Pilot valve for pressure relief valve

A valve assembly comprising:

• a) a pressure relief valve including a poppet operated by a diaphragm, the diaphragm defining an upper diaphragm chamber and a lower diaphragm chamber within a housing of the pressure relief valve;
• b) an orifice extending between the upper and lower diaphragm chambers;
• and
• c) a pilot valve assembly in fluid communication with the upper diaphragm chamber and atmospheric pressure, the pilot valve assembly including:
• i) a first pilot valve, defining a first pilot valve passageway between the upper diaphragm chamber and atmospheric pressure, arranged to open only when a predetermined positive pressure differential exists between the upper diaphragm chamber and atmospheric pressure, wherein when in the open position, the pilot valve assembly blocks the orifice;
• ii) a second pilot valve, defining a second pilot valve passageway between the upper diaphragm chamber and atmospheric pressure, the second pilot valve passageway being separate from the first pilot valve passageway, the second pilot valve being arranged to open only when a predetermined negative pressure differential exists between the upper diaphragm chamber and atmospheric pressure.

A valve assembly comprising:

• a) a pressure relief valve including a poppet operated by a diaphragm, the diaphragm defining an upper diaphragm chamber and a lower diaphragm chamber within a housing of the pressure relief valve;
• b) an orifice extending between the upper and lower diaphragm chambers;
• and
• c) a pilot valve assembly in fluid communication with the upper diaphragm chamber and atmospheric pressure, the pilot valve assembly including a first pilot valve arranged to open only when a predetermined pressure differential exists between the upper diaphragm chamber and atmospheric pressure, wherein when in the open position, the pilot valve assembly blocks the orifice.