Bio-Rad CHEF-DR II System - Manual (Page 8)

and high voltage to the electrophoresis cell is disrupted. The lid also contains a mount at the
upper right for an external temperature probe, which monitors buffer temperature in the cham-
ber, and regulates cooling by the optional Model 1000 Mini Chiller.
Pump and Accessories
The CHEF-DR II system includes a variable speed pump, which provides a suitable flow
rate of buffer through the chamber. Substitution of other pumps could pose a safety hazard and
cause improper flow, and therefore lower resolution. The pump’s power supply is electrical-
ly isolated within the drive module for safety. Its voltage requirement is independent of the line
voltage supplied to the drive module (e.g. 120, 100, 220, or 240 volts). This pump should not
be plugged into any equipment other than the CHEF-DR II drive module.
The pump is connected to Tygon or plastic tubing. This tubing circulates buffer in and out
of the chamber. The tubing may also pass through a water chiller. In this case, the pump
should be located after the chiller, so that buffer flows through the chiller and then to the
pump. Typically, the dial is set at 70, for about 0.75 l/min.
The complete CHEF-DR II system is shown in Figure 1.2.
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Fig. 1.2. The complete CHEF-DR II system, with electrophoresis cell, control module, drive module,
variable speed pump, and optional Model 1000 Mini Chiller.