Systems of Ventilation are:

(i) Natural Ventilation.

(ii) Mechanical/Artificial Ventilation Extraction system supply pressure system.

(a) Inlet.

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(b) Extract.

(c) Combined supply Inlet & Extraction system.

(d) Plenum Process.

Water Wash Ventilating Unit Series:

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Green dust lint is centrifugally collected. A series of baffles inside the unit located along the path of air forces the air to make a successive of rapid turns causing heavier than air partially to be thrown out of the stream by centrifugal forces.

These particles then collected in a grease collecting gutter at the bottom of ventilator, they are removed by cleaning with hot detergent water.

The plumbing enclosure cabinet is located on the wall near the ventilator. The water line from this cabinet is connected to the ventilator. When the stop button is pressed on the enclosure cabinet, it shuts off the exhaust fan; the hot water and detergent are then pumped to the ventilator for the wash cycle. The components of the cabinet are as follows:

i. Shutoff valve:

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This valve shuts off the main water line (it is normally open).

ii. Line strainer:

The strainer prevents foreign particles in the water from folding ventilator nozzles.

iii. Solenoid valve:

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This valve controls water flow into the interior of the ventilator.

iv. Detergent tank:

The tank provides a holding area for 10 Kg. of detergent.

v. Pressure/temperature gauge:

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This gauge provides immediate readouts of water temperature and pressure.

vi. Exhaust control and cleaning station:

Pushing the STOP button on the control activates the cleaning cycle-turning off the exhaust fan, opening the solenoid valve to release water into the ventilator, and beginning the action of the detergent pump to inject detergent into the water line.

The hot detergent, injected water scrubs the interior of the ventilator throughout the time set by the operator on the timer within the control station. At the end of the present time, the water automatically shuts off. Pushing the RESTART button starts the exhaust fan.

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vii. Shock absorber:

The absorber prevents water hammer in the pipes.

viii. Detergent pump:

This electric pump provides positive injection of deter­gent into the water line, regardless of fluctuations in pressure and so on.

ix. Atmospheric vacuum breaker:

The vacuum breaker prevents contamination of the water supply by preventing the water and detergent from backing up into the main water supply line.

Maintenance of Ventilating Unit:

The maintenance required by this type of item consists mainly of a preven­tive maintenance program.

The detergent pump motor has a sealed lubrication system and requires. Care should be taken no, to spill detergent on the exterior of the pump.

Preventive Maintenance Schedule:

Daily:

i. Check the detergent tank, and keep it fully loaded with a recommended detergent

Weekly:

i. Open the inspection doors of the ventilator, and check to make sure that the interior is free of grease, dust and lint. If an area is not getting clean, one of the spray nozzles is probably clogged. Remove the nozzle in the area not getting cleaned, clean the nozzle orifice with a small ware, and replace the nozzle.

ii. Check the grease-collecting gutter, and remove any foreign material (such as paper towels) you find there.

Monthly:

i. Check the detergent system’s fittings, and tighten them if necessary.

Every six months:

i. Clean the detergent tank in accordance with the manufacturer’s specifica­tions.

ii. Clean the foot valve in the detergent tank.

iii. Check the exhaust fan for belt tightness, belt alignment, and proper oiling of necessary moving parts.

Systems of Ventilation:

(i) Natural ventilation:

Supply of outside air into a space through a win­dow or other opening due to wind outside and convection effects arising from temperature or vapor pressure difference or both between inside and outside of the space.

If space is wider than 30 meter then ventilation may be augmented by roof ventilation.

Inlet openings in the space should be well distributed and located on the wind ward side at a low level and outlet openings should be located on the tee ward side near the top. Height of window shall be kept 1.1m, width 2/3 of wall width.

Ventilation should be provided as close to ceilings. Ventilators can also be provided on roof – cowl, vent pipe, covered roof and ridge vent for stock effect. If the prevailing wind is from south then saw tooth roof is satisfactory. It is found that window ventilation with a combination of radiator, deflector and exhaust fan can give better results.

(ii) Mechanical/Artificial Ventilation:

Supply of outside air either by posi­tive infiltration, by reduction of pressure inside due to the exhaust of air or by a combination of positive ventilation and exhaust of air.

(a) Positive Ventilation Inlet:

The supply of outside air by means of me­chanical device such as fan. This air may be cooled by evaporative cooling or by air conditioning.

Positive ventilation is provided by centrally located supply fans.

(b) Negative Ventilation Extract:

Exhaust fans are provided in walls or in the attics and roofs to draw large volume of air through the space. These fans are of propeller type. Windows and other openings near to the fans are kept closed.

Inlets with total area of openings about three times the total sweep of exhaust fans should be provided in a wall opposite to the fans, when the fans are centrally located on an altic, they are of centrifugal/axial type.

This system is used when heat or odour is produced. Unit ventilators may be provided in individual rooms.

(c) Combined supply Inlet & extraction system:

Ambient fresh air is inducted inside by induction fans at one point and the foul air is extracted by exhaust fan at some other point. Sometimes, filters are used at the entry point of the fresh air for improving the quality of air and also for cooling it.

(d) Plenum process:

The incoming air may be allowed to pass through stream of water at the point of entry.

It may be employed by:

(i) Downward ventilation (ii) Upward ventilation

Ceiling fans 1500 mm sweep should be provided for every 6m x 6m of area.