Leaking Check Valves

1. Inspect, clean, and replace diaphragms for swelling or abrasions on the diaphragm seat.
2. Inspect all connections for tightness. If joints are not sealed tightly air leaking into the check valve will break the suction and allow fluid to leak.

Leaking Check Valves with Drop tubes

Drop tubes are similar to a straw filled with fluid. If a finger is held tightly over one end the fluid it will remain in the straw. However, if there is the slightest leakage the fluid will drain from the straw. With drop tubes the trick is to keep the fluid in the tube without allowing air either at the top end or from the spray tip end to developing a channel allowing the fluid to escape. If they leak while flying be sure the discharge tube is parallel to the airflow.

Leakage around the center of the Check Valve or trouble reassembling the Check Valve after servicing the screen.

Replace the Viton Seal Part No. 10-040

On-Off Check Valves. Leakage out the front of the Check Valve

Loosen the screw and apply RED LocTite to screw and retighten. With the check valve attached to the spray boom the check valve should rotate smoothly with some effort. If the check valve still leaks disassemble, clean, inspect, and replace worn parts.

Screens Plugging

The check valve screens are 20 Mesh while the boom strainer on the aircraft is 30 mesh. This means that the check valves should operate all season without cleaning because the hole size on the screens are larger then the hole size on the boom strainer. If the screens are plugging then the boom strainer needs to be serviced and the screens measured to determine if it is long enough to seal at the front of the strainer.