OXFORD CRYOSTREAM COOLER 700 SERIES

Oxford Cryosystems has re-designed the Oxford Cryostream Cooler to produce an even more reliable, easy to use, versatile and robust system than before. The new 700 Series Cryostream Cooler has been designed to meet the increased demands of both home lab and synchrotron cryocrystallography.

700 series cryostream cooler for x-ray Diffractometry applications. Nitrogen gas cryostream cooler has been specially designed to meet the increasing demands of x-ray crystallographers. Oxford has supplied over 700 systems throughout the world in the past 15 years.

The liquid Nitrogen is drowning up from an unpressurised Dewar vessel by the action of a simple diaphragm pump. The liquid passes through a flexible vacuum insulated transfer line into the cold head. The liquid is evaporated and this vapour then flows along one path of the heat exchanger through the cryostream cooler temperature controller and diaphragm pump. The flow rate of the gas from the pump is then regulated by a variable flow valve in the controller. The gas flows back into cold head where it is re-cooled along the second path of the heat exchanger.

After returning to the cold end of the heat exchanger, the gas temperature is controlled by a heater before the gas enters the cryostream nozzle. The gas then passes down the newly designed nozzle to the sample. The temperature at the cryostat will be the same as the temperature indicated on the controller.

700 series cryostream cooler is supplied with transfer line and temperature controller

700 series cryostream cooler specification

Properties	Performance
Temperature Range	80 - 400K
Liquid Nitrogen Consumption	0.6 litres/hour at 5 litres/minute 1.2 litres/hour at 10 litres/minute
Temperature Stability	Short term: 0.1K Long term: 0.1K
Flow Rate	5 litres / minute and Turbo flow of 10 litres / minute
Coldhead Weight	3kg
Length of Transfer Line	2350mm
Controller Weight	7.1kg
Controller Size	135mm x 244mm x 287mm
Mains Power Supply	230Vac 50Hz or 100/115Vac 50/60Hz
Power Consumption	500VA (with AD41 2000 VA)

