Airflow systems

Airflow Systems, Inc Resource for the collection and filtration of dust, smoke, mist, fumes and other airborne contaminants generated during industrial and commercial manufacturing and processing applications. http., llwww.air, flowsvstems. com... 

The redesigned airflow system, consisting of a broader air curtain (the broadness needed also for other reasons) and a local exhaust below the oven, ensures class A air quality in the oven when the door is opened for (see Fig. 11.3). 

If the results of the preceding three steps are unsatisfactory, the laminar-airflow system cannot be validated and the rest of the validation tests should not be carried out until a satisfactory operation has been reached. Otherwise, the system is valid and can be certified. 

The combustion and airflow system in an automobile delivers a fresh charge of air and fuel into the combustion chamber and then converts the chemical energy into mechanical energy by the combustion process. Equation 7.1 shows how the process works ... 

Laminar-airflow systems should provide a homogeneous air speed of about 0.30 m/s for vertical flow and about 0.45 m/s for horizontal flow but precise air speeds will depend on the type of equipment... 

The fraetion of moleeules on the filter paper that was released per s, given an airflow of 100 ml/s, was determined with loads of 10 to lO " g/f p The fraetion was 1/60,000 at 10" and 10" g/f.p. This value was extrapolated for the load at the behavioural threshold. In our setup the eoneentration of stimulus molecules decreased on the way from the outlet of the airflow system to the antenna. The fraction of molecules released from the filter paper that was adsorbed on the antenna was 1/150, determined with loads of 10 g/f.p., or higher. 

FIGURE 14.34 Solar-assisted indirect drying system for alfalfa (a) scheme of system (b) reduced mass flow network model of the fluid (c) reduced mass flow network model of the airflow system. 

The basic airflow system for flotation dryers is shown in Figure 46.10. It consists of three baac components (1) supply fan ... 

Since none of the air that has passed through the work zone is recirculated, at least in principle, this type of cabinet could be used for moderate chemical appUcations. However care would have to be taken to ensure that the exhaust filter would not suffer from loading of the filter by chemicals. The different rates of loading of the Met and exhaust filters are a problem for all types of Class n cabinets, but the more compUcated airflow systems of Class IIB biosafety cabinets, where two or more blowers are involved, exacerbate the problems. 

If the solvent concentration of a zone exceeds certain level, then the system becomes to be in danger of explosion due to the flammability of organic solvent vapor. This level of solvent concentration is called as lower explosive level (LEL), and the dryer should be operated below the LEL prior to any constraints. Thus each zone needs sufficient airflow rate to meet these needs. However, too much airflow rate results in waste of energy to heat the excess air, and it increases the load ofwaste gas facilities (e.g., VOC emission control units). Therefore the airflow rate of each zone and the ratio of recycled to fresh air should be optimized. The typical airflow system for a multiple zone dryer is shown in Figure 7.3.32. The supplying air of each zone is consisted of fresh and recycled (used or returned from the exit gas) air as shown in the figure. LEL can be calculated if we know the evaporation rate of solvent of a zone. The evaporation rate of solvent can be measured or calculated as we explained in previous sections. Thus we can distribute the fresh air to each zone to meet the LEL safety without substantial increase in the total exhaust air. 

Figure 7.3.32. Schematic diagram of airflow system to a zone. [After reference 30].

E-Z Arm, Mechanical fume/dust arm extractor, Airflow Systems, Inc. 

Another type of system used in manufacturing is based on carbon adsorption. The exhaust stream passes through a carbon bed and the VOCs are adsorbed by the carbon particles. This is one of the most cost-effective systems, but it only works well with very low concentrations of VOCs in the stream, and the efficiency tends to decline with use. As the carbon bed becomes filled with solvent(s), it may also experience bed plugging, which decreases removal efficiency and can present a fire hazard. In addition, back pressure can cause problems with the airflow system in the tape casting drying chamber. The carbon bed must be periodically reactivated either by firing or by steam stripping, both of which can be costly maintenance operations. 

The basic airflow system for flotation dryers is shown in Figure 40.10. It consists of three basic components (1) supply fan (2) exhaust fan and (3) heater. The supply fan is sized for the air volume required by the open area of the dryer nozzles and the maximum nozzle outlet velocity. It blows hot air through the air-bar nozzles onto the coated web surface. The spent air is exhausted by an exhaust fan. The heater can be a direct-fired gas burner for air temperatures up to 400°C or high-steam coils for air temperatures up to 200°C. When drying aqueous coatings, the exhaust is led to a recirculation system where part is bled to the atmosphere and the remainder reheated for recirculation. When solvents are involved, this spent air may be incinerated or led to a solvent-recovery unit. 

Figure 4.14. Flow control for sheathed airflow system.

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