KROHNE DK 32-DK 34-DK 37 Safety V1 EN - Manual (Page 10)

6
LIFE TIME / PROOF TESTS
10
DK32 - DK34 - DK37
www.krohne.com 02/2012 - 4000574702 MA DK32 34 37 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 DK32, DK34, DK37M8M 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 DK3* 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 DK3* 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
Proof test for DK37M8E 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 are flowmeter DK37M8E
3. Force the variable are flowmeter DK37M8E to go to the high alarm current output and verify
that the analog current reaches that value.
4. Force the variable are flowmeter DK37M8E 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.
MA_DK32_34_37_SIL_R02_en_574702_PRT.book Page 10 Thursday, March 1, 2012 9:53 AM