Procedure for Preventive Maintenance of Level Transmitter (Type: GWR)

Procedure for Preventive Maintenance of Level Transmitter (Type: GWR)

GWR: Guided Wave Radar

SCOPE

The procedure encompasses necessary steps to conduct preventive maintenance of guided wave radar type level transmitter installed on a bridle in a vessel/column in any process/fertilizer or petrochemical industry. 

PROCEDURE:

Firstly, identify the level transmitter that you are planning to perform the preventive maintenance. The purpose is to have clarity for obtaining the permit to work accordingly. IF the level transmitter is associated with DCS then it is highly likely that it would be hooked up with any control loop; take the board room operator to take the control loop on MANUAL mode. If it is integrated into SIS or ESD system, it should be BYPASSED to avoid any inadvertent triggering of logic during the preventive maintenance steps. Obtain safety defeat permission from the respective authority as per your company’s procedure.

 1.    Inspect the cable gland and wiring connection of the transmitter for any damage.

2.    Make sure all electrical connections are tightened properly.

3.    Check the housing seal for any breakage.

4.    Isolate the bridle by closing its valves.

5.    Open the drain valve and completely flush the bridle.

6.    Connect HART communicator with the transmitter.

7.    Observe the reading on the local display and check 4 mA output.

8.    Check the zero calibration of the transmitter. If adjustment is required, apply ZERO trim command.

9.    Close the drain valve, fill the bridle up to 50% of its range, and observe the level through level gauge glass.

10. Observe the reading on the local display and check 12 mA output.

11. Verify 50% value on the local display.

12. Fill the bridle completely up to 100% of its range and observe the level through level gauge glass.

13. Observe the reading on the local display and check 20 mA output.

14. Verify 100% value on the local display.

15. Now take the bridle into service. Open low pressure side valve first and THEN the high-pressure side.

16. Disconnect HART communicator from the transmitter.

17. Remove BYPASS mode from the HMI.