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  Why pumps are used in parallel and series mode ? Let us begin with the basics of centrifugal pump mode of operation. Mode of operation can be either Parallel mode and Series mode. Pumps can be arranged in parallel or serial mode to provide an additional head or flow rate capacity. Recommended for you : Why priming centrifugal pumps Calculate suction head in centrifugal pump What is parallel operation of pump ? To get constant head and additional flow pumps are arranged in parallel. Head (H) H1= H2=H3=H Constant Discharge (Q) = Sum of each Pump discharge = Q1+Q2+Q3  Parallel operation of pump Also Read : Why use Mechanical seal in pump Gland seal vs. Mechanical seal What is series operation of pump ? To get constant flow and additional head pumps are arranged in series. Discharge(Q) =Q1=Q2=Q3=Constant Head (H) = Sum of each pump head = H1+H2+H3  Series operation of pump You May Also Like : What are the types of pump ? Coolant and lubricant Boiler feed pump operation...

 What is Priming? The removal of air by filling the pump passages i.e, flow passages. eg. The impeller and the volute casing with liquid. Priming is the adding of water to the pump cavity so that enough suction can be created by the impeller to pull water. Priming in centrifugal pump  Why is Priming essential in a Centrifugal Pump? Centrifugal pump does not displace liquid positively. They cannot displace gases and Vapours. Removalof these gases, air bubbles and vapours is very essential and a must before starting any centrifugal Pump in order to extend the pump life. What are different methods of priming ? PRIMING METHODS With a flooded suction A bypass around the discharge check valve The foot valve with auxiliary liquid supply An ejector for priming A priming tank holding the supply of liquid Vacuum pumps (manually/automatically) controlled to prime the main pump Must read related posts Cavitation formation in pump Function of volute casing in pump Why use Mechanical seal ?...

  Starting procedure of Centrifugal Pump Check the cooling system and turn it on. Check the coolant flow Properly. Open the suction valve and close all the drains in the casing and piping. Prime the pump and ensure that there is sufficient liquid to feed the pump. Start the motor and let it come to the proper speed. When rated speed is reached then open the discharge valve slowly. Check the leakage in piping and stuffing box. Check all the parameters like pressure, temperature,flow, vibration Current etc. Bearing temperature should not exceed 65°C during   operation. In case of any Sound or pump shows Overheating of bearing, then the pump should be stopped. Stopping procedure of Centrifugal Pump Discharge valve should be closed first. Stop the pump motor. Close the suction valve. Close the bearing and gland cooling lines. Also read related posts Cavitation formation in pump Function of volute casing in pump Why use Mechanical seal ? Gland seal vs. Mechanical seal What are the ...

  Concept of NPSH in pump Net Positive Suction Head or NPSH represents the suction head at the pump impeller eye. It represents the head required to make the fluid flow from the suction pipe to pump impeller. For a smooth and cavitation free performance of the pump, NPSH Net Positive Suction Head must be positive and should have a value that the flowing fluid does not change under reduced pressure. Higher suction lift, higher temperature of the fluid, higher losses in pipelines, all these tend to reduce available NPSH Net Positive Suction Head. Pump designer give us the NPSHR (equired) usually depending upon the test results of the actual pump. It is necessary that the available NPSH must be higher or equal to NPSHR. NPSH calculation for suction lift Calculation of NPSHA (available NPSH) NPSHA = Pressure Acting on surface (Pa) +                                            ...

  What is  Cavitation? Derived from the Latin word 'Cavus', which means a cavity or a hollow space. Defined as the rapid formation and collapse of cavities in a flowing liquid in regions of very low pressure. If the pressure at any point inside pump particularly at the suction line, drops below the vapour pressure corresponding to the temperature of liquid, the liquid will vaporize and appear as cavities of vapour or vapour bubbles. These cavities are carried up stream along with the liquid until a region of high pressure formed inside the impeller, where the cavities collapse with a tremendous impact on the side walls of impeller vanes. This phenomenon is called cavitation. How does cavitation occur ? Cavitation occurs when a pump is under low pressure or high vacuum conditions,  it does not receive enough flow. When this happens, bubbles or cavities will form at the eye of the impeller. This formation and ...

