Gear pump is a positive displacement pump. This means that the movement of the fluid (product) occurs due to a change in the volume of the working chamber.

Accordingly, the operating principle leads to the following conclusion — the flow rate of such a pump must not be regulated by closing shut-off valves on the discharge line.

When closing the valve on the discharge line, the following situations may occur:

• damage to the gears

• seal leakage

• coupling damage

• electric motor burnout

In the images below, you can observe the current consumption when the pump operates with an open line (left image) and when attempting to close the valve (right image).

When the valve is closed, the current immediately increases.