22 Collection of liquid nitrogen from chemistry bulk tank storage vessel
Liquid nitrogen
22:1 Notes
22:1:2 If you are new to the Department the following procedures MUST BE demonstrated to you by a competent person.
22:1:3 It is unwise to wheel vessels between the Adrian building and the Chemistry building alone.
22:1:4 Dewars being filled MUST NEVER be left unattended.
22:1:5 Do not twist the fill hose when frozen as this will severely damage it. A replacement will cost over £200. Be patient and allow the pipe to defrost.
22:2 Equipment Required
22:2:1 Safety goggles or preferably a safety visor.
22:2:2 Gloves suitable for use with cryogenic liquids.
22:2:3 Adjustable spanner (for closed Dewars only).
22:2:4 Pen to fill in the log book.
22:2:5 Entrance gate key.
22:3 Filling Open Necked Dewars
22:3:1 Put on goggles and gloves. These MUST BE worn throughout the filling procedure.
22:3:2 Ensure that the phase separator (spray unit) is attached to the flexible fill pipe.
22:3:3 Place fill pipe into Dewar.
22:3:4 Open the outlet valve on the storage vessel (labelled valve no.10) until the Dewar is full.
22:3:5 Turn off the outlet valve (valve no.10) and vent the fill hose by opening the pressure relief valve (small valve labelled P.R.V.).
22:3:6 Remove the fill pipe from the Dewar, leave hose tidy and close the pressure relief valve.
22:3:7 Fill in the log book and lock the gate.
22:4 Filling Closed Dewars
22:4:1 Remove the spray separation unit (spray unit) from the end of the fill pipe.
22:4:2 Connect the fill pipe to your Dewar.
22:4:3 Open the fill and vent valves on your Dewar.
22:4:4 Open the outlet valve (valve no.10) on the storage vessel until your Dewar is full (liquid will flow from the vent valve).
NEVER POINT VENT VALVE ON YOUR DEWAR TOWARDS PEOPLE OR PATHS.
22:4:5 When full close both valves on your Dewar.
22:4:6 Close the outlet valve (valve no.10) on the storage vessel.
22:4:7 At this point your vessel can be slightly pressurised. This will aid liquid nitrogen removal from the closed Dewar.
22:4:8 Open the fill valve on your Dewar then the outlet valve (valve no.10) on the storage vessel for a few seconds. REPEAT AS NECESSARY - THIS WILL BE DEMONSTRATED.
22:4:9 Close the fill valve on your Dewar and close the outlet valve (valve no.10) on the storage vessel.
22:4:10 Vent the fill pipe by opening the pressure relief valve (labelled P.R.V.).
22:4:11 Disconnect the fill pipe from your Dewar (this may be difficult if the connection is frozen - allow to defrost) and replace the phase separator.
22:4:12 Leave the fill hose tidy and close pressure relief valve (P.R.V.).
22:4:13 Fill in log book and lock gate.
22:5 In Emergency Contact
Jim Mackley Biochemistry (phone 3444)
Keith Wilkinson Chemistry (phone 2114)
OUT OF HOURS EMERGENCY TELEPHONE NUMBER:
0191 4164104 (Statebourne Cryogenic Ltd) AND IS PRINTED ON THE STORAGE VESSEL.
