Water hammer happens when a rapid change in flow velocity creates a sudden pressure surge in the piping. Opening discharge valves too quickly lets the water slam into the valve and downstream piping, causing shock waves that can damage equipment and joints. Prevent it by easing valve operation: open valves gradually and smoothly, so the flow ramps up rather than jumps to full speed. Keep the pump running at a steady speed to maintain a gentle, continuous increase in flow, avoiding abrupt throttle changes. If multiple discharge lines are involved, open them in a controlled sequence rather than all at once, so each line adds flow without creating a large simultaneous surge. In short, slow, controlled valve openings and coordinated sequencing minimize velocity spikes and protect the system from water hammer.

Inspecting suction strainers matters because they keep debris out of the pump suction. If debris blocks the strainer, suction can be restricted, which can lead to loss of prime and reduced flow. A loss of prime means the pump can’t stay fully filled with water, causing startup or running issues. The restricted flow and pressure drop can also create conditions that promote cavitation, which damages the pump. So the main reason to inspect is to remove debris, keep the suction path clear, and preserve prime to prevent flow problems that could lead to cavitation. Strainers don’t inherently prevent cavitation by themselves—cavitation depends on pressure, vapor pressure, and overall system hydraulics—so saying they prevent cavitation outright isn’t accurate.

Before moving a deck gun into a structure fire, the primary safety step is to verify that no personnel are in the path of the discharge. The high-velocity water stream can injure firefighters or knock them off balance, and anything in its line of fire can be struck unexpectedly as you adjust aim or reposition the gun. Establishing that the stream will not cross anyone’s position directly protects crews in the vicinity and prevents serious injuries. While keeping the path clear, selecting the right nozzle setting and establishing a safe operating range are important for effectiveness and control, they don’t address the immediate hazard of someone standing in the line of fire. If someone were in the stream’s path, the other precautions wouldn’t prevent an injury until they’re moved out of the way.

When you see a significant drop in discharge pressure while you’re holding the throttle, focus on finding and fixing the real source of the loss rather than trying to push harder. Systematic checks should include looking for air leaks in suction or discharge lines, valve positions that aren’t fully open, clogged lines or filters, and any sudden increase in downstream demand. As you identify a source, correct it while keeping the pump operating within safe limits. This approach addresses the actual cause of the pressure drop, helps prevent equipment damage, and maintains safe operation. Masking the problem by increasing throttle can overstress the pump and piping, shutting down the pump isn’t necessarily the right move unless there’s a hazard, and simply adding prime water won’t resolve a loss of pressure caused by leaks, blockages, or high demand.