(5) The heater power switch is used to select the appropriate heater power lev-
els for heating and controlling temperatures.
7.2
Bath Tank and Lid
The bath tank and lid assembly includes: (1) the tank, (2) the control probe, (3)
the stir motor, (4) the access hole, (5) the access hole cover, and (6) the bath
drain. (See Figure 4 on page 24.)
(1) The bath tank is constructed of stainless steel and is very resistant to oxida-
tion in the presence of most chemicals and over a wide range of temperatures.
(2) The control probe provides temperature feedback signal to the controller al-
lowing the controller to maintain a constant temperature. The control probe is a
precision platinum resistance thermometer (PRT). The control probe is delicate
and must be handled carefully. The probe is placed in the small hole in the top
of the bath so that the probe tip is fully immersed in the bath fluid. The probe
cable connects to the bath at the probe connector on the back panel.
(3) The stir motor is mounted on the bath tank lid. It drives the stirring propel-
ler to provide mixing of the bath fluid. Proper mixing of the fluid is important
for good constant temperature stability. The stir motor power cord plugs into
the back of the bath at the power socket labeled “STIRRER”.
(4) On the bath lid is a large rectangular access hole. This hole is used for fill-
ing and emptying the bath with fluids and placement of thermometers and de-
vices into the bath. When possible the access hole should be covered. The
working area
is defined as one inch from the sides and bottom and three
inches from the top of the fluid.
(5) An access hole cover is recommended to cover the large square access
opening in the top of the bath. This improves bath temperature stability, pre-
vents excess fluid evaporation or fumes and increases safety with hot fluid. The
user may drill or cut holes in the cover to accommodate the instruments to be
calibrated or immersed in the bath. Spare covers are available from Hart
Scientific.
(6) A drain valve is provided for ease of removing the fluid media from the
bath. Always use a container of adequate size to hold the
full load
of fluid.
Some oils are more easily drained at higher temperatures. (See caution note
below.)
CAUTION:
Extreme caution must be maintained to prevent harm to the
user or the surrounding environment. Do not exceed a 120°C fluid temper-
ature for draining. The valve could be damaged if 120°C is exceeded. In-
sulate the container from the floor or other objects that may be damaged
by high temperatures as required.
25
7 Parts and Controls
Bath Tank and Lid
