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Home My WebLink AboutDDW-2024-012353Pumps & Motors Pre-certification Archimedes Pump First invented by Archimedes of Syracuse (287 BC – 212 BC) Called the Egyptian Screw Used to pull water from the Nile River to irrigate the Nile Delta. Human Heart Pump Classes Centrifugal is most commonly used & is a velocity type pump Positive displacement Frame Mounted Pumps Are a horizontal pump Pump and Motor bearings are independent of each other Motor can be replaced without removing pump piping Close Coupled Pumps Are a horizontal pump Impellers are supported by the motor bearings Piping in most cases needs to be removed to access impeller Vertical Lineshaft Pumps Lineshaft Turbine Can Turbine Submersible Axial Flow Lineshaft Turbine- Water Lube Lineshaft Turbine- Oil Lube Can Turbine Operates in flooded suction or pressure condition Submersible Axial Pumps Bowls Impellers Located in Bowls Multi-stage – bowls add pressure not volume Flow is restricted to the size of the bowl Diffuser Vanes Diffuser vanes convert velocity to pressure STUFFING BOX Packing or mechanical seal Packing glands Seal water - 5 psi higher than maximum suction pressure Lantern ring Seal Water External Seal Water Clean water source Used when pumped water has grit in it Needs to be turned on several minutes before starting pump Should have backflow preventer on clean water source. Impellers Vertical Pump Location Impellers Horizontal Position Impellers 3 types - open, semi-open, & closed Heart of the pump Made from metal, plastic, rubber Impeller eye - low pressure zone Suction of water is created at the center of the impeller, then it is pushed away from impeller by centrifugal force Open Impellers Semi-Open Impeller Closed Impeller Pump Rotation Volute Case Houses the impeller Curved vanes inside volute case are called volutes & convert velocity energy to pressure energy. Should be primed full of water on start up Wear Rings Keep water from recirculating from the high pressure zone to the low pressure zone Used to protect the volute case and impeller from wear Worn rings cause recirculation of water costing more to operate Wear Ring Worn out wear ring Split Case Pump Wear Rings act as a restriction between the impeller discharge and suction areas. LANTERN RING H - shaped cross section Made of metal or plastic Located inside the stuffing box where seal water enters Not used with a mechanical seal Allows water to flow evenly through the packing Seal Water SHAFT Driven by motor to turn & support the impeller Shaft sleeve - pressed on the shaft, located inside stuffing box Shaft sleeve is an expendable part used for wear SHAFT MACHINED SHAFT SLEEVE No Shaft Sleeve Worn shaft that had no sleeve Worn Shaft Sleeves CENTRIFUGAL PUMP COMPONENTS BEARINGS Anti-friction bearings * Roller bearings * Ball bearings Manufacturer determines type & frequency of lubrication Sleeve bearings Proper Bearing Lubrication Remove plug in grease relief port Press new grease into grease fitting displacing old grease Allow motor to run and let excess grease exit Replace plug in grease relief port BALL BEARINGS Outer Ring Inner Ring Cage Rolling Element ROLLER BEARINGS Supports radial loads and/or thrust loads depending on the design and where the rolling elements are placed ROLLER TYPE BEARINGS Needle BearingsRoller Bearings Sleeve Bearings Located in Spider SHAFT SEALS Packing Mechanical seals Separate the wet from dry end of the pump Mechanical seals are for high suction head, metal packing can also be used PACKING Should be adjusted to allow a steady drip of water from the packing gland Made out of braided animal, flax, plant, mineral or synthetic material Impregnated with some type of lubricant Comes in contact with shaft sleeve PACKING CONDITIONS Less than 100 psi or 1000 FPM 100 to 150 psi or 1000 to 2000 FPM Above 150 psi or 2000 FPM Plant fibers lubed with Teflon, silicon, TFE, or PTFE Graphite, acrylics, TFE, kevlar, PTFE, & carbons Metal, packing with metal cores or combination of synthetics & metals. Asbestos no long used CONDITIONS PACKING Stuffing Box Packing Location PACKING PROCEDURE Remove old packing, never stack new on top of old Cut in scarf or butt cuts Cut 1/16 - 1/8 shorter than shaft circumference Lubricate 1st ring & seat at the bottom of the stuffing box Stagger rings 90 degrees Line lantern ring with seal water Finger tight adjustment nuts MECHANICAL SEALS Located inside stuffing box Two surfaces: one is stationary and the other is rotating Stationary surface is made of a harder material than the rotating surface Spring keeps tension on the surfaces Seal components must match properly START-UP Rotate shaft by hand Run seal water 15 min. prior to start up Finger tight adjusting nuts Start pump, run 15 min., don’t adjust Adjust nuts equally, 1/6 turn every 15 min., until desired leakage is reached Stuffing box should be cool START-UP Check valve positions If pump has set for an extended period of time, the shaft should be turned to oil the bearings Check oil levels, amp readings, volt readings, flows, well info., Comments SLINGER RING Made of either leather or rubber Fits on shaft near the motor Prevents water from entering the motor bearings COUPLINGS Connect shafts of different diameters Transfer energy Most allow for slight misalignment Absorb starting torque Dampen vibrations Insulate units from electrical current Allow for end movement of shafts ALIGNMENT TECHNIQUES Straight edge and feeler gauge Dial indicator Severe vibration upon pump start up would indicate misalignment between motor and pump shafts PUMP MAINTENANCE Oil Drip rate = 5 drops per minute Use approved food grade mineral oil If a pump has been pulled for repair, you must have satisfactory bac-t results before putting back in service Pump Station Flow Each pump must be able to deliver the maximum flow of the station Make sure the shaft