Method for checking the leakproofness of safety valves

A method for checking the leakproofness of two controllable valves, wherein the valves are disposed at opposite ends of a test volume, wherein an inlet pressure pe is present upstream of the test volume, in front of valve VI, and wherein an outlet pressure pa is present downstream of the test volume, behind valve V2, where pe>pa and wherein the pressure in the test volume is equal to pz,

• wherein a control device triggers the valves for the opening and closing and wherein the control device is coupled with at least two pressure switches which are both in an operative connection with the test volume for the pressure monitoring,
• wherein:
• setting the first pressure switch to a first triggering threshold d1, wherein d1=pe/x where x≧3,
• setting the second pressure switch to a second triggering threshold d2, wherein d2=pe (1−1/x),
• wherein one of the following two groups of steps is alternatively executed with each leakproofness check:
• first step sequence:
• triggering of valve V1 in order to open the latter for a time period tL1 and then to close it,
• awaiting a measurement period tM1,
• checking the second pressure switch and abortion of the process with the recognition of the leakage of valve V2 if pz<d2,
• triggering of valve V2 in order to open the latter for a time period tL2 and then to close it,
• awaiting a measurement period tM2,
• checking the first pressure switch and abortion of the process with the recognition of the leakage of valve V1 if pz>d1;
• second step sequence:
• triggering of valve V2 in order to open the latter for a time period tL2 and then to close it,
• awaiting a measurement period tM2,
• checking the first pressure switch and abortion of the process with the recognition of the leakage of valve V1 if pz>d1,
• triggering valve V1 in order to open the latter for a time period tL1 and then to close it,
• awaiting a measurement period tM1,
• checking the second pressure switch and abortion of the process with the recognition of the leakage of valve V2 if pz<d2,
• indication of the functionality of the valves if no abortion of the process has taken place.