During a relay lay, a noticeable pressure drop occurs in a downstream segment despite normal upstream pressure. What is the appropriate action?

• A. Increase upstream pump speed without other checks
• B. Close the downstream valve to stop flow
• C. Reassess and balance the system by adjusting pump pressures based on friction losses in each segment
• D. Replace hoses in the field

Answer: (C)

When a relay lay shows a pressure drop downstream while upstream pressure remains normal, the issue is not a single pump’s failure but an imbalance in how pressure is being distributed across the hose segments. Friction losses grow with flow and hose length, so the front portion can rob the downstream segments of pressure. The correct action is to reassess the system and balance it by adjusting each pump’s discharge pressure to offset those friction losses in its segment. This keeps the nozzle pressure at the desired level throughout the lay and prevents overloading any one section.

In practice, you estimate or measure the friction losses for each segment (consider hose size, length, fittings, and flow) and then set the pumps so that each discharge point contributes just enough pressure to overcome its segment’s losses while delivering the target nozzle pressure at the end. Increasing the upstream pump speed without adjusting the rest simply shifts pressure and can worsen the imbalance. Closing the downstream valve stops flow and doesn’t fix the underlying balance, and replacing hoses isn’t a justified response to this pressure distribution issue.