Containment devices

Personnel are protected in working with tritium primarily by containment of all active material. Containment devices such as process lines and storage media are normally placed in well-ventilated secondary enclosures (hoods or process rooms). The ventilating air is monitored and released through tall stacks environmental tritium is limited to safe levels by atmospheric dilution of the stack effluent. Tritium can be efficiently removed from air streams by catalytic oxidation followed by water adsorption on a microporous soHd absorbent (80) (see Absorption). 

A regulator is a compact device that maintains the process variable at a specific value in spite of disturbances in load flow. It combines the functions of the measurement sensor, controher, and final control element into one self-contained device. Regulators are available to control pressure, differential pressure, temperature, flow, hquid level, and other basic process variables. They are used to control the differential across a filter press, heat exchanger, or orifice plate. Regulators are used for monitoring pressure variables for redundancy, flow check, and liquid surge relief. 

Where product is exposed at transitions or packing operations use containment devices such as gloveboxes provide airflow control (laminar flow booths) or as a last resort use the room as containment and provide suitable personal protective equipment for the operators... 

Liquids stored under pressure above their normal boiling point temperature present substantial problems because of flashing. If the tank, pipe, or other containment device develops a leak, the liquid will partially flash into vapor, sometimes explosively. 

The key to safe handling of chemicals is a good, properly installed hood, and the referenced book devotes many pages to hoods and ventilation. It recommends that in a laboratory where people spend much of their time working with chemicals there should be a hood for each two people, and each should have at least 2.5 linear feet (0.75 meter) of working space at it. Hoods are more than just devices to keep undesirable vapors from the laboratory atmosphere. When closed they provide a protective barrier between chemists and chemical operations, and they are a good containment device for spills. Portable shields can be a useful supplement to hoods, or can be an alternative for hazards of limited severity, e.g., for small-scale operations with oxidizing or explosive chemicals. 

BSL 2 Biosafety Level 2 is suitable for work involving microorganisms of moderate potential hazard to personnel and the environment. Safety equipment Class I or II biosafety cabinets or other physical containment devices laboratory coats, gloves, face protection as needed. Microorganisms include hepatitis B virus, HIV, salmonellae, and mycoplasma. 

Siloxane-containing devices have also been used as contact lenses, tracheostomy vents, tracheal stents, antireflux cuffs, extracorporeal dialysis, ureteral stents, tibial cups, synovial fluids, toe joints, testes penile prosthesis, gluteal pads, hip implants, pacemakers, intra-aortic balloon pumps, heart valves, eustachian tubes, wrist joints, ear frames, finger joints, and in the construction of brain membranes. Almost all the siloxane polymers are based on various polydimethylsiloxanes. 

Regulatory facts ATSDR - minimal risk level (MRL) - inhalation 0.2 ig/m3 General facts long history of use, liquid silver evaporates at room temperature, bacteria convert to organic methyl mercury Environmental global environmental contaminant Recommendations avoid, recycle mercury-containing devices... 

Recommendations avoid, recycle mercury-containing devices... 

Based on 1995 estimates, the cost for the removal of a hot spot with dimensions 40 ft by 60 ft by 10 ft deep with the grouting extending 10 ft beyond the hot spot was estimated at 3,295 million. These costs could double or triple based on the project management, the need for containment devices other than weather shields, health physics support, and sampling required during cleanup operations. No cost estimate is provided for treatment and final disposal (D13730E, pp. vi, 120). Details of the cost estimates are given in Table 3. 

Flare, Parachute, Hand Fired. A complete self-contained device which is fired from the... 

Consideration of sample preparation also leads to the question of whether for some applications at least sensors would be more effectively constructed as a collection of modules each with a different function (sample preparation, transduction, detection, data collection) on a platform, large, small or miniaturised, rather than the old ideal of a small, self-contained device with intimately appressed layers which could return a rapid answer from a bucket of slime or some other spectacularly heterogeneous matrix. It is accepted that those with a taxonomic bent... 

Capture devices Fume hoods and other open-face containment devices are not permitted for production and pilot plant scale (e.g., greater than 5 kg powder or 100 L liquid) Fume hoods and other open-face containment devices are to be considered for kilo-scale (e.g., less than production/ pilot plant-scale and greater than 1 kg powder or 22 L liquid) Fume hoods are acceptable with a face velocities of 80-120 fpm (0.4-0.5 m/s), or other containment measures (e.g., snorkel). Weighing hoods should maintain manufacturer-recommended face velocity for small scale (e.g., less than kilo-scale)... 

Equipment testing Ventilation testing to ensure proper function and operation required. For containment devices, factory acceptance testing and site acceptance testing should be completed... 

Vapor barriers can be considered containment devices as they are useful in retarding the dispersion of vapor clouds, and have already been alluded to in Section 5.2.1. 

Fig. 7.28 By placing a Toepler pump (or any mercury-containing device) in a plastic container, spills are avoided and it s protected from an accidental bump.

Exhaust air from primary containment devices (fume hoods, safety cabinets or other) shall be appropriately treated by filtration using a high efficiency particulate air filter (HEPA), or by adsorption, absorption, reaction, incineration, or dilution used individually or in an appropriate combination. If HEPA or charcoal filters are used, these must be installed and operated to permit decontamination, maintenance, and replacement without exposing personnel or causing contamination of the environment. 

---