## Hydraulic Coefficients

In Fluid dynamics, the following four coefficients are known as Hydraulic Coefficients.  They are Coefficient of Contraction This is the ratio of the area of the jet at Vena Contracta to the area of the orifice. Coefficient of Velocity This is the ratio of the actual velocity of the jet at vena contracta to the …

## Hydrostatic Pumps

A hydrostatic pump is also known as a positive displacement pump.  In a hydrostatic pump, the volume of liquid discharged per cycle is constant.  In hydrostatic pumps, the liquid is drawn in to a chamber and then discharged.  A reciprocating pump with a piston and a cylinder is an example for a hydrostatic pump.

## Velocimetry – An Overview

Velocimetry refers to the study of the flow of fluids.  It is very important in the field of fluid dynamics and in the design of equipments, such as, pumps and turbines.  The flow of liquids can be studied by adding small materials such as bits of paper or styrofoam in water.  This helps the observer …

## lbs. the symbol for pound

The pound, which is a unit of weight, is indicated by the letters lbs.  lbs comes from the latin Libra which is a short form of Libra Pondo (trans. a pound by weight).  This was a unit of weight used in the Roman empire.   Over time, the libra got shortened to lbs.

## Bar in pressure measurement

The bar is a very common unit of pressure.  It is used in the industry for normal operational measurements. It is popular as one bar is approximately equal to the normal atmospheric pressure (slightly lower, 0.987 atmosphere).  This helps people to visualize the pressure easily. A millibar is 1/1000th of a bar.  A bar is …

## Pounds per square inch (psi)

Pounds per square inch is a very common unit of pressure.  It belongs to the Imperial System of measurement.   It is widely used in industries, tyres and other applications.  The unit indicates that the pressure is equivalent to a certain number of pounds applied to a square inch of area.   There are two variations of …

## Welding Slag

Welding flux is used to protect the weld area from contamination.  The flux forms a protective layer over the surface.  In certain cases, it is left as a residue over the weld area.  This is called welding slag. Welding Slag has to be removed in order to be able to view the welded area for …

## Shielded metal arc welding

Shielded metal arc welding is one of most popular methods of welding.  Shielded metal arc is simpler than other forms of welding.  It requires an welding transformer kit and an electrode.  Shielded metal arc welding works by creating an electric arc between the work piece and the electrode. The welding transformer can produce high currents.  …

## Welding Flux

Welding flux is a substance used during the welding process to shield the weld area from atmospheric contamination.  In metal arc welding, the flux is part of the welding rods.  When the arc is initiated, the high temperature melts the work piece and the welding rod.  The flux coating on the rod also melts and …

## Porosity in Welding

Porosity in welding is the formation of air pockets or bubbles in the weld area.  Porosity makes the weld weak and can cause failure of the weld area.  Some of the causes of porosity are Improper shielding Presence of water or moisture on the weld surface Presence of paint, which can get vaporised during the …