Pilot operated pressure/vacuum vent for a fuel storage tank

A pressure/vacuum vent mountable to a vent pipe of a, storage tank, the vent having a valve housing having a wall defining a chamber which is in fluid communication with said storage tank, and including a first valve responsive to an over-pressure condition of a first pressure, a second valve responsive to an over-pressure condition at a second pressure, said first and second valves comprising poppet valves, and said poppet valves being biased to a closed position, and a third valve responsive to an under-pressure condition, said first and second valves each being movable from a closed position to an open position to dissipate excessive pressure in said storage tank, said third valve being a diaphragm valve, said diaphragm valve including a vent housing, a valve body mounted in the vent housing, the valve body having a first side and second side, a diaphragm mounted to the valve body first side in spaced relationship from a surface of the first side to define a diaphragm valve, chamber, a mechanical spring located in said diaphragm valve chamber, a first passage in the valve body extending between the first and second sides of said valve body, said first passage opening into said diaphragm valve chamber, a second passage extending between said first and second sides of said valve body externally of said diaphragm valve chamber, and said third valve being movable from a closed position to an open position to dissipate a vacuum in said storage tank, and a lever arm having first and second portions, said lever arm's second end portion closes said second passage, and said first end portion defining a pivot point to effect lever movement, said lever arm being operatively connected to said diaphragm and arranged externally of said diaphragm valve chamber, such that movement of said diaphragm in a first direction will lift said lever arm off of said second passage, and movement of said diaphragm in a second and opposite direction will return said lever arm to said second passage such that said lever arm covers said second passage, said first and second pressures are different, said first pressure being greater than said second pressure, said first valve enabling greater rat of escape of gases when in its opened position than des said second valve, the pressure/vacuum vent including a vent housing, said valve housing being received in said vent housing, said vent housing including a side wall and a bottom wall, said bottom wall having an opening therein through which a bottom portion of said valve housing extends, said bottom wall sloping downwardly towards its side wall, and having drain holes therein.