Beckman J2-21M - Page 5

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BECKMAN
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Introduction
The Model J2-21M is a floor-model, refrigerated centrifuge for general
purpose laboratory use. The Model J2-21M is microprocessor-controlled
and introduces a brushless, induction motor. The instrument features:
digital displays, touch switches, keyboard, 10 acceleration rates, 10 decel-
eration rates, 10 program memories, automatic temperature control, and
automatic maximum speed limits.
Digital displays indicate actual rotor speed, rotor temperature, run time
remaining or elapsed, program number, acceleration rate, and deceleration
rate. The displays also show keyboard entries.
Touch switches operate with light finger pressure. These are pressure
switches, not capacitance or thermal switches. There is an audible tone
“beep” when a switch is pressed and activated.
The Model J2-21M operates in the NORMAL, PROGRAM LOCK, and ZONAL
modes. In NORMAL operation, use the keyboard and the parameter entry
keys to select the run conditions, or press only QS, , the appropriate
keyboard digit, and start. . The PROGRAM LOCK mode is for repeating
the same program only. The operator presses only ENTER/RECALL and
START. . The ZONAL mode is used for open-door operation of zonal rotors.
For sample and rotor protection, a rotor will automatically decelerate if
certain abnormal conditions occur. À diagnostic message will flash on the
control panel to signal the condition. Usually the operator can then correct
the condition and restart the run.