Market Forge Industries STM-E, Owner'S Manual, Page: 24 / 36

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SECTION 5 ASSEMBLY
EXPORT
THE PRESSURE ACTUATED TEMPERATURE CONTROL, STM-EX AND STM-ELX
The pressure actuated temperature control, located behind the control panel assembly,
governs the manufacture of steam by controlling the input of electric current to the heating
elements.
HOW IT WORKS
When the timer is set, rear and front contactors will become energized allowing input of
current to the temperature control, thus closing the contacts completing the current to the
heating elements. Steam will then be generated within the sterilizing chamber.
The steam pressure within the sterilizing chamber is transmitted by means of a tube to the
bellows of the temperature control; as the steam pressure increases, its compression action
on the bellows causes the contacts to make or break according to the condition of the
pressure at that time (rising or falling).
Switch #1 on the control is set to cut out on rising pressure at
0.89 kg/cm
2 and to cut in on
falling pressure at
0.84 kg/cm
2
(controlling the two outer banks of heating elements). Switch
#2 is set to cut out on rising pressure at
0.89 kg/cm
2
and cut in on falling pressure at
approximately
1.05 kg/cm
2
(controlling center heater element only) .
Thus, a balancing effect of steam pressure build-up and heater element current is constantly
maintained during the sterilizing cycle. When the Timer signifies the end of the cycle, the
electric current to the contactors will automatically be broken.
CHECKING THE 110°C. SETTING, STM-ELX
The Unit should be completely evacuated then temperature selector dial turned to 121
o
C
Centigrade. Observe the current until it takes a sharp drop to approximately one-third of the
full load; at this instant, there should be a corresponding chamber pressure of
0.14 kg/cm
2
.
Observing the current further will show another sharp drop to approximately 1 Amp; at this
instant, there should be corresponding chamber pressure of
0.43 kg/cm
2
and a temperature
reading of 121°C Centigrade, on the temperature gauge.
ADJUSTING THE RANGE OF OPERATION,
STM-ELX
The range of operation of Model STM-ELX is
adjusted by simply turning the adjusting knob on
the outside of the Control Panel. A counter-
clockwise turn decreases the pressure while a
clockwise turn increases the pressure. Observe
pressure and temperature gauges and adjust
knob as required.
NOTE: When resetting this control for elevations above
sea level, a correction of 0.13 kg/cm
2
per kilometer
elevation is necessary.