Triplex Pump

Triplex pumps use three reciprocating pistons or plungers to draw water in and push it out at high pressure. The three-cylinder design provides smoother pressure output than single or duplex pumps because the overlapping pressure strokes minimize pulsation. This results in a more consistent water stream at the nozzle and less stress on the high-pressure plumbing system.

Common triplex pump specifications on hydrovac trucks include flow rates of 5 to 18 gallons per minute (GPM) at pressures of 1,000 to 3,000 PSI. The pump is driven by the truck engine through the PTO, by a hydraulic motor, or by a dedicated auxiliary engine. Variable flow and pressure control allow the operator to adjust water output to match soil conditions and proximity to utilities.

Triplex pump maintenance includes regular inspection and replacement of packing seals, valves, and plungers, which wear due to the abrasive nature of the water and any particulates that pass through the inlet strainer. A cracked plunger or worn packing seal will cause a loss of pressure and flow. Most manufacturers recommend rebuilding triplex pumps at intervals of 500 to 1,000 operating hours.