Vital for sub-surface installations, allows air to escape the pipline to help prevent water hammer or blockage, also allows air to enter the lines at shutdown to prevent suction of dirt into the system.
To ensure optimal performance of sub-surface installation, it is important to include an air/vacuum relief valve. The valve will allow air to escape the pipeline, thus preventing water hammer or blockage. The valve will also allow air to enter the lines as water evacuates the lines at shutdown. This prevents vacuum suction of dirty water from occurring.