Fluid velocity also plays an important role in permanent pressure loss. The faster the fluid is moving, the greater the pressure loss. Therefore, a permanent pressure loss value must always be associated with a certain flow rate. Meter manufacturers often state the permanent pressure loss at the maximum stated velocity of the meter. There are many different meter types and all have different characteristics of permanent pressure loss.
Some meters have no restriction in the pipe, so therefore no permanent pressure loss.
In other words, they incur the same loss as a straight piece of pipe. For example, magnetic meters and ultrasonic meters generally have no permanent pressure loss. Other meters have a very high loss. These meters have physical restrictions due to the nature of the meter. Examples of high loss meters include curved-tube type coriolis flowmeters and positive displacement meters.