Types of air filter

The air filtration manufacturer has seen its share of changes over the last decade. They have created new products that not only have improved indoor air quality but also have reduced the cost of installation. When the American Society of Heating, Refrigeration, and Air-conditioning engineers introduced IAQ standards for an air filter. Among these several types of air filters are common in common HVAC systems. 

Different types of air filter: 

Fibreglass filter: This is the most common type of air filter. Layered fibreglass fibres are laid over each other to form the filter media and reinforced with metal supports to prevent failure. 

Polyester and pleated filter: This filter is similar to fibreglass filters but typically have a higher resistance to airflow and a superior dust stopping ability. 

Washable air filter: This filter is not common and relies on the build-up of dust along the clothes to improve the efficiency of a filter. 

High-efficiency particulate arrestance (HEPA) filter: Air passing through this filter at a very fine scale. The US department of energy (DOE) use this filter that meets standards. 

Carbon air filter: Carbon can be treated with oxygen, which opens the carbon's pores making it highly absorbent. It uses activated carbon to trap chemicals and gases, and can also filter cigarette smoke. These activated carbon air filters are well suited to an environment where chemical must be removed from the air. 

UV light air filter: This filter use reaction that occurs when titanium dioxide is exposed to UV light. As the air stream encounters the photochemical process, harmful particles, such as mould and bacteria, are neutralized. 


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• Difference between the air filter and cabin filter

Difference between air filter and cabin filter

Both air filters and cabin filters purify the air but their purpose is slightly different. The air filter cleans the air that flowing to the engine while cabin filter decontaminate air coming into the cockpit. It's important to recognize the distinction between these two filters so in this article you can check it out some difference between the air filter and cabin filter. 

Difference between the air filter and cabin filter : 

• The air filter is often a performance upgrade, while the cabin air filter is more of a health and safety concern. 
• The air filter is located in the engine bay under the hood inside a sealed box and is one of the important components of the engine whereas the cabin filter is located behind the glove compartment, under the dash and under the hood. 
• The air filter prevents dirty air from getting into the engine while cabin air filter blocks dirty air from getting inside the cabin. 
• Some old vehicle with carburettors has a big metal air filter that located in a round, bulky case made of plastic or metal whereas some vehicles have the air filter installed inside the HVAC case between the blower motor and evaporator core. 
• The air filter prevents the bugs, dirt, debris and contaminants from entering the delicate system of an engine and allows the only pure air in and the cabin air filter blocks all the airborne allergens and other pollutants from entering the ventilation system of the vehicle. 
• If the air filter is not replaced and allowed to block up, it can increase fuel consumption and place additional strain on the engine and driveline components whereas failure to replace the cabin air filter may cause a musty smell to emanate through the air conditioning system, and make car trips unpleasant, especially on hot days.
• Due to a bad or clogged air filter, the turbo life of vehicle gets minimized whereas cabin filter only passes to clean air to the vehicle. 

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• Types of the air filter

Porter Governor | Construction | Working | Equation of height

Porter governor is same as Watt governor. If the watt governor sleeve is loaded with a heavyweight, it becomes a Porter governor. 

Let M = Mass of the sleeve
m = Mass of each ball
f = Force of friction at the sleeve

Porter Governor

The frictional force always acts in the opposite direction to the motion, so when the sleeve moves up, the frictional force acts in the downward direction, and the downward force acting on the sleeve is Mg+f. Likewise, the force on the sleeve will be Mg-f when the sleeve moves down. Depending on whether the sleeve is going up or down, the net force acting on the sleeve is mg+f or Mg-f.

Forces acting on the sleeve and on each ball have been shown in the figure. 

Let h = height of the governor
r = distance of the centre of each ball from the axis of rotation

The instantaneous rotation centre of AB link is at I. It is because of the motion of its two points A and B relative to the link. The point A oscillates about the point O and B moves in the verticle direction parallel to the axis. 

Now, the equilibrium of the left-hand half of the governor and taking moments about I. We equate the equation form given below to find the height of governor. 

N² = 895/h × [ 2mg + ( mg + or -  f ) ( 1 + k ) / 2mg ] 

This equation would provide two values of N for the governor for the same height depending upon the sleeve movement.  

Advantages and disadvantages of worm gear

Worm gear drive is used to transmit power between two non-intersecting shafts, which are at right angles to each other consists of a worm and a worm wheel. The worm is a threaded screw, while the worm wheel is toothed gear. The teeth on the worm wheel envelope the threads on the worm and give the contact between mating parts. Let us have a deep insight into the benefits and drawback of the worm gear in this article. 

Advantages of worm gear : 

• High-speed reduction: A speed reduction is as high as 100:1 can be obtained with a single pair of worm gear. 
• The worm gear is compact with small overall dimensions, compared with equivalent spur or helical gear drives having same speed reduction. 
• The operation is smooth and silent. 
• Provision can be made for self-locking operation, where the motion is transmitted only from the worm to the worm wheel. This is advantageous in application like cranes and lifting devices. 
• The worm gear has good meshing effectiveness.
• The worm gear used for reducing speed and increasing torque. 

Disadvantages of worm gear : 

• The efficiency is low as compared with the other types of gear drives. 
• The worm wheel is made of phosphor bronze, which increases the cost. 
• A considerable amount of heat is generated in worm gear drives, which is required to be dissipated by a lubricating oil to the housing walls and finally to the surroundings.
• The power transmitting capacity is low. 
• It is used for up to 100 kW of power transmission. 
• Lubrication must be strictly maintained for the healthiness of worm gear. 

Difference between welding and fabrication

Welding and fabrication both are two essential processes in the metal industry. In this article, you can check it out the difference between both of these processes so let start with the definition first. 

Definition of Welding : 

Welding is a process which usually involves metals or thermoplastics by inducing melting, which is distinct from lower temperature metal joining processes such as brazing and soldering that do not melt the base metal. Welding is essentially a combination of two pieces, no design, no layout or cutting.

Definition of Fabrication : 

Fabrication is the building of metal structures by cutting, bending, welding and assembling processes. Fabrication is the process of manufacturing or inventing something. Fabrication is making something while welding is only one operation performed during the process. 

Let us have a deep insight into the difference between welding and fabrication below. 

Difference between welding and fabrication : 

• Fabrication of metal refers to the build of metal structures and is carried out through a variety of processes such as cutting, bending, profiling, welding and assembling whereas the prepared metal from fabrication process then welded together using a variety of techniques and methods frequently involve arc, power supply in order to create an electric arc between electrode on the welding rod and the material itself. 
• The difference between welding and fabrication is that welding is a particular method of making something by using heat to join together the metal pieces, and fabrication is creating something and does not usually use heat.