Lesson 2: Meter types – Water prepayment meters

Water meters are generally divided into two types – single unit consisting of meter & valve and meter with a separate valve. Although there are water prepayment meters that are integrated (similar to their electricity counterpart), where the keypad forms part of the meter, these are generally not used in our region.

Some meters include a one way valve, a strainer (filter) and/or a manual shut-off valve. During installation direction of water flow must also be observed. This is usually indicated on the meter body.

Other considerations noticed in the field are the types of valves used and the measurement method. Some valves require a certain minimum water pressure to operate and may use a flapper-type shut-off valve, which is susceptible both to minimum pressure requirements and ingress (dirt), both conditions may lead to faulty valve operation. A ball-valve may be more appropriate under these conditions, however there are considerations such as required power to rotate the ball-valve and more moving parts that may fail. Regarding the measurement method – most meters make use of impeller-type measurement, with it’s associated drawbacks (these are covered in the basic technical meter training; clearly a non-intrusive method, such as ultrasonic measurement would always be the preferred option. As always it is a price versus quality consideration.