KROHNE H250 M40 Safety V2 EN - Manual (Page 10)

6
LIFE TIME / PROOF TESTS
10
H250 M40
www.krohne.com 06/2013 - 4000904202 MA H250 M40 SIL R02 en
6.2 Proof tests
Possible proof tests to detect dangerous undetected faults Possible proof tests to detect dangerous undetected faults Possible proof tests to detect dangerous undetected faults Possible proof tests to detect dangerous undetected faults
Proof test for H250/M40/K* with inductive limit switches
1. Take appropriate action to avoid a false trip.
2. Inspect the device for any visible damage, corrosion or contamination.
3. Force the variable area flowmeter H250 M40 to reach a defined “MAX” threshold value and verify
that the inductive limit switch goes into the safe state.
4. Force the variable area flowmeter H250 M40 to reach a defined “MIN” threshold value
and verify that the inductive limit switch goes into the safe state.
5. Restore the loop to full operation.
6. Restore normal operation
It is assumed that the test will detect approximately 99% of possible dangerous undetected
failures.
Proof test for H250/M40/ESK with 4…20mA output
1. Bypass the safety PLC or take other appropiate action to avoid a false trip.
2. Perform 5-point calibration verification of the variable area flowmeter H250 M40.
3. Force the variable area flowmeter H250 M40 to go to the high alarm current output and verify
that the analog current reaches that value.
4. Force the variable area flowmeter H250 M40 to go to the low alarm current output and verify
that the analog current reaches that value.
5. Restore the loop to full operation.
6. Remove the bypass from the safety PLC or otherwise restore normal operation.
It is assumed that the test will detect approximately 99% of possible dangerous undetected
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_M40_SIL2_R02_en_904202_PRT.book Page 10 Wednesday, June 26, 2013 9:04 AM