Technology and performance parameters of vacuum cleaners
A difference in air pressure causes suction in a vacuum. The fan reduces the pressure inside the machine which is driven by an electric motor. The Air then is pushed by the atmospheric pressure through the carpet and into the nozzle, and so the dust is literally pushed into the bag.
Bag: It is the most common method to capture the debris vacuumed up by involving a paper or a fabric bag that will allow the air to pass through, but attempts to trap most of the dust and debris. Usually, the bag is disposable. However, some models involve a bag that can be cleaned and re-used.
Bagless: In these models there is no bag attached. The role of the bag is taken by a removable container and a reusable filter, equivalent to a reusable fabric bag. These are non-cyclonic bagless models.
Cyclonic Separation: Bagless models employ this method. It causes intake air to be cycled. As a result, most of the dust is forced out of the air which then falls into a collection bin.
Water Filtration: Water filtration vacuum cleaners use a water bath as a filter. It forces the dusty air to go through water before it is exhausted. It causes the wet dust not to become airborne. The water trap filtration and low speed can also allow the user to use the machine as a stand alone humidifier and air purifier unit. Users must dump out the dirty water and clean the appliance after each use to avoid pleasant odor caused by the growth of bacteria and mold.
Ultra Fine Air Filter: This is widely known as HEPA filter. This method is used as a secondary filter after the air passes through the rest of the machine. It is meant to remove any remaining dust and prevent the user from inhaling harmful dust. Some vacuum cleaners also involve an activated charcoal filter to remove odors.
Most vacuum cleaners have specialized attachments, such as tools, brushes and extension wands. These tools allow them to reach hard to access places or to clean a variety of surfaces. The most common of these tools are:
• Hard floor brush
• Powered floor nozzle
• Dusting brush
• Crevice tool
• Upholstery nozzle
Parameters to measure the performance of a vacuum cleaner:
• Airflow ( in litres per second or cubic feet per minute)
• Suction, vacuum, or water lift (in pascals or inches of water)
• Air speed (in metres per second or miles per hour)
• Weight in kilograms or pounds
• Noise in decibels
• Power cord and hose lengths
Vacuum suction is the maximum pressure difference that the pump can create. A typical domestic model has a suction of about negative 20 kPa. It means, it can lower the pressure inside the hose than normal atmospheric pressure (about 100 kPa) by 20 kPa. If the suction rating is high, the cleaner will be highly powerful too. 1 inch of water equals to about 249 Pa; Therefore, the typical suction is about 80 inches (2,000 mm) of water.
The power consumption of a vacuum cleaner is usually the only figure stated. Many vacuum manufacturers give the current only in amperes (e.g. “6 amps”) and the users is left to multiply that by the line voltage of 120 volts to get the approximate power ratings in watts. The rated input power is non-indicative of the effectiveness of the cleaner. It only says how much electricity it consumes.
The amount of input power which is converted into airflow at the end of the cleaning hose is usually measured and stated in airwatts. The word “air” means that this is output power and not to mean input electrical power.
Airwatt is defined by ASTM International as 0.117354 * F * S, where F is the rate of air flow in ft3/min and S indicates the pressure in inches of water. This will make 1 airwatt equal to 0.9983 watts.
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