DETERMINATION OF HEAT PENETRATION PARAMETERSMeans of accurately determining the temperature of the container contents. The initial temperature(s) measured should be considered in the context of retort shell and crate temperatures, which may be lower or higher than the product temperature, and could have an effect on the total heat load required to adequately vent the retort.8.2. data collection points:8.2.1. the following are critical and should be monitored and recorded during the test:8.2.1.1. controller temperature set point.8.2.1.2. initial temperature.8.2.1.3. steam on or “0” time.8.2.1.4. time and temperature when the drain is closed, if it is open during a portion of the vent.8.2.1.5. time and temperature of the retort when the vent closes, taken from the MIG thermometer and reference TMD.8.2.1.6. time when the reference TMD (attached to or in close proximity to the MIG thermometer) reaches the processing temperature set point.8.2.1.7. time when the controller (if appicable) advances to the “cook” cycle in the program.8.2.1.8. MIG thermometer readings – at sufficient intervals, including the time it reaches the processing temperature set point.8.2.2. in adition, the following points are important and are highly recommended to be monitored and recorded dring the test:8.2.2.1. retort steam header pressure and temperature, if superheated steam is a concern, and/or steam pressure at the end of the spreader.8.2.2.2. time when the temperature recording device reaches the processing temperature set point.
8.2.2.3. retort pressure gauge (optional) – readings at sufficient intervals including the time it reaches processing temperature.
8.3. conducting the test:
8.3.1. the data logger should record the temperature of each TMD just prior to “steam on” and at sufficient intervals, not to exceed 1 minute, throughout the test. The data logger record should become part of the critical records for the test.
8.3.2. critical points should be recorded at intervals of sufficient frequency to describe and verify retort operating parameters during the test. These records become part of the test records and should include the temperature recording chart(s).
8.3.3. the test should extend for at least 10 minutes after the retort control system has stabilized and a definite temperature profile has been established or all temperature monitoring devices have reached a steady state condition.
8.3.4. idelly, no TMD shuold read more than plus or minis 1.00F (0.60C) from the reference TMD at the time it first indicates the processing temperature set point has been reached. Situations or conditions that do not meet these criteria should be evaluated by a themal processing specialist.
1. these guidelines have been reproduced by the permission of the institute for thermal processing specialist. Additonal copies and information can be obtained by addressing this institute at P.O. Box 2764, Fairfax , VA 22030 – 0764.
The selection of the test retort from a series of production retorts assumes that they are all of the same type (horizontal or vertical), and that they have the same system for the introduction and distribution of the heating and cooling media and the same medium, spreader, pumps, fans, and so on, should aloso be subject to be separate tests as the temperature distribution may well be different.
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