scheme of the central pressure inlet system
Scheme of the central pressure inlet system is shown in Fig. AO. There is central air intake imposed outside the industrial site, a central plenum chamber of the filtration and Air Heater units (or only with Air Heater) and discharge veins shlya mountains (usually one fan is working, and the second backup). Processed in the chamber air is diluted by building through the main channels of pressurized and supplied to consumers with pressure sufficient to overcome the resistance of the internal distribution networks. Such a system is in the full sense of the word central, because there are air treatment and motivation of its movement produced a single unit. Breeders channels typically run underground in reinforced concrete, lined the inside smooth tiles. Channels often continuous.
Air velocity in ducts to reduce the size of their take from 12 to 20 m / sec. This causes a rather large loss of pressure, so at a speed of 20 m / s the resistance of channels ranging from 150 to 250 kg/m2.
A variant of the pressure system is a device with a central fan and local air heater. In this case, the central Air Heater Installation is replaced by several local, have in the service buildings.
Performance of the central pressure systems varies between 200 and 000 to 800 000 m3 / h. Larger systems are relatively rare. As a driving force applied axial mine fans.
Air intake is a separate booth with louvered grilles, at a height of 3-4 m above ground level. Air intake is desirable to have in the area of green space to windward against the prevailing winds of the cold period.
The disadvantage of the central pressure systems are: a great loss of pressure (up to 300 kg/m2), a significant leakage of air through the inevitable looseness of the channel (20-25%), loss of heat from the cooling channel in the central Air Heater Installation.
Suction central air supply system to some extent free from these nedostatkov.Shema central inlet suction system is shown in Fig. 31. It also has central air intake imposed outside the industrial site to the zone of greenery. From the air intake to the suction channel of air enters the central chamber, where n is filtered hot. Then, the suction channel of the same air enters the building through the dilution created by the local fans. Local fans - usually centrifugal - delivers air to the places of its consumption on the internal pressurized networks.
In this system the air moves from the air intake to any fan in the building due to dilution caused by this fan. In the external pressure areas are absent, resulting in loss of treated air is excluded. Cellar in the system pressure decreases,
hook as suction channels can be made larger sections. In case of disconnection of a ventilator at each branch to the building should be a check valve.
Alternatively, the suction system can be installed, in which the heaters are located in buildings shared with fans.