Cleveland steamcraft 21-CET-8, Service Manual

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Model 21 -CET-8 Service Manual Page 73
During shutdown, the 3 -minute timer controls the fill and rinse solenoids. Setting
the ON/OFF switch to OFF starts the 3-minute timer and energizes timer terminals
2-3. The timer contacts dose, opening the fill valve for steam generator blowdown
and the rinse valve to flush the float cylinder. After 3 minutes, the contacts of the
timer open to remove power from the fill and rinse solenoids, dosing the valves.
The rinse solenoid valve controls water flow to the float cylinder during generator
blowdown. The rinse solenoid operates only with the ON/OFF switch in the OFF
position. The 3 -minute timer controls operation of the rinse solenoid valve. Refer to
3-minute timer text above.
During steaming operations, sediment collects in the float cylinder. Sediment build
up in the cylinder impedes smooth operation of the floats as the water level rises
and falls. The rinse flow flushes sediment from the cylinder that collects during
operation. Without this rinse, sticky float operation will cause improper water levels,
heater burnout, and other malfunctions and damage.
The drain solenoid valve controls water flow from the steam generator to the
condenser.
• During normal steaming operation, (ON/OFF in the ON position), the drain
solenoid is energized dosing the drain valve. Water does not drain from the
steam generator.
• At shutdown (ON/OFF switch OFF) the solenoid deenergizes, the valve opens,
and the generator drains.
The fill solenoid valve controls water flow into the steam generator. The valve opens
and closes as the water level fluctuates in the float cylinder and generator. During
steaming operations, the fill valve cycles approximately two to five times each
minute.
• While the water level in the float cylinder is below the upper limit, the high level
float switch is dosed. This energizes the solenoid, which opens the valve.
• When the water level in the float cylinder reaches the upper limit the high level
float switch opens. This deenergizes the solenoid, which doses the valve.
The valve operates at a maximum water pressure of 60 psi. Higher pressures cause
unnecessary valve wear and require frequent valve replacement. If necessary,
install a pressure regulator set at 50 psi.
Printed 12/90
3-Minute Timer
(14, Figure 6-5)
Rinse Solenoid Valve
(1, Figure 6-11)
Drain Solenoid Valve
(4, Figure 6-12)
Fill Solenoid Valve
(1, Figure 6-11)