Boekel Scientific 25515016 Cement Autoclave - Manual (Page 8)

heating coils is in use, yet enough power is supplied to raise the pressure of the
apparatus from 160 to 295 PSIG within the allowable heating period.
b) Remove the thermometer and insulated cover. Then gradually tighten the bolts for
the third time as carefully as before. This final adjustment is necessary for the
successful operation of the autoclave, as it tends to prevent leakage of steam
through the gasket and thereby conserves the small quantity of water at the
bottom of the cylinder.
c) Replace the cover and the thermometer.
4.4 Three-hour Constant Temperature & Pressure Period:
During this period, Switch #1 and the Main Switch remain ON and the temperature is
automatically maintained by the sensitive controller which switches the current on and off
(indicated by the pilot light) through the relay. When the system is tight enough so that
no steam or water is lost by leakage (and the draft lever remains in the “closed” position)
the heating current will be on for about 40-50% of the time.
4.5 Cooling Period
At the end of the three-hour constant temperature and pressure period, proceed as
follows:
a) Turn the main switch to the OFF position.
b) Remove the thermometer. Remove the insulated cover and replace the
thermometer.
c) Move the draft lever to the OPEN position on the extreme left.
This increases the amount of cold air, which enters the cylindrical opening at the bottom
of the autoclave and leaves through the annular space at the top of the autoclave. The
circulation of cold air around the walls of cylinder by natural draft greatly facilitates rapid
and uniform cooling.
Under these conditions the gage pressure will decrease to about 10 PSIG within one and
one-half hours. At the end of this period, proceed as follows:
d) Open the vent valve to equalize the pressure in the cylinder with atmospheric
pressure.
e) After the excess pressure has been released, remove the bolts and cylinder head.
f) Remove the gasket from the groove in the cylinder and remove any pieces
adhering to the cylinder head. The gasket is easily removed when it is damp and
warm.
8