PUMPS AND DRIVERS NCCER 40108-07

2.0.0 Pump Types Pump – a mechanical device designed to increase the energy of a fluid so that a quantity of the fluid can be transported from one location to another. Operate under the general principle that fluid is drawn into one end (suction) and forced out the other end (discharge) at an increased velocity. Classified as: Centrifugal Positive-Displacement

2.1.0 Centrifugal Pumps Rotating impeller increases the velocity of the fluid.

2.1.1 Double-Suction Centrifugal Pumps Fluid is drawn in on both sides of the impeller. Used to pump large volumes of fluid.

2.1.2 Multi-Stage Centrifugal Pumps Each impeller (stage) increases the velocity. Stages are stacked until the desired pressure is reached.

2.1.3 Slurry Pumps Slurry – a mixture of different fluids, with large quantities of solid particles.

2.2.0 Rotary Pumps Positive-Displacement pumps that operate by a turning motion. Types include: Gear Screw Vane Flexible Impeller

2.2.1 Gear Pumps Fluid is drawn from the suction, around the outside of the teeth, and out the discharge. Spur gear is the most common rotary pump.

2.2.2 External Gear Pumps Fluid is drawn from the suction, around the outside of the teeth, and out the discharge. Can be operated in either direction.

2.2.3 Internal Gear Pump Have two gears that mesh together. Outer gear is the driving gear.

2.2.4 Helical Screw Gear Pump Pumping oil and heavy fluids.

2.2.5 Vane Pumps Pumps hydraulic oil, solvents, and chemicals. Vanes are made of soft material.

2.2.6 Flexible Impeller Pumps Rotary pumps used primarily for chemicals.

2.3.0 Reciprocating Pumps Operate by back-and-forth (or up-and-down) straight-line motion, incorporating a suction stroke and a discharge stroke. Suction stroke: Suction valve open; discharge valve closed. Discharge stroke: Suction valve closed; discharge valve open. Delivers a pulsating flow. To compensate for the pulsation, an air chamber is placed on the discharge line. Three main types: Piston Plunger Diaphragm

2.3.1 Piston Pumps Pumping element is a piston, which moves back and forth in the chamber. Piston is shorter than stroke length.

2.3.2 Plunger Pump Plunger moves fluid into and out of the cylinder. Plunger length is greater than stroke length.

2.3.3 Diaphragm Pumps Flexible diaphragm moves the fluid. Ideal for caustic chemicals. Also used for metering exact quantities.

2.4.0 Metering Pumps Due to close manufacturing tolerances, these can pump exact amounts of fluid. Very sensitive to temperature changes and abuse. Three types: Plunger metering pumps Diaphragm metering pumps Peristaltic pumps

2.4.1 Plunger Metering Pumps The most common type used in industry today.

2.4.2 Diaphragm Metering Pumps Uses a diaphragm to move the fluid.

2.4.3 Peristaltic Pumps Specialty pump for chemical applications. Uses two shoes on a rotor to squeeze fluid along a hose.

2.5.0 Vacuum Pumps Creates a vacuum (negative pressure) instead of a positive pressure. For double-suction vacuum pump (liquid-ring compressor): a liquid, usually water, is used to seal the rotor and cone clearance.

3.0.0 Net Positive Suction Head and Cavitation Net Positive Suction Head (NPSH) is the amount of suction head (pressure) required to prevent vaporization of the pumped liquid.

3.1.0 Cures for Cavitation Cavitation – formation of vapor bubbles due to the NSPH available is less than the NPSH required. At 72 F: 1 cf3 liquid water = 1,700 cf3 vapor water Reduce cavitation by reducing vapor pressure: Increase the static head: Lower the pump Raise the level in the tank Raise the tank Increase the pressure head: Pressurize the tank

3.2.0 Air or Vapor Blockage Sometimes, cavitation is not caused by NPSH. Air in system: Creates a severe lowering of NPSH and causes noise but not as destructive as cavitation. Sources of air entering the suction: Loose or worn packing is the most likely spot. Leaks in valves and fittings.

4.0.0 Installing Pumps Pump installation is a performance of precision. Suction and discharge lines must be plumb, level, and aligned. Pump must be aligned with equipment centerline. Drive motor must be precisely aligned with pump.

4.1.0 Pre-Installation Guidelines Baseplate: If you get the baseplate right, the remainder of the installation will be smoother. Aligned Level in all directions Correct elevation Clean grouted if applicable.

4.2.0 Installation Guidelines Drill/Tap holes as necessary Set pump Shim so that pump c-line is higher than motor Assure pump is plumb and level Align motor to pump Connect suction and discharge

5.0.0 Drivers Electric motors Internal combustion engines Turbine engines (extreme high speed/volume)

5.1.0 Identifying Types of Drivers Electric motors Constant or variable speed Internal combustion engines Reciprocating drivers Turbine engines extreme high speed

5.2.0 Electric Drivers

5.2.1 Variable Frequency Drivers Speed control is adjustable so that desired flows and pressures can be achieved precisely.

5.2.2 Motor Winding Field Windings: The number of turns of wire on the stator which determines the motor strength.

5.2.3 Power Optimization Electricity is expensive. Companies are always looking for ways to reduce electrical consumption.

5.3.0 Diesel Drivers Used where electricity is not available. Used during power outages for critical pumping requirements.

5.4.0 Gas Drivers Use unleaded gasoline, liquid petroleum, or natural gas.

5.5.0 Turbine Drivers Not as common as other drivers. Most are set up to turn a driveshaft, which turns more than one pump.