Power Plant Guruji

What are Mechanical Seals for Pumps  The Sealing of a rotating shaft passing through a pump casing is also achieved by means of a rotating, optically flat seat, rubbing against a stationary, optically flat seat. Stationary seat is inserted into a gland plate or seal chamber and the spring loaded rotating face is mounted on the shaft. The spring holds the rotating face against the stationary face and sealing occurs in between rotating and stationary parallel faces. Also Read : Why use Mechanical seal in pump Gland seal vs. Mechanical seal Why priming centrifugal pumps How many types of mechanical seals are there  Shaft mounted or cartridge type Balanced and unbalanced type Pusher and non-pusher type Single and multiple seals  Externally and internally mounted seal Single and multiple spring seal  Mechanical Seal Types You May Also Like : What are the types of pump ? Coolant and lubricant Types of valve used in power plant Calculate suction head in centrifugal pump A variety  of seals ar

  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 questions Water tr

 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 ? Gland se

  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 types of

  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) +                                                                              - Static Suction head (Hs) - Pressure drop (Frictional head loss)(Hf) - Vapour pr

  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 accumulation of bubbles around a pump impeller is called cavitiation. S