Verification of the hydraulic behavior of air blockers used in water supply systems

For various reasons, it is possible the presence of air in the water supply pipes and, consequently, that air volumes are counted by the hydrometer. This phenomenon, in addition to occurring in Brazil, is also present in countries such as Puerto Rico, Peru and Mexico. There are for sale in the Brazilian market equipment called “air blockers” which, according to the manufacturers, prevent the improper billing. However, to date, there is no specific standard or consolidated literature for admeasurement and certification of such devices. In this context, the objective of this work was to verify the hydraulic behavior of the air blockers, in order to serve as a basis for future discussions among users, manufacturers and supervisory bodies on the adequate use of these equipments. In the experimental tests performed, the load loss versus flow curves were obtained for five types of blockers. As a complement, a computational modeling allowed to verify the possible effects caused in the water supply. The results showed a large variation of the values of minimum pressure necessary for flow to occur, from 0.92 to 8.60 m.c.a., as well as the load loss curves, meaning, in some cases, a drastic reduction of the water flow rate. As a main conclusion, it was observed that a regulation of these devices is required to enable the elaboration of instructions on the correct sizing and use in each situation.