12
51-650 Model 961/962 Echotel SIL Safety Manual -– Loop Version
Step
Proof Test – Echotel Model 961 Loop (continued)
5
If the unit under test fails to respond to process level changes remove the unit from the process and
bench test.
a.) Remove the unit from the process. Inspect the ultrasound transducer for evidence of damage or
coating buildup. Fouling on the transducer surface may interfere with normal operation. If heavy
fouling is evident, it is suggested to service the transducer more frequently.
b.) Clean the ultrasonic transducer, especially in the area of the sensor GAP.
c.) Perform a bench test per the steps of section 4. When possible it is best to use the actual
process material, because materal properties affect the ultrasonic performance. Confirm proper
unit operation: WET/DRY GAP condition; 8mA LED or 16mA LED is lighted; Loop current = 8mA
±1mA or 16mA ±1mA
d.) If unit passes the tests of steps 5c, return to the process installation and repeat the tests of
step 4.
e.) If the unit fails re-test in the process, it must be replaced.
6
Proof test is complete. Restore loop to full operation.
