There are two types of piping resistance, both of which are expressed by pressure: frictional resistance and inertial resistance.

Frictional resistance is generated from the friction between a liquid and the walls of the piping. The greater the viscosity of the liquid, the longer the pipe, and the more the piping bends or includes piping equipment (such as valves), the greater the frictional resistance will be.

Inertial resistance is defined as any force that works against a liquid’s tendency (inertial force) to remain in motion (if already in motion) or standing still (if not in motion). In liquid transfer, the inertial resistance can be indicated by pressure, but for general-purpose metering pumps that produce pulsation, the inertial resistance will be greater the smaller the piping bore is or the longer the piping is. Conversely, if the opening diameter of the piping is doubled, the resistance will be 1/4. Because Smoothflow Pumps have no pulsation, there is almost no inertial resistance except at startup.

Use the Pressure Loss Calculator to calculate the theoretical value of piping resistance when using a TACMINA pump.