5-2
Isotemp Economy Water Bath
Fisher Scientific
Section 5
Operation
Proper setting of the Limit Control is important.
The Limit Control must
be set far enough above the control temperature such that it does not
operate unless the Temperature Control malfunctions. Wide temperature
swings are an indication that the two controls are set too close.
There are two methods that can be used to set the Limit Control. Follow
the steps in
either
Procedure 1 or Procedure 2 to set the bath’s Limit
Control.
1. After the bath has stabilized at the desired set point temperature, note
the cycling of the heater as indicated by the green lamp.
2. Note the length of time that the green lamp is lit. Depending upon set
point and ambient temperature, the lamp will cycle on for a few
seconds and then off for a period of time.
3. While the green lamp is lit, rotate the Limit Control knob counter-
clockwise until the amber lamp illuminates (the green lamp will turn
off), then quickly clockwise again until the amber lamp turns off (the
green lamp will come back on).
4. Observe a few cycles of the green lamp. If the yellow lamp illuminates,
turn the Limit Control knob clockwise until the unit cycles without
the yellow lamp lighting.
1. Using the Temperature Control setting instructions above, set the
water bath 1 to 5° above desired control temperature.
2. Wait until the bath temperature stabilizes.
3. Turn the Limit Control knob counterclockwise and listen for the click
of the control. Turn the knob clockwise and slowly listen for the click.
Repeat this step as necessary each adjustment being less than the last
one.
4. Once a narrow band is established in Step 3, turn the Temperature
Control up to call for a higher temperature (heater on, green lamp on).
The amber lamp will turn on when the limit open turning off the
heater.
5. Without adjusting the Limit Control, set the Temperature Control to
the desired temperature below the limit control.
Setting the Limit
Control
Procedure 1
(Use either Procedure 1 or 2)
Procedure 2
(Use either Procedure 2 or 1)