2020 Tech Report Jan-Feb

Task # 2.a.: Cleaning a Strainer in a Configuration “A” Control Group: Drain Valves

ACTION

COMMENT

4.

Slowly close Valve “A.” Apply lock and tag per the facility’s Lockout / Tagout Pro- gram. Change the automatic valve’s manual operating stem to the “MANUAL OPEN” operating position. Valve “B” Solenoid If possible, allow the section of the sys- tem / piping with the control valve to pump down by isolating the liquid feed while maintaining the refrigeration suction. Lower the pressure in the isolated sec- tion of the piping to the lowest pressure available.

5.

6.

NOTE: Any frost on exposed portions of the pipe or valves should disappear with the liquid ammonia in the system. NOTE: If the isolated piping is in a vacuum, take precautions to prevent water from being drawn in when purging the piping. NOTE: If Valve “D” is a hand expansion valve as shown in Figure #2, the number of turns re- quired to close the valve must be recorded in the Master Maintenance Log (or facility equiv- alent). NOTE: Hand expansion valves should never be used as a positive shut-off unless no other option is available, such as in Figure #2. CAUTION: Failure to properly secure the end of the hose in the water bucket can lead to the hose coming free, whipping around, and possibly causing injury to personnel nearby, as well as allowing ammonia vapor to escape to the atmosphere directly. CAUTION: Opening Valve “C” too fast or too far can cause water / ammonia mixture to splatter from bucket.

7.

8.

Slowly close Valve “D.” Apply lock and tag per the facility’s Lockout / Tagout Pro- gram.

9.

Confirm Valve “C” is closed.

10. 11.

Carefully remove the plug from Valve “C.” Attach a suitable hose, approved for am- monia service, to Valve “C.” Terminate and secure the opposite end of the hose (currently attached to Valve “C”) in a bucket of water outside and downwind of the plant if possible.

12.

Slowly throttle open Valve “C.”

RETA TECHNICAL REPORT PAGE 8