The official opening in September of the new Darwin Centre in the Natural History Museum by the formidable combination of HRH Prince William and Sir David Attenborough was a great occasion. The building itself, incorporating the extraordinary 65 metre long by 30 metre high concrete Cocoon, is itself impressive but less so than the knowledge that it contains over 20 million plant and three million insect specimens, taking up a staggering three kilometres of cabinet space! There is even room left over for around 300 scientific staff.
It was decided that during the move the plant specimens, around five millions of them in 40,000 shelf loads, should be deep frozen to kill off any lurking insect or microbial infections. Nexus Property Solutions carried out this mammoth task, using three, forty foot long refrigerated containers placed in one of the Museum car parks. Clearly very precise monitoring of the freezing process was required to prevent damage to the plants and for this Nexus called on BSRIA Instrument Solutions, experts in the hire or supply of testing equipment of all kinds. Instrument Solutions deemed that the Grant Squirrel 2040 Data Logger with low temperature Type T thermocouples would be ideal for the task. The Squirrel runs off its internal batteries, saving the difficulty of mains connection to the car park and constant monitoring is simple using a lap-top PC linked to Grant's proprietary Squirrelview Plus software. The machine was particularly suitable as it is easily programmed to accomplish unusual 'one-off' tasks such as this one for the NHM and very simple to use.
The temperature in the refrigerator containers was gradually reduced to -35 degrees, a process taking 30 hours, and the specimens then remained at this temperature for three days. It was essential that defrosting should be extremely gentle to prevent any possibility of condensation in the plant matter, so temperature increases in 10 degrees steps over a period of two days were necessary to recover to the temperature of 20 degrees at which they will be stored in the Darwin Centre.
The whole process was carried out faultlessly and the Nexus employees involved found the Grant Squirrel equipment provided by Instrument Solutions both precise and user friendly. The Darwin Centre itself is proving hugely popular with the general public..
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