Tank to Pump

Pump Operations

Relay Pumping

Relay pumping is moving water over a long distance by chaining engines, each one boosting the pressure for the next. It overcomes the friction loss that would otherwise bleed a single long supply line dry.

A relay schematic: a source pump on the left feeds a long supply line of large-diameter hose to a receiving pump on the right, with an intake readout between them. Two horizontal pressure bars below compare the supply discharge pressure the source pump must produce against the pressure surviving at the downstream intake. As the lay lengthens, the intake bar shrinks toward the target floor and its status shifts from above-floor to approaching-floor to below-floor.

Relay pumping · interactive

ABOVE FLOOR40 psi intake vs 20 psi targetThe downstream pump's intake sits comfortably above the target residual. The source engine is beating the friction loss of this leg with margin to spare — a sound relay length.

  • Source PDP held120
  • Supply FL this leg80
  • PDP to hold target100

Each pump re-boosts from its OWN intake. The next engine takes its 40 psi intake and adds 80 psi to reach 120 psi again — so the line carries about 120 psi between pumps, not about 240 psi. Relay pumps re-pressurize from their intake; they don't stack discharges on top of one another.

Pumpers in a relay work in series — each one only beats the friction loss of ITS leg plus the intake floor at the next engine (20 psi here, the never-go-below target). Holding the source discharge fixed at 120 psi, a longer leg drains more to friction loss, so the next intake sags while the PDP needed to hold the target climbs — computed by the same engine functions as the Relay Pumping calculator. These are training estimates; follow your SOPs.

Drag the distance between two pumpers in series and watch the downstream pump's intake sag as friction loss eats the supply leg — while the supply PDP needed to hold the target residual climbs in step. Each pump re-boosts from its OWN intake back to the relay discharge, so the line carries one discharge between pumps, not two summed — relay pumps re-pressurize, they don't stack.

Over distance, friction loss eats the pressure of even a large supply line. A relay breaks the run into legs: the source engine pushes to the next pumper, which receives water at a safe intake pressure and pushes it onward, and so on to the attack engine.

Planning a relay means keeping each receiving engine's intake above a floor so it never starves, while covering the friction loss of each leg. The longer the distance and the higher the flow, the more pumpers the relay needs.

Where this shows up

See also