The power consumed to overcome the static head in a pumping system varies linearly with flow, and little can be done to reduce the static component of the system requirement. But, several energy- and money-saving opportunities exist to reduce the power required to overcome the friction component of the pumping system.
The frictional power required is dependent on:
- Rate of flow.
- Pipe size (diameter).
- Overall pipe length.
- Pipe characteristics (surface roughness, material of construction,etc.).
- Properties of the liquid being pumped.
Figure 1 shows the annual water pumping cost (frictional power only) for 1,000' of pipe length for different pipe sizes and rates of flow.
One ExampleA look at a single example shows how optimum pipe sizing can reduce pumping costs.
Suggested Actions to Reduce Pumping Costs1. Compute annual and lifecycle cost for systems before making an engineering design decision.
2. In systems dominated by friction head, always evaluate pumping costs for a couple of different pipe sizes and try to accommodate pipe size with the lowest overall lifecycle cost.
3. Look for ways to reduce friction factor. If your application permits, the use of plastic or epoxy-coated steel pipes can reduce friction factor by more than 40%, proportionately reducing your pumping costs.
- Xenergy Inc., United States Motor Systems Market Opportunities
Assessment, prepared for the U.S. Department of Energy, December 1998.
- Mohinder K. Nayyar, