Gas-driven Machines

Mechanical engineering is a wide field of study. Fluid machinery is one of its most important subjects. Fluid machineries are machines in which fluid is their medium to transfer work. In studying fluid machineries, you must be aware that they are classified according to the types of fluids they used whether liquid such as water and oil, or gas such as air.
In the study of fluid machineries, when we talk about gas, it does not mean a gasoline or a fuel. Gas often pertains to air and other gaseous substance.

Fans and Compressors

Fans and compressors are two common types of fluid machineries that use air as their working medium. Do not get confuse with these two fluid machines. Take note that they work on different pressure difference.

Fans 

Fans are used to control the air movement in a low pressure, commonly at less than 10psi. Typically, a fan is sub-divided into two groups namely blowers and exhausters. A blower is a form of fan in which the air is being driven out to the surroundings through the discharge part of the system. On the other hand, an exhauster is a fan that works in opposite way the blower do. Exhauster is used to withdraw air from the surrounding through its suction part.

Fan performance

In studying fluid machineries, you should know the following concepts of fans:

• Fan static pressure head – the height of the fluid’s surface to the gauge point.
• Velocity head – head necessary to produce the flow of air.
• Total head – the sum of the static head and velocity head of the fan.
• Capacity of a fan – product of the fan area and velocity; the volume flow rate of the air.
• Air power or power output of a fan – power produced by the fan. 
• Brake power or power input to the fan – power being input to the fan usually from a motor.

Compressors

Compressor is also a fluid machine that used to increase air pressure (greater than atmospheric pressure) by decreasing its volume. Compressors, which are commonly powered by electric motor, are typically used in industrial applications that require air or other gases at high pressure. Compressors have two major classifications:

• Positive displacement compressors – these compressors have two types: the reciprocating, which are commonly used in internal combustion engines, and the rotary screw, which are often used in commercial applications. 
• Dynamic compressors – these can be classified as to centrifugal and axial flow compressors. 

Introduction to Welding – Modern Welding Methods

Welding is considered as sculptural or fabrication procedure what joins materials, normally thermoplastics or metals, by creating coalescence. This is often performed by liquefying the workpieces as well as incorporating a filler stuff to develop a puddle of molten substances which cools to turn out to be a powerful joint, sometimes with pressure utilized in combination with temperature of by itself for producing the weld. This is in disparity with brazing and soldering that comprise liquefying a lower melting point substance amid the workpieces to create a link among them, without liquefying the workpieces. Several different energy sources could be utilized for welding, comprising an electric arc, a gas frame, a laser, friction, ultrasound and an electron beam. Whilst most of the time an industrial procedure, welding might be done in several different atmospheres, comprising under water, open air, as well as within outer space.

Potentially welding is dangerous undertaking and safety measures are necessary to ignore electric shock, burns, vision damage, gasp of toxic fumes and gases as well as contact to intense ultraviolet emission. Till the conclusion of the nineteenth century, the lone welding procedure was forge welding, what blacksmith has utilized for centuries for joining steel and iron by heating as well as hammering. Oxyfuel welding and arc welding were amongst the 1st procedure to expand late towards the century, then electric resistance welding followed it. Technology in welding advanced very swiftly throughout the early twentieth century since World War I as well as II gaggle the requirement for inexpensive and reliable joining process. Following the war, different contemporary welding technologies were come into action.

Let’s have a look at the different types of modern welding methods available:

Shielded Metal Arc Welding

Known as stick welding that utilize a bar or in technical term it’s called an electrode which has a residue coating over it that melts or burns to develop a screen from oxygen, and few bars have packing metals incorporated to the wrapping to accelerate the welding procedure. Shielded metal arc welding is considered as the ideal procedure to weld outdoors.

Metal Insert Gas Welding (MIG)

MIG welding is a procedure which utilizes a wire pool for feeding wire to the joint as well as has a container of gas which gushes from the appliance to the welding grip to shelter the weld form air about it. The greatest portrayal in an assessment perspective is a cycle’s brake wire that has a cable running through which feeds incessantly to the joint, however; also this cable has a gas streaming via it that protects the weld from the air.

Tungsten Inert Gas Welding 

Also known as TIG welding is a torch which has a gas streaming through with a non delicate bar created from tungsten which warmth the metal as well as the packing metal is detained in other hand and physically incorporated when required. The non-consumable bar is only a bar that makes the arc to warmth the metal. It doesn’t put in to the welding packing material itself.