  1.What deals power-system protection ? Ans. Power-system protection is a branch of electrical power engineering that deals  with the protection of electrical power systems. 2.A good electric power system should ensure that ? Ans. A good electric power system should ensure the availability of electrical power  without any interruption to every load connected to it. 3.Power protection systems limit ? Ans. Power protection systems limit the damage at the fault location and prevents  the effects of the fault spreading into the system. 4.What are the nature of faults ? Ans. The nature of fault simply implies any abnormal condition which causes a  reduction in the basic insulation strength between phase conductors, between  phase conductor and earth or any earth screen surrounding the conductors. 5.Voltage breakdown due to ? Ans. Voltage breakdown could be due to normal voltage or abnomal voltage. 6.Causes of faults could be due to ? Ans. Causes of faults could...

  Circuit Breaker A circuit breaker is a switching device that interrupts the abnormal or fault current. It is a mechanical device that disturbs the flow of high magnitude (fault) current and in addition performs the function of a switch. The circuit breaker is mainly designed for closing or opening of an electrical circuit, thus protects the electrical system from damage. Tripping and Auxiliary Supplies Trip Circuit A relay provides a potential free contact, which is shown in the figure as Trip Contact', at the time of fault sensed by the relay. The auxiliary supply goes through this contact to the Trip Coil of the circuit breaker. circuit breaker trip circuit Auxiliary Supply All the circuit breakers are DC (Direct Current) operated. Because DC power can be stored in battery and at the time of total failure of incoming power Occurs, still the circuit breakers can be operated for restoring the situation by this battery. Hence, the battery is another essential item of the powe...

  Function of volute casing in centrifugal pump? Functions of a pump volute: To convert kinetic energy impaired by the impeller into  pressure energy To minimize losses during this energy conversion process The pump casing does not take any part in dynamic head generation The best volutes are of constant velocity design Kinetic energy is converted into pressure energy only in the  diffusion nozzle immediately after the volute throat Various types of volute Single volute Double volute Vertical pump with diffuser Volute with diffuser vanes Circular volute Double Volute A double volute casing has two single volutes 180° apart Total throat area of two volute is same as the throat area of a comparable  single volute Double volute significantly reduces the radial load problem of the  single volute pump Hydraulic performance of a double volute pump is nearly the same as  that of a single volute Double volute pump is around 1-1.5 point less efficient at   B.E....

 Why Use Mechanical Seals ? 1. Lower Mechanical Losses Mechanical seals cause lesser mechanical losses compared to packed glands and thus makes the pump more efficient. Mechanical losses due to frictional drag of the shaft sleeve running against packing account for the largest of the mechanical losses generally incurred in a centrifugal pump. 2. Lesser Sleeve Wear For mechanical seal fitted pumps handling clean, non-corrosive liquids, shaft protecting sleeve can be eliminated. Even where shaft sleeves are used, they are not subject to wear for mechanical seal fitted pumps. In case of packed gland pumps the sleeve under the packing is subjected to wear especially when the pump liquid contains abrasive particles or when the packing sit fixed very tightly on the sleeve. Sleeve damage is costly not only because of the cost of sleeve but also due to the time involved in replacing the worn sleeve with a new one. 3. Seals high pressure as well as low pressure Increased pressure ...

  Voltage Transformer or Potential Transformer Voltage Transformers (VTS) - Importance Voltage transformers are the next  important component of Protection. Voltage Transformers: are used for measuring and protection may be single phase or three phase provide isolation from high voltages must operate in the linear region to prevent accuracy problems must be capable of driving the burden, specified by relay manufacturer Types of Voltage Transformers (VTS)  There are two basic types of VTs-Electromechanical VTs and Capacitor VTS. Electromechanical VTs Are similar to a power transformer May not be economical above 132kV Robust and more reliable Capacitor VTs Used at high voltages (132 Kv or above) Main difference is that CVT has a capacitor divider on the front end Require maintenance as capacitor is used