Double isolation for double chamber differential pressure meter

A double chamber differential pressure meter comprising:

• an axial fluid circulation conduit adapted to allow a flow of a fluid to be measured, the axial fluid circulation conduit comprising a first cross-sectional area;
• a plate adapted to fit in the axial fluid circulation conduit, the plate comprising an orifice having a second cross-sectional area smaller than the first cross-sectional area;
• a chamber coupled to the axial fluid circulation conduit by a communication passage, the chamber being adapted to hold the plate, the communication passage being adapted to allow the plate to move between the axial fluid circulation conduit and the chamber, the chamber further comprising an opening adapted to allow the plate to be removed from the double chamber differential pressure meter;
• first and second closure elements disposed between the axial fluid circulation conduit and the chamber, wherein:
• the first closure element comprises a first housing and a first plate valve disposed in the first housing, the first housing comprising first and second openings defining a first portion of the communication passage, the first plate valve having a first side and a second side opposite the first side, the first plate valve adapted to linearly move from a first position within the first housing in which the first plate valve does not interfere with the communication passage to a second position within the first housing in which the first side of the first plate valve is adjacent to and covers the first opening and the second side of the first plate valve is adjacent to and covers the second opening, thereby interrupting the communication passage;
• and
• the second closure element comprises a second housing and a second plate valve disposed in the second housing, the second housing comprising third and fourth openings defining a second portion of the communication passage, the second plate valve having a third side and a fourth side opposite the third side, the second plate valve adapted to linearly move from a third position within the second housing in which the second plate valve does not interfere with the communication passage to a fourth position within the second housing in which the third side of the second plate valve is adjacent to and covers the third opening and the fourth side of the second plate valve is adjacent to and covers the fourth opening, thereby interrupting the communication passage.