bearings are wet before starting the pump Flow increases with decreased pressure head Alternating pump operation will help keep windings dry & serviceable Booster pumps fill tanks & supply pressure to mains PUMP WEAR AND TEAR Pumps condition can be checked by comparing performance when new Wear is the main cause of loss in pumping efficiency Pump will run longer because of wear, increasing power costs Particles from wear can be seen in cooling water from stuffing box PIPING Eccentric reducer - suction side Concentric increaser - discharge side Eccentric installed with the flat side up, reduces air entering casing & one size larger than suction inlet Concentric increases pipe one size, reducing velocity and head loss, for higher pump efficiency Should be drained in freezing conditions & when the pump is shut down for long periods of time REDUCERS & INCREASERS VALVING A check valve prevents the shaft from spinning backwards and causing damage to the pump If no check valve, you can start and stop a pump with the discharge valve closed to prevent water hammer by opening it slowly CHECK VALVES Swing Check Valve Silent Check Valve Keep pump from spinning backwards Pump Control Valves Foot Valves Located at the bottom of suction pipe to hold prime Air Vacuum Release Valves Air vacuum release valves - prevent vacuum conditions during shut down, they also release air pockets during start- up. Placed at high points of the system RATCHETING DEVICES Motor Maintenance Follow manufacturer’s recommendations Over greasing - grease acts like an insulator, holding in heat, causing premature bearing failure Two most common speeds are 1800 and 3600 rpm Oil seals hold in the lubricant Pump Motor Operation Motor could overheat with low head pressure In a low pressure head situation, throttling the discharge valve would cool the motor cool down due to the increase of pressure head Losing a phase on a 3-phase motor would cause the motor to single phase and heat up. Voltage imbalance can cause the motor to overheat & burn out windings Blow dust off to clean motor housing Brake HP is HP supplied by the motor Vertical Motors Cutaway Motor Cutaway Motor Types Hollow Shaft Motor Motor With Shaft TROUBLESHOOTING Losing a phase on a 3-phase pump: *motor would continue to run *motor would overheat *damage could occur Cavitation Main cause of losing pump suction Sounds like pumping rocks or pinging Vibration & popping noises caused by low pressure in volute Generally caused by vapor bubbles Vapor bubbles implode causing damage to pump Volute case needs to be full of water Prevented by having adequate suction pressure and proper bowl depths Types of Cavitation Vaporization of the liquid in volute The "vane passing syndrome" from too small an impeller Too high suction speed Air ingestion on the suction side of the pump Turbulence of the fluid Priming a Pump Priming displaces the air in the volute case Helps the pump create suction so the pump will pump It also helps reduce cavitation TROUBLESHOOTING Bearing failure is first detected by a change in operating sound of the pump and vibration Accurate Record Keeping Shows loss of pumping efficiency along with record of flows & pressures Shows drawdown levels to evaluate condition of the well Drawdown level is elevation difference between static & pumping levels Helps determine proper depths for bowls. Shows when preventive maintenance or repairs were last performed Well Seals Well casing maintains an open hole for the well Sanitary seal - all openings around well head are sealed off to prevent contamination. Well Casing Well casing perforations provide a way for water to enter pump Well casing helps protect the quality of the water. Surging a well form of plunging or cleaning the gravel pack around the screen WELLS Well casing size is determined by the amount of water that is safe to yield Acidizing a well is a process used to rehabilitate a well for higher flows When a well pump is not running, the level of the water is the static level After a well pump runs for a period of time, the level is known as the pumping level Pressure Head Pressure at which a pump operates against expressed as feet of head or head feet Total static= static discharge head - the static suction head Static suction head is the height of the water above the suction inlet & is the pressure created by elevation or depth When calculating total dynamic head, static discharge head is part of the equation. The total operating head is the vertical distance of pumped water along with all other head losses Pump Curves Generally show capacity (flow rate), total head, power (brake horsepower), and efficiency The pressure at which a pump operates against is head pressure PUMP CURVES The pressure at which a pump operates against is head pressure Flooded & Lift Suction lift is the water level on the inlet side of the pump that is lower than the pump Suction lift should be limited to 15 feet Flooded means the pump has either an elevation of head feet or water system pressure to operate with Hydraulic Gradient END MEASURE OF PRESSURE USED DOWNWARD SLOPE MEANS PRESSURE IS USED UPUPWARD SLOPE MEANS PRESSURE IS ADDED MEASURE OF PRESSURE ADDED PUMP ON DOWNWARD SLOPE MEANS PRESSURE IS USED UP MEASURE OF PRESSURE USED FLOW START TANK GRADELINES FLOW FLOW PRESSURE HEAD HYDRAULIC GRADELINE PRESSURE HEAD HYDRAULIC GRADELINE RESERVOIR EMPTYING RESERVOIR FILLING HYDROPNEUMATIC TANKS Operate by applying air pressure to tank Tank levels controlled by pressure switches to pumps Air leaks can cause pumps to cycle on and off 1/3 to 2/3 air to water ratio limiting storage capacity Positive Displacement Pumps Positive Displacement Suction and discharge valves must be open all the way Used mainly for chemical dosing Not velocity-type pumps Peristaltic Pumps PISTON PUMP Bilge Pump Diaphragm Pump Double Diaphragm Pump Screw Pump Progressive Cavity Rotary Lobe Pump