Armstrong Pumps offers the dualArm pump, an upright design that combines the performance advantages and features of two Armstrong Vertical In-Line pumps in a single casing. The dualArm design provides a built-in backup feature incorporating two volutes, two motors and two impellers sharing common suction and discharge ports. The arrangement allows for parallel or standby operation, eliminating system service shutdowns and the need for air purging. The unit features a small footprint and a unique casing design that allows tandem operation.Armstrong Pumps.