Freeze Protection
WINTERIZING THE PUMP STATION
1. The pump station is not designed or constructed to operate in freezing weather.
2. The recommended procedure for shutting down the station for the winter is as follow:
a. Turn all pump H-O-A switches to “OFF” position.
b. Turn all pump power disconnects to “OFF” position.
c. Isolate the pump station from the system with a valve not subject to freezing, or drain the system.
d. Isolate the inlet water supply, (booster stations only), with a valve not subject to freezing, or drain the inlet water supply.
e. Open all station isolation valves.
f. Open all other isolation and drain valves on the station. Open dual back-flush or Wye strainer blow-down valves.
After all gauges read “zero”:
Disconnect and remove all control valve hydraulic pilot assemblies. Store where there is no danger of freezing. Open control valve cover and bleed cocks. With a manual or electric pump, force into each control valve cover a mixture of ½ water and ½ antifreeze.
g. Disconnect the tubing and/or connections from each gauge or switchgauge or pressure switch.
h. Blow out each gauge sensing tube with compressed air.
i. Remove and drain entrapped water from gauges.
Besides the normal winterization procedures that are carried out on many irrigation systems, three (3) components of most variable frequency drive (VFD) pump stations require specific attention:
1. The heat exchanger has a water-filled coil that must be blown out with compressed air. Close the heat exchanger feed line isolation ball valve. Remove the inlet and outlet fittings allowing the inlet hose to drain. Using relatively low air pressure (less that 50psi), blow into the inlet expelling all water from the coil outlet. Replace the fittings and hoses. This is a good time to disassemble and clean the regulator and solenoid valve.
2. Isolate the pressure transducer sensing line using the ball valve typically provided on the system manifold. Remove the sensing line from the pressure transducer fitting. Leave the line disconnected until the freezing condition has passed.
3. The relief valve is best protected by removing the piloting entirely and placing it in a freeze protected area. Otherwise, the entire valve can be removed and likewise protected. This is a good time to service the valve by disassembling and cleaning its components. It is a good idea to have a repair kit on hand before disassembling the valve. If the valve is left in place, the water that is trapped under the cover must be purged by loosening the cover nuts and allowing the water to escape.
4. Remove any submersible pumps or drain their discharge lines by siphoning trapped water remaining in the column pipe. This should be done with suction lines as well, where a foot valve has trapped water in the column pipe.
Remember, it can and does freeze almost anywhere. Plan for freezes before they happen and damage expensive, essential components.
