Schulz SRP 3040E Manual De Instrucciones página 47

WORKING PRINCIPLES
2. Air Flow
When the motor is started, power is transmitted to the air end by pulleys and belt.
The rotation of the screws creates a vacuum and the air production cycle begins when suction occurs.
The [atmospheric] air flows through filter (item ) and enters the air end (item ) [radially] through the hole
located in the inlet control valve (item ). Air compression [axial] is accomplished as air is forced between the
flutes of the screws (rotors) and the air end housing. Air is then forced through the discharge port.
During this start sequence, the air end is lubricated by residual oil (See Oil Flow description, page 46).
Air suction through the partially opened inlet control valve does not require the full power of the motor.
Initial air compression at start-up (minimal pressure) and the minimum pressure check valve facilitate the
rapid pressurization of the air/oil tank (item ) causing, by positive pressure, the flow of lubricoolant (item )
into the air end.
The compressed air and residual oil then passes through the separator element (item ). Due to the
selectively restrictive nature of the filtering media the air flows freely through the element and the oil loses its
velocity and falls to the bottom of the oil separator (item ).
In a few seconds the internal pressure of the tank rises to 3.4 to 4.1 bar [50 to 60 psig], the motor is operating
at its' nominal rotation and the air can be introduced and compressed at full capacity with the inlet control
valve (item ) completely open. It is at this point that the wye-delta starting system introduces full voltage to 2
the electric motor.
At the discharge of the compressing unit, the inlet air, mixed with lubricant oil, is introduced tangentially and at
high velocity into the tank. Here it the centrifugal force separated the [denser] oil from the air. Due to its
density, the oil settles to the bottom of the tank.
With the inlet control valve totally open and the air being compressed at full capacity, the pressure in the tank
rises rapidly and overcomes the spring tension which maintains closure of the minimum pressure check
valve (item ) and the air passes through the after-cooler (item 8
The minimum pressure valve has the following functions:
A. Operates as a check valve, preventing system air from re-entering the compressor when the compressor
is off or modulated;
B. Maintains minimum pressure of about 3.4 bar (50 psig) to ensure adequate lubrication;
C. Maintains minimum oil pressure to prevent inappropriate oil consumption rate.
1
2
FIGURE 10 - AIR END IN WORK
4
7
3
12 )and into the compressed air network.
5
6
45