When starting up a positive displacement sludge pump, what should be done with the suction and discharge valves?

When starting up a positive displacement sludge pump, having both the suction and discharge valves open is essential to facilitate proper operation. Positive displacement pumps are designed to move a fixed volume of fluid with each cycle, which means they need to have proper access to the sludge from the suction line while also allowing the pumped sludge to exit through the discharge line.

Opening both valves ensures that the pump can draw in the sludge without creating a vacuum or causing cavitation, which can occur if the suction valve is closed or partially closed. At the same time, having the discharge valve open allows the pumped sludge to flow out freely, preventing pressure build-up within the pump that could lead to equipment damage or operational inefficiencies.

If either the suction or discharge valve is closed during startup, it could hinder the pump's ability to operate properly, leading to potential air-locking or damage due to excessive pressure. Thus, starting the pump with both valves open is the correct procedure to ensure smooth and efficient operation.