User`s manual

24 Chapter 4: Hardware Description
Calorimetry Sciences Corp.
CSC 5300 N-ITC III 25
User’s Manual
Extreme care should be taken not to bend the syringe needle
because this would impair proper stirring and possibly damage
the reaction vessel.
Each syringe needle is equipped with
a attened, slightly twisted paddle at
the tip which does the actual stirring of
the solutions in the cell. The stirring
paddle spins clear of the sides of
the reaction vessel. When stirring is
activated the contents of the reaction
vessel are stirred continuously until the
end of the experiment or until stirring
is turned off.
Stirring is controlled by a stepping
motor mounted inside the calorimeter.
This type of motor is used because of
its very constant and adjustable speed.
The motor drives the rotating shaft
of the burette which holds the titrant
syringe, and torque is transmitted to
the stirring paddle through the syringe
needle.
Burette Assembly
The burette functions to accurately deliver the titrant to the reaction vessel at user speci-
ed volumes and intervals. The assembly doubly functions as the stirring mechanism
for the reactants in the cell when the titrant syringe is installed. The rotating shaft on the
lower portion of the burette assembly holds the titration syringe in place, and has two
external O-rings which provide the friction necessary for the stir motor to rotate the shaft
during operation.
When the syringe is lled with titrant, the plunger and barrel are carefully inserted into the
Figure 4-2: The sample cell assembly.