How do you prepare a 12-volt diaphragm pump system to survive winter storage requirements?

Tru Mark uses a Shurflo 3.3 GPM 12-Volt pump unit (for E-100 and RS-500 field marking models) and a Shurflo 1.46 GPM 12-Volt Pump (for EZ-70). The Shurflo technical services representative suggests using RV style antifreeze liquid. That is a propylene glycol liquid. Dow Chemical manufactures DOWFROST RVR that would be suitable.

Prior to this storage step we would also recommend running a "pump protector" or "pump saver" through the system. This should be done on a routine basis. You can find this in 32 oz. plastic bottles at a good paint store that sells commercial paint sprayers. I would add 1 to 2 oz. of the pump protector to a gallon of water and run it through the system for a couple minutes. This helps keep any remaining paint in suspension and flushed during the rinse process. We suggest unhooking the hose connectors at the pump head to and allow any excess water run out of the pump head. One key to successful subsequent operation is keeping the internal pump head wet so the valve kit supports quick pump priming operations.

Another option is to remove the pump valve and diaphragm kits from the motor (3.3 GPM pump). Remove the 6 Phillips screws from around the edge of the pump head and the diaphragm kit with valve kit will slide off the motor shaft. In the spring when you put the kits back in all you need to do is spray some water into the pump head before you attach the hose connectors.