Cryogen fills

Gloves and eye protection are stored on the bookcase to the left of the npa600 workstation.

Nitrogen

Before starting

  • The magnets need to be filled when the liquid nitrogen meter reads 6.
  • Filling npa600 from "6" takes about an hour. Filling bma600 from "6" takes about two hours.
  • Fills require low pressure liquid nitrogen (22psi, not 230psi).
  • Filling one magnet will take about half of a 230L tank of liquid nitrogen.
  • Make sure the liquid nitrogen transfer line is connected to the port labeled “liquid”.

Procedure

  1. Move the liquid nitrogen tank to within one meter of the magnet.
  2. Remove the silver one-way valve on the top of the magnet by grabbing the bottom and lifting straight up, then replace it with the short length of rubber tubing.
  3. Ensure the rubber tubing is pointing away from the magnet.
  4. Place the lid on top of the magnet bore.
  5. Open the liquid nitrogen valve on the tank and blow gas through the transfer line to cool it.
  6. When liquid starts to spit from the end of the transfer line close the valve on the tank.
  7. Remove the black heat exchanger on the top of the magnet and replace it with the free end of the nitrogen transfer line.
  8. Open the liquid nitrogen valve on the tank until the transfer line starts to shake a little.
  9. Allow the liquid nitrogen to flow until liquid starts to spit from the rubber tubing.
  10. Close the liquid nitrogen valve on the tank.
  11. Wait 5-10 minutes for the rubber tubing and the transfer line to defrost.
  12. Remove the rubber tubing and replace the silver one-way valve.
  13. Remove the transfer line and replace the black heat sink.
  14. Remove the lid from the top of the magnet bore.

Tips

  • After filling the magnet the rubber tubing will defrost before the transfer line. You can speed up defrosting the rubber tubing a little by carefully holding the end connected to the magnet with your bare hand.
  • Do not try to warm up the metal transfer line with your bare hand. To quickly defrost it you can use the heatgun which is stored on the bookshelf to the left of the npa600 desk.
  • If the liquid nitrogen tank runs empty during a fill you will hear a whistling noise from the transfer line. Close the liquid nitrogen valve. If you have another liquid nitrogen tank available you can remove the transfer line from the empty tank and attach it to the new one. The correct sized wrench is in the top drawer under the npa600 desk.
  • Written by Brendan Duggan. Last modified 2015-Jul-17

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