Bruker BioSpin NMR Fourier 300, Руководство по планировке объекта

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Installation
of the cryostat can begin. At the same time the cryostat is flushed through with dry Nitro-
gen gas. The customer
must provide a 50l/200 bar cylinder of dry Nitrogen gas (99.99%
purity). The cylinder must be fitted with a secondary regulator valve to deliver a pressure
of 0.5 bar. For some installations the customer is asked to provide a roughing pump, e.g.
rotary pump capable of reducing pressures within the cryostat to 10
-2
mbar.
Further pumping of the cryostat is then carried out to reduce the internal pressure to

10
-6
mbar. It is convenient, particularly for foreign installations, if the customer can
provide a suitable pump such as a diffusion or turbo pump. If such a pump is available
the customer must contact Bruker BioSpin to confirm its suitability. Where no such pump
is available, it will be supplied by Bruker BioSpin.
5.2.3 Cooling the Magnet to Liquid Nitrogen Temperatures
This next stage involves filling the magnet with liquid Nitrogen. The quantity of liquid
nitrogen required is
150 Liters . To transfer the nitrogen a transport dewar is required.
This must have a minimum volume of 50 Liters with fixture for pressurizing and
transferring via a rubber hose of 10 mm diameter.
5.2.4 Cooling the Magnet to Liquid Helium Temperatures
• For this procedure the customer must provide:
• One cylinder of helium gas: 50 l / 200 bar (99.996% purity) with secondary regulator
valve to deliver pressure of max 0.2 bar.
• The quantities of liquid helium is 150 l.
• Liquid Helium dewar: 50 l, 100 l or 250 l. Type SHS with NW25 flange or suitable
outlet compatible with the 9.6 mm helium transfer line.
When ordering the helium the customer must arrange to have it delivered immediately
before the installation. Otherwise losses due to evaporation must be taken into account.
5.2.5 Charging the Magnet
The final stage involves bringing the magnet to field. During the charging there is a
possibility that the magnet may quench. A minimum quantities of liquid helium is
required to allow at least for one quench. It is important that the customer ensures that, if
required, extra supplies of liquid helium are available.
Note: Many suppliers will buy back any unused cryogens!