A pump is a machine or device for raising, transferring, or compressing fluids. Pumps represent the largest single use of power in industry (31%) by motor driven equipment. Process variables, including pressure and flow of gases and liquids, have long been regulated using mechanical clutches, throttles, and adjustable inlet guide vanes. Pumps often operate as a variable torque load, a load that increases as the speed increases. These mechanisms waste energy, require frequent maintenance, and provide inaccurate control.

Pumps have two main categories:

1. Positive displacement pumps force a fixed volume of fluid from inlet to discharge with each stroke or rotation. (e.g., reciprocating, rotary, or screw type pumps)
2. Centrifugal pumps are the biggest class of pumps, which use the fluid's own momentum to build up pressure or head. Centrifugal pumps use centrifugal and hydrodynamic forces to create pressure that moves the fluid from inlet to discharge.

Pumps can also be classified by principle of operation and drive requirements.

• Principle of Operation Application Served
• Materials of Construction
• Liquid Being Pumped
• Shaft Orientation (Vertical, Horizontal)
• Number of Stages
• Suction Port Arrangement

• Reduce energy costs
  Motors use less energy as speed is reduced.
• Reduce demand charges
  Drives reduce motor starting current 8-10 times.
• Variable and constant torque load characteristics, depending on pump type.
• The motor may spin backwards due to pump backpressure when stopped.
• Control of pressure and flow is desired.
• High reliability.
• Wide horsepower range for different pump sizes.
• Environmentally friendly (harmonic standards).
• Network communications.
• Prevention of water hammer, pipe stress, valve, and pump seals and cavitation prevention.

Yaskawa AC drives provide an efficient, more maintenance-free, accurately controlled power source for pump systems. Yaskawa AC drives adjust impeller speeds to modify the pump curve. Use of an AC drive is preferred to valve control due to the benefits of efficiency. Yaskawa drives provide many benefits over traditional mechanically controlled methods. The benefits are both cost and performance related. Yaskawa AC drives reduce peak energy demands by capturing the speed of a pump that is running backwards due to backpressure. Using Yaskawa’s Bi-directional Start function causes a free wheeling pump to reverse and restart under controlled conditions unlike a line started pump motor. Energy Saving Mode reduces motor voltage during low demand conditions to save power. A PID controller built-in to the AC drive eliminates the initial cost of external PID controllers.

Speed Search is used to reduce stress on pump belts, pipes, and valve seals to reduce maintenance and replacement costs for the pump system. Yaskawa AC drives have integral communication options that help reduce the initial cost of separate network gateways. Torque detection can warn the user of pump cavitation or a clogged pump system before serious damage occurs.

Classification of Pumps by Operating Principle:

• Kinetic (Dynamic) Pumps

• Centrifugal Pumps
  Radial Flow
  Axial Flow
  Mixed Flow

• Regenerative Turbine
  Peripheral
  
• Jet Pumps

• Positive Displacement Pumps
  Reciprocating Pumps
  Piston
  Diaphragm
  Rotary Pumps
  Circumferential
  Screw

Additional Information
The pdf contains the same information as the web, but in some cases may contain more and should be used if a printed version is required.

• Open Drives Pump Application Overview (PDF Format, 165K)