How to Prevent Drummond Pump Prime Cap Failure

Many of our customers have found that the plastic prime cap on the 3/4" HP pump included with the mixing station can break off from the pump, a catastrophic failure which can lead to significant chemical exposure and loss of product. Understanding of this issue is rapidly evolving, but we believe it is caused primarily by chemical dissolving the plastic priming cap, allowing even moderate pressures to induce failure.

Thus, there are a handful of simple steps which can be taken to resolve this issue:

1. Do not run dry. Always ensure there is fluid moving through the pump.
2. Do not deadhead. "Deadheading" is a term used to describe running a pump without fluid moving through it. This WILL cause the fluid "stuck" in the pump housing to rapidly heat, and eventually boil. The additional pressure added by this steam can damage the pump's impellor, and can destroy attached plumbing components, including the prime cap.
3. Open the recirculation valve to 45 degrees. The included 3/4 HP pump is able to run at up to 40 PSI. However, reducing the pressure of the plumbing system reduces the chance of catastrophic failure. Thus, we recommend to open the recirculation valve to 45 degrees, which will reduce the pressure to 20 PSI but, in our testing, only resulted in a 2 GPM drop in flow rate to the drone. 
4. Replace plastic cap prime cap with brass. The prime cap is 1/2" MPT thread. Brass is chemical and pressure resistant, and is much less likely to degrade under the harsh chemical conditions involved in drone spraying. This part is being offered to all mixing station owners. If you are a current owner of a mixing station and would like to receive this part, please fill out the following form.

Pump Cap Replacement Form