Planer Integra 750Plus, Instructions For Use Manual

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12
Introduction to the Integra 750Plus
Heated seals - To prevent icing, heated seals are provided between the chamber door
and body of the freezer.
Freezer furniture - A wide range of specimens can be frozen using a variety of
freezer furniture, including ampoule baskets and racks for straws or blood bags. The
freezer can hold up to four ampoule baskets, and each basket can hold up to 196
ampoules.
Internal programmable controller - The freezer's operation is controlled by an
internal microprocessor-based controller. The controller stores the program that
specifies start temperature, freezing rates, etc. in non-volatile memory. The program can
be retained in memory for several years, even if the freezer's power is disconnected.
You can load a new program by using the DeltaT software on a PC.
Stand-alone operation - The freezer can store a program from a PC and can run that
program independently of the PC.
Cool/heat switches - Push-button switches on the rear panel allow manual control of
the cooling and heating functions.
Safety features - The lid activates an interlock switch to switch off the heater, fan and
liquid-nitrogen solenoid valve when it is opened. Safety from overheating due to sensor
failure is provided by a thermal cutout. A relief valve set to 50psi (3.4bar) is fitted
on the input side of the solenoid valve.
1.6.2
Liquid nitrogen delivery system
It is normal to use a 22psi Dura-Lo or Dura-Tech cylinder to provide the supply of liquid
nitrogen to the freezer. The cylinder is filled by the supplier and, being self-pressurising,
does not require a pump to deliver the liquid nitrogen to the freezer.
Alternatively, a Planer 5psi dewar and pump can be used. The dewar contains the store
of liquid nitrogen, and the pump is inserted into the neck of the dewar. The pump
operates by energising a heater element immersed in the liquid nitrogen; this produces
gaseous nitrogen, which pressurises the dewar and forces liquid nitrogen along a
delivery tube to the freezer. The dewar needs to be filled manually.
It is preferable to use a 22psi cylinder rather than a 5 psi dewar, since it is physically
larger and therefore requires less-frequent filling. In addition, using a 5 psi dewar, the full
specified performance of the system may not be achieved and the rate of cooling during
a seeding pulse is reduced.
The principal components of the dewar and pump are shown in the following diagram.