New Feature	Details
Coldhead and Transfer Line
Transfer Line	The Transfer Line from the Dewar to the Cryostream Coldhead is about 30 cm longer. This is split between the flexible line (now 1500mm) and the rigid Dewar section (now 900mm). This means the Cryostream can now be run with a greater variety of Deware vessels.
More Options in Set up	The Transfer Line is longer and exits the Cryostream Coldhead at 90°. This reduces the need for the Dewar to be raised off the ground. This is ideal for more awkward, non-standard laboratory set-ups or where the x-ray beam is quite high.
Longer Running Time	The FLOW tube of the heat exchanger in the Cryostream Coldhead is now twice the cross sectional area. This will increase continuous run time by more than four times.
Improved Vacuum Lifetime	The Pumpout Port has been relocated near to the Coldhead to reduce the likelihood of damaging the vacuum insulation when refilling.
New Gas Heater System	The heater and sensor probe has been removed from the nozzle of the Cryostream to improve the robustness of the nozzle and Coldhead. The gas temperature at the crystal position is now controlled in a unique way. The gas temperature is controlled in the Coldhead and the temperature is ‘mapped’ to the crystal position. This means we are showing the temperature at the crystal rather than the temperature somewhere close to the crystal position. Because we map the crystal temperature taking into consideration the temperature changes due to flow rate, there is no need to worry about an 'off-set' of temperature at the crystal. So, what you see on the Controller is the temperature at the crystal and there is no need to add some difference to the value on the Controller as is the case with many systems. What you see is what you get!
Improved Laminar Flow System	With the heater and sensor removed from the nozzle, the laminar flow system is improved. This reduces the possibility of icing and improves the cooling ability of the stream.
More Versatile Coldhead Orientation	The new robust nozzle lends itself to being orientated at any angle. This is highly desirable for setups such as the inverted phi axis where it is necessary to also invert the nozzle.
700 Series Temperature Controller
Smaller and Lighter	The 700 Series Controller has an all-new enclosure with a small footprint. (LxWxHmm) 287 x 244 x 135
Microprocessor	The Controller is fitted with a Hitachi microprocessor with software written in C++ with 64K ZIF socketed EPROM for easy upgrade of software.
User Friendly Front Panel	The Controller interface has been improved making it faster and more simple to operate. Easy to read back lit LCD panels create a larger viewing angle. ‘Digi-Pot’ technology allows rapid input of phase information and scrolling of the information displayed on the LCD panels. Audio output makes for positive feedback from the Controller's keys and other controls.
New ‘Fast Start’	The ‘Fast Start’ facility means the Cryostream Cooler can be started by just switching on and pressing START. This means it is quicker to reach a required temperature without the need to enter complicated programming steps. Programmability is still retained when needed.
New COOL function gives faster cool down	This new function draws liquid from the Dewar at a higher flow rate to cool the Coldhead quickly. This is very useful where time is important, eg. Beam lines. The Cryostream can reach 100K in 20 minutes from warm, an improvement of more than 20 minutes.
Electronic Flow Controller	This unit measures and controls true mass flow and automatically compensates for back pressure in the system.
Variable Flow	The Controller now has variable electronic flow of 5 and 10 litres / minute. This is controlled with the use of a TURBO button on the controller and is useful when higher flows are needed.
Digital Real-Time Flow and Pressure Display	The Controller is now fitted with a digital real-time display of mass flow and back pressure.
Increase Operating Temperature	The operating temperature has been increased by 25K to give a range of 80K to 400K.
Improved Computer Interface	Improved computer interface providing more information and control through the serial port. Microsoft Windows Remote Panel offers improved remote operation and data logging.
‘K / °C / °F’ button for changing units	The indicated units used by the Controller can now by changed from Kelvin to Centigrade or Fahrenheit at any time during operation. This not only change the gas temperature readout, but also all the temperature values.
Program Storage	The E2PROM allows customised phases to be stored and retrieved so complex programs can be saved for future use.
New Heater Controls	The Controller is now fitted with Pulse Width Modulated control of heaters. This is over 90% more efficient so less heat is generated in the Controller. Three heaters and sensors allow for the compensation of any small thermal imbalances.
Improved System Management	The Controller now benefits from advanced System Management. By automatically logging the run-time, the Controller can now display system maintenance requirements.
Better System Protection	'Brown-out' detection - Controller is able to detect power losses enabling continuous running through mains power fluctuations and allows for controlled shutdowns.
Other System Improvements
New Teflon tubing improving the dryness of the nitrogen gas	This tubing is 70 times less water absorbent than the current tubing. This increases the continuous run-time of the system.
New Coldhead Support Stand with Multi-Axis Positioner	The Varibeam Coldhead Support Stand has been modified to include two additional axes of translation as well as the existing translation. These new translations can be fitted to existing Varibeams.
Optional Auto-Refill System	The 700 Series is now available with an optional Liquid Level Controller. This unit comes with a customised Dewar Cap Assembly for the ES-60 Dewar, discrete sensors to control the level of liquid in the Dewar, transfer line and solenoid valve.
New Diaphragm Pump	In order to improve the reliability and lifetime of the pump parts, the system will by shipped with the newer 917 Diaphragm pump.

         

 
AD41 Dry Air Unit

When using any low temperature device, it is very important to shroud the cryogenic nitrogen gas stream in a second gas stream to prevent atmospheric moisture from freezing and causing icing of the crystal. The combination of this outer and inner stream is called the Laminar Flow System. When the flows are balanced and free from turbulence, the outer stream protects the inner nitrogen stream.

Oxford Cryosystems has found that the best and most cost-effective way to produce a laminar outer gas stream for the Cryostream, is to use dry air from the AD41 Dry Air Unit which contains a compressor producing air that is dried by two drying columns.

This system means that you use much less liquid nitrogen, (sometimes less than half,) compared with other low temperature systems which derive their outer stream from the liquid nitrogen supply. Secondly, an outer stream with a variable and pressurised flow gives the flexibility of protecting the stream from turbulence by adjusting the flow rate, something that is impossible to do with unpressurised or heated outer gas streams.

Specification

This new AD41 Dry Air Unit has incorporated over one million hours of service and experience from the AD31. Its features include:

      ·        Variable flow up to 25 litres / minute
·        Dry air with a dew point of -60ºC
·        New microprocessor functionality to give long term cycle 
          accuracy and reliability
·        Improved sound proofing and reduced resonance for quieter 
          running
·        Increased service intervals with quicker and easier user 
          maintenance
·        New AD41 Remote Panel to control the unit up to 30 
          metres away
·        Improved air flow and cooling to increase component 
          lifetime  

Properties	Performance
Size	660mm x 300mm x 415mm
Weight	42kg
Mains Power Supply	230Vac 50Hz or 100/115Vac 60/60Hz
Power Consumption	2000VA

 For more details please contact: hpi@bgl.vsnl.net.in or visit: www.OxfordCryosystems.co.uk