Air-Operated Diaphragm Pump, 13 GPM Capability, 1/2 Inch NPT Ports,

Stalling mid-cycle is exactly the kind of issue that unbalanced air valve design addresses. Most diaphragm pumps that stall do so because the valve loses the pressure differential it needs to shift. The patented unbalanced air valve on this ARO unit is built specifically to restart pumping action reliably when called upon, so dead-stall situations are far less likely to leave you stuck mid-job.

Bolted construction provides a superior seal, making it safer for handling various fluids, though extremely viscous fluids will reduce flow rate.