? Working principle- the flow through the nozzle creats a vacuum at the valve seat. Air is drawn in through  the sensing port at  the tip of the spout, through the safety cut out, past the diaphragm,and into the fuel. the valve will remain open while the air flows freely. When the fuel reaches the sensing port, suction builds up rapidly until it lifts the diaphragm and trips the automatic action  which shuts the valve.the mechanic also trips if the ball of the safety cut off rolls back to obstruct the free air flow.It will also occur if the spout is pointed  upwards or if the nozzle is dropped onto the ground. the valve opens with the flow, allowing smooth low  control  for"to-the penny" dispensing. It closes against the flow for a soft shock-less closure.

? All type of guards are available if requested.
? All type of guards with block magnet are available if requested.
? "ZVA" logo or blank are available.  
? 100% Factory tested.