High reliability pressure relief valve

A method of producing a high reliability pressure relief valve for use in a deep sea environment comprising the steps of:

• assembling a first stage with a first pressure relief valve for relieving interior fluid pressure from an enclosed housing above a first cracking pressure value;
• assembling a second stage with a second pressure relief valve to relieve the interior fluid pressure above a second cracking pressure value;
• assembling the first stage with the second stage in series, with an enclosed cavity between the first stage and the second stage, where the first stage relieves the interior fluid pressure above the first cracking pressure value from the enclosed housing into the enclosed cavity, and where the second stage relieves the interior fluid pressure above the second cracking pressure value from the enclosed cavity into the deep sea environment outside the enclosed housing,
• wherein the first stage and the second stage can withstand at least 300 psi external fluid pressure from the deep sea environment;
• wherein the first pressure relief valve includes a first poppet with a first poppet seating surface having a first flat portion, and wherein the first pressure relief valve includes a first body with a first body seating surface having a second flat portion, and wherein the first flat portion and the second flat portion are opposing, and wherein the first pressure relief valve includes a first valve seal between the first poppet seating surface and the first body seating surface.