Optimizing Pump Suction and Discharge Piping

Carac. Line Negative Suction

The suction pipe must be designed to ensure smooth pump functioning. It should be straight, tight, and as short as possible to prevent air entry. Avoid sudden widening or narrowing; use eccentric cones with the wider end horizontal. Avoid elbows in planes adjacent to other elbows.

When selecting the proper pipe diameter, consider head losses and maximum speed. Use tables to calculate the most suitable pipes for operating conditions.

Always mount the suction pipe in an upward position towards the pump to prevent air accumulation, which can reduce capacity and cause pump issues. Horizontal sections should have a slope of at least 2% and a sufficient straight length to stabilize liquid flow.

A foot valve should be mounted at the lower end of the suction pipe, at an appropriate depth, to prevent air entry. Never place the suction inlet near the bottom to avoid aspirating sludge. The foot valve can be omitted only in self-priming pumps that do not require priming.

Install a gate valve near the pump for shut-off in case of failure and for low-pressure drop when fully open.

Discharge or Drive Line

The discharge line should be as short and direct as possible to minimize pump head. Use standard or large radius elbows whenever possible.

A check valve should be mounted on the discharge piping. In systems with high pumping pressures, install a check valve to contain the water column in the discharge pipe during a sudden pump stop or power failure. This prevents water hammer, which can damage the pump.

The gate valve will be mounted at the pump outlet to regulate flow. When open during service, it helps break up the fluid and can be used to stop the pump when necessary.

Pipe size should be chosen based on permissible speed or load losses. Pressure drop increases with speed. Higher flow rates require more pump power and energy. Larger pipe diameters increase initial cost but reduce energy consumption.