Diff: CryogenicHandling

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JSPWiki v2.0.52


Difference between version 42 and version 8:
At line 4 added 6 lines.
+ Handling cryogenic liquids should only be done by trained people. The following instruction are by no means a replacement for a certified cryogenics course. They are meant as a reference for how to handle cryogenics at the Neutron guide hall. \\
+ Fear is a bad teacher
+ and you should always consult a more experienced instrument scientist or [the sample environment team|SampleEnvironment],
+ if you are in doubt how to handle things correctly. \\
+ Please always keep in mind that you are working with boiling liquids which will evaporate rather quickly when exposed to ambient temperatures.\\
+ Think about the consequences of your doing __before__ you do it (e.g. what will happen if you open a specific valve).
At line 5 added 1 line.
+ For information on how to set up an orange cryostat and how to change samples, please follow this link: [OrangeCryostat|http://lns00.psi.ch/sinqwiki/Wiki.jsp?page=OrangeCryostatCooldownProcedure].
Line 12 was replaced by line 19
- [LN2_dewar_schematics|cl_clpb.gif]
+ [LN2_dewar_schematics|LN2.png]
Lines 16-17 were replaced by lines 23-24
- The filling hoses have a metallic protection sleeve. The valves and the hose get very cold during a nitrogen transfer.
- *Make sure that you wear protective leather gloves when handling cold parts.
+ The filling hoses have a metallic protection sleeve. The valves and the hose get very cold during a nitrogen transfer.
+ *Make sure that you wear protective leather gloves when handling cold parts, however the gloves should never be soaked with LN2 or LHe.
At line 18 added 1 line.
+
Line 24 was replaced by line 32
- Liquid Helium dewars are provided by the sample environment staff at the sample preparation area.\\
+ Liquid Helium dewars are provided by the sample environment staff at the preparation area.\\
Line 28 was replaced by lines 36-37
- *Always measure the Helium level in the dewar before you take a Dewar away
+ *The Level meter in the preparation area shows the level in litres. Make sure that there is sufficient helium for filling. The dewars
+ should be returned with a level of at least 10-15 litres.
At line 30 added 1 line.
+
Line 33 was replaced by lines 43-52
- __Helium Transfer:__\\
+ __Helium Dewar Transport:__\\
+ Helium dewars are brought into the experimental area with the 1T crane.
+ *Only instructed people are allowed to use the crane. (A short training is offered by the LDM mechanics personal.)
+ *Only dewars with pre-installed transport straps are allowed for crane transportation.
+ *To extend the straps please use the proper extensions as shown in the picture below.
+
+ | [transport extensions|HeDewartransport.png] | [dewar with transport fixtures|transportstraps.png]
+
+
+ __Helium Transfer:__
Line 37 was replaced by line 56
- *slowly lower the siphon into the dewar observe the pressure rise in the dewar (try to stay below 0.2bar)
+ *slowly lower the siphon into the dewar and observe the pressure rise in the dewar (try to stay below 0.2bar)
Lines 41-44 were replaced by lines 60-65
- *continue to lower the siphon into the transport dewar until you reach the bottom and lift it up by 10 cm
- *switch on the compressed Helium gas line and connect the gas hose to one of the pressure release valves\\
- and open it. The dewar is now pressurized to 0.2bar over pressure.
- When the transfer is finished:\\
+ *continue to lower the siphon into the transport dewar until you reach the bottom.
+ *switch on the compressed Helium gas line and connect the gas hose to one of the pressure release valves
+ and open it. The dewar is now pressurized to 0.15 bar over pressure.
+ *make sure not to empty the vessel completely, the people running the liquefier will love you. On the transfer line, normally there is a prolongation with a hole at 10 cm above the end. If not, you should lift the transfer line by 10 cm after inserting.
+ When the transfer is finished:
+
Line 47 was replaced by lines 68-69
- *make sure that the extraction and filling ports are properly sealed
+ *make sure that the extraction and filling ports are properly sealed. It might be necessary to
+ use a hair dryer to remove the ice.
Lines 51-58 were replaced by lines 73-84
-
- !Automatic Cryostat Control and Monitoring
-
- All our cryostats are monitored and controlled with [SEA|http://lns00.psi.ch/sinqwiki/Wiki.jsp?page=Sea].
- All instruments are equipped with a temperature controller (Lakeshore 340) for the temperature control and a cryostat control unit (CCU)
- for the control of pressures, levels and valves.
- The CCU will only work with a correctly configured SEA instance. It can read the pressure in the VTI pumping line (see [orange cool down|http://lns00.psi.ch/sinqwiki/Wiki.jsp?page=OrangeCryostatCooldownProcedure] and set the needle valve accordingly. It reads the analog output of AMI Helium level meters and serves as a level indicator for our 2 point
- liquid Nitrogen level meter. The Unit is used to energize the electromagnetic valves involved in the automatic Nitrogen/Helium refill.
+ !Returning Liquid Helium Dewars
+ please return dewars to the dewar station as soon as possible after the transfer
+ *connect the dewar to the rubber hose of the dewar station
+ *open the manual valve to the recovery
+ *open the manual pressure release that is connected to the recovery on the dewar
+ *check the other manual pressure release. it MUST be closed
+ *retighten the locking nut of the Helium extraction port
+ *connect the level probe
+
+ IMPORTANT:
+ recheck that all valves are in the right state and the level is reading before you leave
+ [afterfill.png]
Line 60 was replaced by line 86
- [CCU|CCU.png]
+ In case you are unsure about certain procedures, please contact sample environment staff

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