). Two
primary fuses and one secondary fuse are provided for overload protection.
Power Supply (24vdc) - This device supplies electrical power to the AirSmart controller and various
solenoid valves.
For Letter References A thru U below, see Figure 4-2, page 30.
Inlet (Poppet) Valve (B) – This device is located at the intake flange of the compressor. During
compressor operation, the underside of the poppet is vented to atmosphere via a 3-way solenoid valve,
allowing the poppet to fall [open] and feed fresh air to the compressor inlet. During stopped operation
modes (e.g., commanded from keypad or initiated by protective shutdown), the 3-way solenoid valve
feeds an air signal to the underside of the poppet, forcing it upward [close] and block off the compressor
intake. This prevents trapped air and oil within the compressor from exiting through the inlet filter. See
SECTION 10 for further details.
Minimum Discharge Pressure/Check Valve (G) – This device maintains a minimum pressure [80psig]
within the air/oil reservoir, thus insuring (lubrication/cooling) oil injection flow into the compressors. It also
prevents the back flow of compressed air from the customer’s piping back into the compressor package
when the compressor is not running. See SECTION 9 for further details.
The spring-loaded [and pneumatically assisted] piston does not allow the discharge of compressed air
from the air/oil reservoir until the compressor builds up reservoir pressure beyond 80 psig. Beyond this
pressure level, the valve remains fully open.
Oil Mixing Valve (L) – This device prevents the compressor from operating at a pressure and
temperature combination that condenses water vapor in the oil system. The servo-driven, 3-way, ball
valve mixes cooled and hot oil, prior to delivery to the oil filter and oil injection line, as commanded by an
algorithm residing in the package controller. See SECTION 5 for further details.
Pressure Relief Valve (O) – This device protects the pressure containing components of the compressor
package against high pressure exceeding 188.5 psig. See SECTION 11 for further details.
Pressure Regulator (S) – This device supplies the pneumatic signal to actuate the minimum pressure
valve [G]. The regulator is adjusted to achieve an opening pressure at the MPV of 80psig.
Inlet Feed Valve (C) - This (three-way solenoid) device supplies/vents the required pneumatic signal to
actuate the inlet poppet valve. When energized, it opens [vents] the inlet poppet valve and when de-
energized, it closes [pressurizes] it.
Ball Valve – Oil Drain (N) - This device allows the drainage of the oil charge held in the reservoir during
oil change operation.
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