Fixed ventilation systems

All local ventilation systems can, in principle (and many are in practice), be manufactured for use in one or more of three different modes fixed, flexible, and mobile. 

The primary components of LVHV ventilation systems are the exhaust nozzles, flexible hose, fixed duct, air cleaner, and the exhauster and motor. Each of these is discussed below. Figures 10.23,10.27, and 10.28 illustrate LVHV nozzles. Figures 10.29 and 10.30 illustrate other system components and installations. 

Wet or dry chemical fixed suppression systems are typically provided over the kitchen cooking appliances and in exhaust plenums and ducts. Activation means is afforded by fusible links located in the exhaust ducts/plenums usually rated at 232°C (450°F). Manual activation means should not be provided near the cooking area, but in the exit routes from the facility. The facility fire alarm should sound upon activation of the fixed suppression system and power or gas to the cooking appliances should be automatically shut off. The ventilation system should also be shut down by the activation of the fire alarm system. Protective caps should be provided on the suppression nozzles to prevent plugging from grease or cooking particulates. 

In this section, we present some of the commercially available detectors for CWAs and toxic chemicals that are based on IMS or DMS. These include a large variety of devices ranging from handheld, or even pocket-size, instruments to larger fixed-point monitors that can even be placed in the ventilation system of buildings. The devices mentioned here are for demonstration purposes and are not to be understood as recommended by us. 

At least in high-risk areas (where pure chemical carcinogenic substances are handled), the ceiling must be of one piece, impermeable and fixed to the walls, so that the only connections between the whole room, and neighbouring laboratories or corridors are the door, the ventilation system and the hood exhaust. 

The plutonium inventory monitoring system (PIMS) is a network of 142 He neutron detectors in moderating enclosures, which are installed in a plutonium-powder process area at fixed positions outside of process glove boxes and the ventilation system (Simpson et al. 1998 Parvin 2007 Whitehouse et al. 2004). The collected neutron counts are processed in a matrix approach to image the neutron field of the process area. Any change to the in-process inventory will be detected and can be accounted for on a near real-time basis. The PIMS will also be used to verify the clean out and to measure any residual material. The PIMS is operator-owned equipment used jointly with the inspectorate. Appropriate authentication measures are therefore in place to validate the measurement results. 

If the exhaust of the Radwaste Building Ventilation System is discharged directly to the environment, this monitor is located in the exhaust and includes a particulate/iodine fixed filter cartridge in the sample tube inlet and normal and high range gas detection channels. 

Stone, brick, and concrete cutting or chasing of concrete to install conduits can utilize water sprays on cutting wheels as a control technique. If this is not possible, effective fixed or portable ventilation systems can be connected to the tool, which include a suitable movable spring loaded hood. 

The United States needs to improve and expand the uses of sensors in preventing terrorism and to minimize the impact should an incident occur. Besides point sampling devices, sensors to help provide sensitive and rapid detection and advance warning of toxic vapor at fixed sites such as subways, buildings, financial centers, and airports are of utmost importance. These sensors need to be operable around the clock. For example, sensors installed in the ventilation system could be coupled with a rapid shutdown procedure. Portable sensors to allow assessment from a remote or on-site point can be used to map the potential extent of the chanical cloud cover to aid authorities in organizing the movement of people. Current sensors have limited capabilities and must be improved. 

It is possible that some transmitters are rather quickly released. In that case, we recommend preparing the tissue in fixative on ice if you have the possibility to remove the developing vapor by an exhauster/ventilation system. 

Commercial products do exist that integrate shrouded and ventilated grinding wheels and other hand-held tools. It may be possible to find an existing LVHV-type product that will work well for some applications, requiring only to be connected to an appropriate air handling system. However, it is also sometimes necessary to make custom-fabricated LVHV nozzles for some hand-held tools and for essentially all fixed-machine dust-generating tools. I he best approach is to consider the following ... 

There are a variety of UV air disinfection systems. Generally, they can be classified into upper-air systems and in-duct systems according to different installations. Upper-air systems are installed at an upper position of a room, where the UV units can be movable or just fixed to room wall, ceiling, or inlet/outlet of air recirculation systems. However, because the air flow and current in upper-air system is usually uncontrolled, it is difficult to establish a theoretical prediction model. In most cases, empirical models are often used. Furthermore, high UV exposure risk to personnel is a concern with upper-air systems. In-duct systems are installed in a ventilating or air conditioning system, where air flow rate, flow paten, and temperature are more easily controlled. 

The primary air is blown with an automatic ventilator through holes in the grate into the glowing fire. The secondary air is blown at the top of the burning fuel. The air feeding system adjusts itself automatically according to information from a sensor fixed in the flue gas outlet, minimizing pollutant emissions. No additional flue gas treatment is needed and ash can be used as a fertilizer or put on a landfill site. 

---