Datum

What is Datum
A datum is an numerical or geographical quantity or set of such quantities. which may serve as a reference Of base for other quantities.In surveying datum is a set of quantities that describe the shape, size, rotation and gravity field parameters of the Earth.

Types of pumps

Types of pumps

When consider about the classification of pumps, They can be categorize according to their various types of behaviors and factors. So according to the application we have to select suitable pump by considering the behaviors and the requirements of the fluid which we have to control. 

            Generally we can classify the pumps types according to following ways as;

·         Mechanism of working

·         Power supply method to the pump

·         Transporting fluid type 

            So we should consider above factors one by one, when we selecting a pump for our application. By that we can select the most suitable pump available for our application, because some types are not suitable for every application. In some application we should have to use special types of pumps..

Classification according to the Mechanism of working

            This is the main classification method which use for pump classification. In this method pumps are classified according to the inside mechanism of the pump. So by that we can identify how the pump is functioning.

When we classify the pumps according to the mechanism, it is mainly divided into two parts as positive displacement and dynamic. Positive displacement pumps are operated by filling a cavity and then displacing a given volume of liquid. And also it delivers a constant volume of liquid for each cycle of functioning. It is then divided into two as rotary and the reciprocating. Then those can be sub divided as the structure above.

            And other main type is dynamic pumps. It is also called as roto-dynamic or centrifugal pump. Its function is happened by producing a head and flowing by increasing the velocity of the liquid through the pump with the help of rotating impeller. These types of pumps are included with radial, axial and mixed flow units.

When we compare those two types of pumps positive displacement pumps generally gives more pressure rather than centrifugal pumps. And also when we consider about the viscosity variation of a fluid and the flow of the pump, then centrifugal pump flow is reduced when the viscosity is increased. Then the positive displacement pump flow is increased when viscosity is increased. So when we select a pump we should consider about the viscosity of the fluid to get the maximum efficiency of the pump.

Classification according to the Power supply method

            In pump classification systems, pumps are also classified as their power supply method, because there are various types of power supple methods available for pumps. Reason for that is in various applications various power sources are available and some are not available. For an example in rural areas some time there is no electricity available so we have to move for another method. So in the industry they produce different type of power supply system according to the customer requirement.

            In industrial as well as domestic application we can observe different type of power supply systems as given bellow

·         Natural Power (Solar, Wind, Etc)

·         Electric Power

·         Fossil Fuel Power

·         Pneumatic Power

·         Mechanical System          

            In some industrial application in rural areas there are no such power are available. So in those areas we can apply natural power supply system such as solar power, wind power, and other natural resources. Those are environment friendly power sources because when we compare with other resources they have less air pollution (can be consider as no air pollution with respect to the others) and less sound pollution. And also natural power resources are economically viable with respect to the others.

            Electrically powered pumps are common in most of the applications. Most probably those are used in domestic applications. This also can be considered as environment friendly power resource but when we consider about the cost for the supplying power is high and also it is risky system for supplying power.

            One of the other common uses of pump type is fossil fuel powered pump. For that normally diesel power is used and also other fossil fuel pumps are rarely used. But these types of pumps are the most environment polluted pumps because it emits various types of unfair gases and also sound pollution is very high. So it is not environment friendly.

Pneumatically powered pumps are normally used in applications where the compress air is freely available such as in underground mine and also the places where the drill machines are used which powered by compress air. This type is also environment friendly except the sound pollution when use.

            Other type is mechanically powered pumps. Those are used normally in rural areas where the no more sources are available and also in small scale applications. In this system mechanical system is used for pumping. 

Classification according to the Transporting fluid type

            Pump classification also can be done according to the fluid which transport by using the pumps. Normally there are several types of pumps classified according to this type such as water pumps, sludge or slurry pumps, and others.

            So when we going to select a pump for our application we should consider about those types for receiving the maximum efficiency.

Pumps

Definition of a pump 

                       Generally a pump can be defined as an instrument or a device which can be used to transport the fluids. The fluid may be a liquid, slurry or a gas. As the fluid type the pump design and the method use for moving the fluid can be varied. (Michael W. Volk, Pump characteristics and applications, 01-05)

When we consider about a water or fluid controlling system, use of pumps is very effective method for it rather than control manually or mechanical system. Normally a pump is used to transport water from lower elevation to higher elevation. In the market there are various types of pumps are available as various requirements of the customers. And also there are pumps available as the various types of power supply methods. Pumps are used in various applications such as domestically as well as industrially.So we should consider various types of thing when we going to buy a pump.

Selecting a pump

         If we want to buy a pump for our application, we should select appropriate one as our requirement of the application. So we should think various types of factors depending on various situations. It can be listed as follows 

·      Amount of water body which have to be transported (Pumping rate)

·      Properties of the fluid (Density, viscosity, Solid content, Etc)

·      Type of flow (Laminar, Turbulent, Etc)

·      Pressure head variation (Suction, Discharge, Total)

·      Power supply (Electric, diesel, Pneumatic, Etc)

·      Cost compare to the efficiency

      One of the most important factors is pumping rate. It means the amount of fluid collected per unit time. So we need a pump which has a pumping rate more than the collecting rate. Or else we can’t remove the fluid effectively. In some cases we have limited time allocates for pumping so we have to pump within that limited time so we have to select a pump with that rate.

And also, when we going to select a pump, we should think about the properties of our transporting fluid such as density, viscosity, solid content, Etc. With the change of density of the fluid, power required for pumping is varied. And also the system of pumping is varied. So we should thin about the density of our fluid as well as the viscosity. And also the solid content of the fluid is very important to consider because the contaminant are caused to damages to the part of the pumps. So in those cases we have to select special types of pumps. So we should analyze the solid contaminant of the fluid. 

Another factor is the type of the flow of our fluid. It means the behavior of the fluid. It may be laminar, turbulent or another type. So we have to examine our flow type of the fluid because some pumps cannot be transport turbulent flowed fluids. So in that case we have to use special type of pump. 

 

And also the pressure head variation or the vertical height of the transportation of fluid is very essential when selecting a pump. So we should know the head of suction, discharge as well as total head. It is very important to select a pump and placing the pump (Paul N. Garay, Pump application desk book, 231-240). 

  

H1-Suction head

H2-Discharge head

(H1 + H2)-Total head 

                                     

            Power supplying method to the pump is also very important when we going to buy pumps because some powering methods cannot be used in every situation.  Now a day there are several method are used to supply the power to the pumps such as Electric, Diesel, Pneumatic and others So as our application we have to select appropriate method.

            Finally, we should thing about the cost we should spend for buying he pump. It’s depended on the scale of the application. For an example it is useless if we use a high cost pump for small scale application. So we should think about the cost with respect to the efficiency of the pump.