16
51-650 Model 961/962 Echotel SIL Safety Manual -– Loop Version
Step
Proof Test – Echotel Model 962 Loop (continued)
4
Move the process level to achieve three possible states: 1. both GAPs DRY, 2. one GAP DRY & one
GAP WET, 3. Both GAPs WET. This test confirms operation with all GAP states.
Confirm proper operation of the unit: WET/DRY GAP conditions; 8mA LED, 12mA or 16mA LED is
lighted; Loop current = 8mA ±1mA, 12mA ±1mA or 16mA ±1mA.
a.) Move the process level to achieve state 1. Both GAPS DRY. Confirm proper operation of the
unit: WET/DRY GAP conditions; 8mA LED or 16mA LED is lighted; Loop current = 8mA ±1mA
or 16mA ±1 mA.
b.) Move the process level to achieve state 2. one GAP DRY and one GAP WET. Confirm proper
operation of the unit: WET/DRY GAP conditions; 12mA LED is lighted; Loop current = 12mA
±1mA.
c.) Move the process level to achieve state 3. Both GAPS WET. Confirm proper operation of the
unit: WET/DRY GAP conditions; 8mA LED or 16mA LED is lighted; Loop current = 8mA ±1mA
or 16mA ±1 mA.
d.) If unit fails the tests of steps 4a 4b or 4c proceed to step 5.
e.) Adjust the Time Delay Pot to the original setting. Use HI/LOW DIP switch (as described in
step 2e) to confirm that delay is returned to original setting.
f.) Proceed to step 6.
5
If the unit under test fails to respond to process level changes remove the unit from the process and
bench test.
a.) If the unit under test fails to respond to process level changes remove the unit from the process
and bench test.
b.) Clean the ultrasonic transducer, especially in the area of the sensor GAPs.
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 conditions; 8mA LED, 12mA LED or 16mA LED is lighted;
Loop current = 8mA ±1mA, 12ma ±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.
