While column rejoining in the water pipe line, initially at low velocity, the air is released through big orifice.

While column rejoining in the water pipe line, at higher velocity in the later stage, the large orifice is get closed at a pre-setted pressure of 0.1 Kg/ Sq.cm and the air is released through small orifice.

This phenomena induces a high non slam air cushion valve resistance inside the pipeline and reduces the velocity of water column.

After column is rejoined in the water pipe line, the large ball seals the large orifice.

This prevent the water hammer due to water column rejoining while pump shut down or power failure at peaks of the pipe lines.