During preparation for the analysis of elements and isotopes at ultra trace concentrations, samples are subject to contamination caused by impurities from reagents as well as from the components of atmosphere and equipment and instrumentation in the laboratory. The atmosphere in the lab is strongly influenced be the acids used. Acid vapors corrode the surfaces of metals and other materials within the lab, thus starting a contamination avalanche. Superior quality of analysis will require a well tuned system of facilities and equipment for sample acquisition, sample digestion, for purification of acids and for the handling of samples down to instrumental analysis.
With the PicoTrace Clean room concepts and Safety-Clean-Air-Cabinets RLK particles from the lab atmosphere shall be removed and the back flow of acid fumes from the preparation processes to the lab will be avoided. Without these prerequisites many analytical attempts may fail. Clean room conditions for the working space to protect sample digestion, separation techniques, and sample handling will be available at economic costs only, if that volume is reduced. PicoTrace Safety-Clean-Air-Cabinets RLK will provide ultra clean class 100 and better conditions according to US Fed. Standard 209D (1988) within the space of that activities. Depending on the selected cabinet type, the clean air flow will be directed either vertical or horizontal through the working space.
Body and structure of our Clean Air Cabinets RLK are made from acrylic glass (polymethyl metacrylate). Surfaces in the vicinity of hot plates can be made from Poycarbonate, because of better heat resistance. The cylindrical blower/motor assembly, the Time-Temperature-Controllers for the PicoTrace Safety Hot Plates SFH, the security control systems and the whole electrical installation is concentrated in the blower module, prior to the filter in the air stream, thus protecting this components against corrosion. Repairing will not influence the clean air space. The blower, designed for quiet operation, economy and endurance serves a controlled constant air flow even with changing permeability of the filter. A system controlling the pressure difference allows to watch over the pressure relations between the cabinet volume and the lab even while operating with open doors. The motor/blower assembly, filter materials and surface conditions are optimized for long cycle times, to avoid contamination caused by filter exchange or service operations.
The cabinets may be easily connected with clean air and waste air lines. Any back flow of condensed fluids is kept off. To avoid infiltration of lab atmosphere into the clean air space of the cabinet and of acid fumes or dangerous particles out of the cabinet into the lab, gaskets will be used with the sliding doors, and sophisticate air shields. Standard filters at standard dimensions are used for ease of exchange. Life cycles of five years ore more will be attained if the cabinet is supplied with prefiltered air. A special designed PTFE air passage provides the laminar air flow in the working space of the cabinets.
The cabinets are modular designed. They provide up to four working spaces. In the working spaces of the horizontal air flow cabinets, manipulations is executed against the clean air flow, to exclude sample contamination. Up to four PicoTrace Safety Hot Plates SFH 2820 N may be installed in the horizontal air flow cabinets, with their controllers in the blower module, and a maximum of six in the vertical air flow cabinets. The cabinets may also be used with the PicoTrace Pressure Digestion System DAS.
In the cabinets with vertical airflow, a cunning airflow direction and exhaust system is provided, to direct the vertical airflow to a horizontal flow, if this is required by the experimental conditions (i.e. evaporation processes). It is possible to combine different modules with a separating sliding door between the two. This doors close tightly against acid fumes or other volatile components. So samples may be moved from one unit to the other for different processing without leaving the clean air conditions of the cabinet.
All cabinets will be designed on the basis of available modules on users demand. So almost every customers applications will be met. This is especially due to the size of the clean air working space, the clean air and waste air conduction, the outfit with controllers and additional equipment. The attached construction sketches may be used for stimulation only.
Fields of application for PicoTrace Clean - Air - Cabinets
- Evaporation of liquid solutions
- Evaporation of acids
- Ion exchange processes
- Sample transfer to the measuring instrument
- Water analysis
- Filtration and dilution
- Working on clean matrices
- Preparation of samples for mass spectrometer measurements
- Sample digestion
- Storing samples and equipment
- Particles producing preparations
- Cleaning and assembling of high sensitive technical parts
- Working within special gas atmospheres, etc.
PicoTrace safety concept for Clean Air Cabinets RLK
- The field of use is thoroughly discussed with the user.
- All components are adjusted to customers demand and local regulations.
- Internal / external control of
- Temperature in the system.
- In case of serious faults, all heating processes are cut down.
- No automatic power reset after current drop out for sensitive modules.
- Sophisticate designed gaskets for all sliding doors, to exclude interactions with the surrounding atmosphere.
- Special air shields to protect the experimental area but also the operator.
- Incorporation of PicoTrace Safety Hot Plates SFH 2820 or SFH 5030 combined with PicoTrace Time - Temperature - Controllers with the following specifications:
- The temperature controller is separated from the hot plate and positioned outside the aggressive atmosphere in the fan box.
- The hot plate is microprocessor controlled, operates with great precision and is highly resistant against acid attack. The temperature and regulation parameters are continuously displayed.
- The reliable control of the temperature guarantees reproducible conditions for chemical reactions.
- Both, controller and hot plate are supplied with independent temperature limitation switches.
- The controller is twice protected against overriding a set temperature.
- If both safety elements fail, three independent temperature limitation switches of the hot plate react successively. Two of them will be reset, if the temperature of the hot plate has decreased 6 to 10°C. The third system is controlled by an additional independent PT-100 sensor. It has to be reactivated manually.
- All safety functions may be easily checked.
The price for this ultimate technical solutions is high. However, in the face of the potential danger emanating from traditional hot plates, it is economical, especially if one takes into consideration the considerable effort that has been invested in the samples prior to there processing in clean air cabinets, and the costs of cleaning and renovation of a clean lab. This high safety standard is absolutely necessary if the systems will be run continuously without personal control or if dangerous chemicals like hydrofluoric or perchloric acid are involved during the course of sample preparation.
