Water and Sewer Vent Valves

Relief valves (or vents) are hydraulic devices that ensure the regularity of the flow by venting air from pressurised pipelines. Vent valves are usually installed at the highest points of the longitudinal profile where air tends to flow. This is done to prevent the presence of air inside the pipe. The problems that can arise are:

-decrease in the outflow section and thus reduction of the water flow rate;
– decommissioning of the pumps in the preemptive pipelines;
– corrosion inside metal pipes.

There is usually about 2% air in the water used in distribution. As pressure decreases and temperature rises, the percentage of air decreases and consequently there will be a constant production of free air expanding in the pressure ducts. Vent valves have the function of air control and management. Vent valves can perform the following functions:

– degassing: the function of removing air;
– volumetric emptying: a large volume of air enters and compensates for the volume of liquid leaving. This avoids dangerous depressions;
– volumetric filling: air present exits to prevent air pockets forming;

The best choice for good operation are cast iron air release valves, as they are reliable, simple and durable and therefore do not require much maintenance.