ATS Pyro-Clean - Cycle Times for Cleaning; Cool-Down before Removing the Glasswear or Metal Parts

28 MAN - Pyrolytic Oven - REV: Original | F. Operation
back of the oven to prevent any organic material from dripping on the oven door gaskets.
F.4 Cycle Times for Cleaning
The Pyrolytic Oven is equipped with an Automatic Cycle Time Feature which adjusts itself to the load placed in
the oven. The cleaning time is limited by the processing speed of the oxidizer. The more asphalt or other organic
residues on the parts, the more smoke that will be evolved o󰀨 the parts during the thermal cleaning process.
The oxidizer is equipped with a temperature sensor and controller which monitors the amount of smoke evolved
o󰀨 the parts and controls the heat-up rate of the oven to prevent the oxidizer from being overwhelmed by too much
smoke. The oxidizer control system will cut o󰀨 the oven heaters if too much smoke is being produced. The oven
temperature seeks whatever temperature is necessary to produce the maximum amount of smoke the oxidizer can
process. Thus the oxidizer actually controls the heat-up rate if su󰀩cient plastic residues are on the parts. When
all of the organic residues are pyrolyzed/vaporized o󰀨 of the parts, smoke evolution will fall o󰀨, allowing the oven
temperature to climb to the normal processing temperature of 900°F to nish o󰀨 the cleaning process.
A cycle time is set on the Setting screen. The Factory setting of 1 hour (3-4 for asphalts) is recommended for most
applications. The Cycle Time does not start until the oven temperature reaches within -10°F of the set-point of the
Oven Temperature Controller. With a normal set-point of 950°F, the Cycle Time does not start timing until the oven
temperature reaches 940°F.
The Cycle Time does not actually start until the oven temperature is within minus 10°F of set-point. This ensures
that the dialed amount of time is a true “time at temperature”. For safety reasons, never set the Cycle Time at less
than 1 hour. This ensures that volatile, pyrolysis gases are exhausted from the oven before the oven shuts down.
For most organics, pyrolysis and vaporization into smoke will actually begin below 900°F, so it is quite common for
the oven temperature to seek a level of about 700 to 800°F while the maximum amount of smoke is being vaporized
o󰀨 of the parts. After the bulk of the smoke is gone, the Oxidizer controller senses this and allows the oven to heat
up to process set-point, typically 950°F. For large glassware, the parts themselves may serve as heat-sinks and
allow the oven temperature to reach set-point even though the parts are too cool to produce enough smoke to turn
o󰀨 the oven heaters. In this case, the oven temp may reach set-point for 20-30 minutes until the glass parts get hot
enough to start signicant smoke production. Then the Oxidizer Controller will take control of the cleaning process
and limit the oven temperature to that which produces the maximum smoke, processing rate of the Oxidizer. Thus
the oven temperature may reach set-point until enough smoke is produced to drive the oven temperature to a lower
level. After all the smoke is vaporized away, the oven temperature is then allowed to climb to 950°F and nish the
cleaning cycle.
F.5 Cool-Down Before Removing the Glasswear or Metal Parts
When the cycle ends, the oven and afterburner heaters shut o󰀨, ending the cleaning cycle. The oven exhaust fan
continues to run to help remove the heat as the oven and afterburner cools. The oven will need to cool to at least
500°F before the door is unlocked and can be opened. Where possible, it is best to let the oven cool down low
enough that the parts can be removed and handled comfortably without special gloves or precautions.