Inertial resistance: Flow does not stop immediately → Overfeeding
Here, let's review the functions of a ball check valve in a diaphragm pump.

This chart shows that, as long as the pump is functioning normally, the discharge side and suction side do not open and close at the same time.
However, because of pulsation, both sides may be open under certain conditions.

Law of Inertia

An object in motion stays in motion--this behavior is called inertia.
A moving object continues moving while an object at rest stays in that state. The exact same can be said about liquid. Does the liquid in the pipes stop at the same time the pump stops discharging?
According to the law of inertia, a body of liquid does not stop unless acted upon by another force in the direction opposite to the direction of the motion (this is called back pressure).
So, what happens when it doesn't stop?

This phenomenon is called overfeeding.

In order to prevent overfeeding, another force (back pressure) must be applied to stop the movement of the liquid. A typical way to do this is by installing an anti-siphon check valve or a back pressure valve at the tip of the discharge-side hose (piping).

TACMINA's Smoothflow Pump is a diaphragm pump with no pulsation, which relieves it from the impact of inertial resistance. Be completely free from the problem of overfeeding.
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