Automatic LN2 Fill Station Instructions Roger Robbins 6/7/2010 Introduction: This is a step by step pictorial instruction document on how to fill a portable Liquid Nitrogen (LN2) Dewar from the Automatic LN2 Fill Station on the back dock of the NSERL Building at UTD. Before you can obtain authorization for this operation, you must be trained by the Clean Room Staff. You must have a knowledgeable buddy with you during the filling operations. No one can ride the elevator with an LN2 Dewar whether it is empty or full. Keys will be issued to authorized and trained representatives of various research groups. Key holders must be the person filling the Dewar if keys are passed to unauthorized users for Dewar filling, disciplinary action will be taken. Be aware that Nitrogen gas does not support life if the Oxygen level in a confined space drops below 19% (normal level is 21%) the space is considered a hazardous space. Also note that N2 asphyxiation may have no symptoms before unconsciousness occurs. THIS IS A HAZARDOUS OPERATION. Instructions: Step 1: Obtain a Buddy to work with you during the LN2 fill operation. (Cleanroom Staff is exempt from the Buddy system) Step 2: If you originate from an upper floor, load the Dewar to be filled onto the elevator and hang the Do Not Enter Liquid Nitrogen Dewar on Elevator sign across the door. Push the Floor 1 button and step out of the elevator. Have your buddy on the first floor to receive the Dewar. 1
Step 3: Roll the portable Dewar to the back dock and set it upright on the floor next to the fill station. Step 4: Fill out the Logbook (Mandatory). Print so we can read it. Step 5: Connect the fill line to the fill tap on the portable Dewar. Step 6: Connect the vent line to the vent tap on the portable Dewar. Step 7: Open both the fill valve and the Vent valve on the portable Dewar 2
Step 8: Unlock the power switch and the LN2 input valve. Step 9: Make sure that the automatic back dock external door is not obstructed Step 10: Turn on the LN2 Fill station the red power on LED will light and the back dock automatic door will open. Step 11: Put on the cryogenic gloves and face mask. Step 12: Open the LN2 Source valve and make sure that the Fill Line Vent Valve is closed. 3
Step 13: Push the FILL button on the front of the fill station console the amber FILLING LED will light and LN2 will flow into the portable Dewar. Note that the portable Dewar pop-off valve will probably spew cold N2 gas. Also note that under some circumstances (empty & warm portable LN2 tank) you may need to hold the FILL button down for just over 3 seconds before the station will start filling. Step 14: When the portable Dewar is full, the fill station will detect a small amount of liquid Nitrogen in the vent line and shut off the fill valve. The green FULL LED will light at this time. NOTE: If the portable LN2 tank is venting through the pop-off valve, the sound will not change when the FULL LED comes on. Step 15: Immediately close the LN2 Source Valve. Step 16: Close both the fill valve and the vent valve on the portable Dewar. 4
Step 17: Immediately open the Fill Line vent valve at the LN2 Fill Station. Step 18: Remove the Vent line from the portable Dewar make sure you are wearing the face mask and cryogenic gloves. Re-hang the line on its hanger. Step 19: Remove the Fill line from the portable Dewar make sure you are still wearing the facemask and cryogenic gloves. Re-hang the line on its hanger. 5
Step 20: Turn off the Fill station power and replace the locks on both the power and LN2 Source valve. The back dock door will automatically close. Step 21: Close the Fill Line Vent Valve at this point. Step 22: Load the Dewar onto a proper transport dolly. Step 23: If your portable Dewar lives on the upper floors, roll the Dewar onto the Freight Elevator and hang the Do Not Enter Liquid Nitrogen Dewar on Elevator sign across the elevator door. Send your Buddy to the home floor to await the arrival of the Dewar. Push the go-to-floor-number button on the elevator control panel and step out of the elevator. Climb the stairs or ride the personnel elevator in the front of the building to your floor and remove the sign and take your Dewar to its home. DO NOT RIDE THE ELEVATOR WITH THE LN2. 6