Vacuum system, operation evaluation

The operation of packed towers under -vacuum conditions is not well defined in the literature. However, the work of Hands and Whitt [33] specifically evaluates several systems operating from 20 to 760 mm Hg abs. Their recommended limiting -vapor velocity is... 

Performance capabilities and capacities can be evaluated using a separate test for each function of the lyophilizer. These tests focus on the operation of selected subsystems and the capacity for the specific functions during lyophilization. These subsystems include the heat transfer system, condenser, and vacuum system. An overview for testing of each major subsystem is presented in the following sections. Also included are examples and illustrations for performance ranges. These examples, however, do not, reflect the capabilities of a specific lyophilizer, nor are they intended to suggest any industry standard. 

The zero creep/laser interferometer system was evaluated using A1 foils [0.002 cm thick, 1.905 cm long]. No thickness tolerance was furnished by the manufacturer, however, no discernible variations were observed using a micrometer accurate to 0.1 /im. The foils were washed in acetone and isopropyl alcohol before being mounted in the reactor. The reactor was evacuated before the sample was heated to temperature. The operating vacuum was 7 10 atm at temperature. Typical runs were from 3-4 days in length, and data was collected every 5 seconds. 

From the numerous and partly new functional principles as discussed in previous sections the number and complexity of the peripheral components needed to operate the PIMMS can be estimated. Besides the PIMMS-chip itself and the environment providing an appropriate vacuum the electronic hardware is another very important parameter, which determines the cost and size of the device. As the many subsystems of the spectrometer and their interactions are not standard, in many respects completely new electronic has to be generated to drive the system and read and evaluate the measurements, respectively. To allow real-time applications, such as online control, several hardware components have to work independently from a central controller, which is another challenge for the firmware and software implementation. This section presents an overview on present state of the hardware, firmware, and software infrastructure for the PIMMS and will outline the further steps for industrialization. 

Reactive-ion etch resistance was evaluated using a Cook Vacuum Products RIE system. Model C71-3 operating at 13.56 MHz. The etch resistance was determined for a two-layer configuration in which the resist was spun on 1.5 m of a polyester planarizing layer (PC-1) supplied by Futurrex Inc. The latter etches approx. 30-50% faster than HPR-204 ( 1500 A/min compared to 1000 A/min for HPR). The etching conditions were Power 0.16 W/cm Bias —350 V Pressure, 20 mTorr O2 Flow rate 15 seem O2. 

The apparatus described herein has been installed and operated in perhaps the most familiar basic glovebox, the Vacuum/Atmospheres Co. (VAC) Model HE-43-2.(2) However, it should be no less feasible to assemble the same or similar equipment into any other rigid wall inert atmosphere enclosure. Most of the systems described here contain components which are available from a number of manufacturers and distributors. In the interest of clarity, and to provide ready access to additional information, a supplier is occasionally identified. Such information does not necessarily imply a recommendation, and the interested reader is encouraged to consider alternate sources and make current cost comparisons. Finally, there is no intent to suggest that the use of these systems is any more or less safe than conventional procedures outside of a glovebox, and as always the chemist must evaluate each alternative (when planning a specific reaction or procedure) on a case by case basis. 

Are there changes in the product (film) that might be due to changes in the vacuum environment The operator s evaluation of film color, reflectance, and uniformity over the fixture can be noted on the process traveler s first check (Sec. 11.4.2). A log of work (work log) performed on the processing system, such as maintenance, cleaning, modification, replacement, etc., including the date and personnel involved, should be kept. These records should be reviewed frequently and discussed with the maintenance/operator persoimel. 

---