KROHNE H250 M9 Safet V2 EN - Manual (Page 9)

LIFE TIME / PROOF TESTS
6
9
H250 M9
www.krohne.com 06/2013 - 4000656702 MA H250-M9 SIL R03
6.2 Proof tests
Possible proof tests to detect dangerous undetected faults
Proof test 1 Proof test 1 Proof test 1 Proof test 1 consists of the following steps:
1. Take appropriate action to avoid a false trip.
2. Force the variable-area flowmeter H250/M9 to reach a defined “MAX” threshold value and verify
that the inductive limit switch goes into the safe state.
3. Restore the loop to full operation.
4. Restore normal operation.
Proof test 2 Proof test 2 Proof test 2 Proof test 2 consists of the following steps:
1. Take appropriate action to avoid a false trip.
2. Force the variable-area flowmeter H250/M9 to reach a defined “MIN” threshold value and verify
that the inductive limit switch goes into the safe state.
3. Restore the loop to full operation.
4. Restore normal operation.
INFORMATION!
Both tests together will detect approximately 90% of possible "du" failures.
INFORMATION!
It is necessary to open the casing of the device in order to do the electrical connection and to set
the limit switch set points.
Special attention is required when the casing is open. Avoid a deformation of the precision
Avoid a deformation of the precision Avoid a deformation of the precision Avoid a deformation of the precision
mechanics indicator system. mechanics indicator system. mechanics indicator system. mechanics indicator system. By deforming the pointer or the balance vane the ease-of-
movement can be influenced leading to a wrong measurement.
By performing the mandatory proof-test after installation and closing the casing the ease-of-
movement has to be verified
MA_H250_M9_SIL2_R03_en_656702_PRT.book Page 9 Wednesday, June 26, 2013 9:08 AM