Airlock

Dried product is collected in either cyclones or baghouses depending upon the product-particle size. When primary coUection is carried out in cyclones, secondary collection in a baghouse or scrubber is usually necessary in order to comply with environmental regulations. A rotary valve is used to provide an airlock at the discharge point. Screws are utihzed to combine product from multiple cyclones or large bag-houses. If required, a portion of the dried product is separated from the main stream and returned to the feed system for use as backmix. 

FIG. 17-60 Reverse-pulse fahric filter (a) filter cylinders (h) wire retainers (c) collars (d) tube sheet (e) venturi nozzle (f) nozzle or orifice (g) solenoid valve (h) timer (/) air manifold (k) collector housing (/) inlet (m) hopper (n) airlock (o) iipperplenum, (Mikropul Division, US. Filter Coip.)... 

Charge solids materials by means of a closed system (e.g., hopper and rotary airlock, screw feeder, double-dump valve system, etc.)... 

Operator exposure Charge liquids and solids materials by means of a to fumes or inerts. closed system (e.g., hard piping, hopper and rotary airlock, screw feeder, double-dump valve system, etc.) Provide local ventilation Use proper personnel protective equipment (PPE) ACGIH 1986 CCPS G-22 CCPS G-23 CCPS G-29... 

Use barrier technology (closed system airlocks, charging vessels, etc.)... 

To get equipment and the material to be treated into and out of the box it is necessary to have some kind of door. This door should be made in such way that it tightens when negative pressure is applied inside the box. Instead of one door, an airlock volume with one door to the box interior and one door to the exterior can be used. 

Airlock A two- or three-door enclosure providing access to a clean room that reduces the air leakage of external pol luted air into the clean room. 

Airlock, active An airlock connected to an air treatment device. 

Airlock, passive An airlock that is nor connected to the air conditioning system. 

Elame propagation can also be stopped between process eqnipment handling bnlk solids and powders by jndicions selection and design of bnlk solids/powders conveying eqnipment snch as rotary valves (rotary airlocks) and screw conveyors. The mass of bnlk solids/powders contained in these items of eqnipment provide a tortnons path throngh which the gas and flame have to pass, and so can act as a material choke when certain design features are implemented. 

Schleuse,/. sluice sewer airlock. Schleusengas n. sewer gas,... 

The opportunity is taken, while filling for testing, to ensure that the circuits can be filled without airlocks. Air vents at high points of the circuit may be automatic or manual. While the pipes are full, pumps should be run if possible to dislodge any dirt before draining down and cleaning the strainers. If a lot of dirt is found, the pipework should be filled again and reflushed. In any case, the pumps should be run at the earliest opportunity and the strainers cleaned out. 

To avoid ingress of warm air (and loss of cold air) it is useful to have an airlock. However, these need to be at least the length of a loaded fork-lift truck, and the extra space required, together with the double doors and extra movement time, should be investigated closely before such an arrangement is put into use. 

Warm air will enter from outside mainly during the opening of doors for the passage of goods. This must be estimated on the basis of the possible use of the doors, and such figures are based on observed practice. The parameters are the size of the store, the enthalpy difference between inside and outside air, and the usage of the doors. The latter is affected by the existence of airlocks and curtains [49]. 

Thermal-programmed solid insertion probe mass spectrometry (TP-SIP-MS) has been proposed [247,248], in which the solid insertion probe consisting of a water-cooled microfumace enters the mass spectrometer via an airlock. The sample is contained in a small Pyrex tube (i.d. 1 mm, length 20 mm). The TIC trace gives a characteristic evolved gas profile for each compound in a mixture of materials, and the mass spectra associated with each TIC peak give a positive identification of that component as it is vaporised. TP-SIP-MS is appropriate for analysis of small solid particles which are volatile, or produce volatile decomposition products. The technique is a form of evolved gas analysis. 

The specimen stage usually holds several specimens and standards, with dimensions typically 20-30 mm, although for special purposes extra-large specimen stages are available - Matsuya et al. (1988) describe a holder with a working area of 300 x 300 mm. An airlock isolated from the main vacuum chamber reduces the time taken to change specimens. 

All the systems must have a means of bringing the solids and the gas stream together. Since the gas is under either vacuum or pressure, some sort of airlock is needed in order to prevent air either from being sucked into the system or from being blown into and through the feeding system. The most common solution is a rotary valve (see Fig. 8-9) driven by a motor. 

After the material reaches its destination, the gas and solids must be separated. When this is done in a cyclone separator (see Fig. 8-10) the gas stream enters a large container from the side tangentially. The solids are thrown against the side by centrifugal force, fall under the force of gravity, and exit through the bottom. The gas exits at the top. Again some type of airlock is needed to remove the solids. One... 

High Pressure Airlock Waeschle, Fuller, Allied Flotronics Fuller Kinyon Pump Fuller... 

Sometimes in the design of a BSL-4 facility, the full letter of health and safety codes/requirements for the protection of workers can not be met. This is where health and safety specialists must compromise and use their ingenuity to meet the intent of the requirements. For example, it is not always possible to provide a secondary means of egress from each area. Two change facilities are not cost effective or practical. A viable alternative is the use of airlocks with built-in liquid disinfection systems which are not hazardous to humans, but destroy the biohazard. These airlocks must be clearly identified as others are often used for transportation of equipment and other materials and contain hazardous disinfection systems. 

Laboratory rooms intended for toxic work should be provided with adjacent shower and change facilities. The layout must not require freshly showered personnel to track back through the area that they might have just contaminated. All drains, including those in laboratory floors, should have deep traps and be directed to a toxic sump. Airlocks will help prevent toxic fumes from spreading to non-toxic areas in the event of a failure of a primary containment cabinet. Check valves in the incoming water lines will prevent contamination of potable water supplies when pressure is lost. 

Nose/mouth only Exposure limited to mouth and respiratory tract Uses less material (efficient) Containment of material Can pulse the exposure Stress to animal Seal about face Effort to expose large number of animals Pressure fluctuations Body temperature Sampling Airlocking Animals comfort Losses in plumbing /masks... 

Heady stuff I examined pictures of the large and futuristic inflatable MUST units. Their design was both ingenious and functional. Each unit consisted of a series of semi-circular, air-filled cylinders, creating a structure that looked like an enormous green barrel, half buried in the sand. Each had an airtight airlock entrance. 

Generally negative pressure with respect to adjacent areas Material and personnel airlocks should have overpressure with respect to adjacent areas (e.g., corridors) Continuous monitoring of pressure differences (about 10 to 15 pa)... 

At the cross point between nonclassihed and classihed areas, as well as between the different classihed areas, separate airlocks for materials and personnel should be installed. Additionally, airlocks to the clean or to the aseptic areas should be equipped with interlocking doors. Only authorized personnel should be allowed to enter the classihed areas. 

Clean room personnel gowning room Airlock (formulation materials entrance and... 

AREA Coding room Room No. (Class 10,000/100,000) Reference sampling point Unloading autoclave Room No. (Class 1000/10,000) Ref ence sampling point Material,Airlock Room No. (Class 10,000/100,000) Rekrence sampling point it Personnel Airlock Room No. (Class 10,000/100,000) Reference sampling point ... 

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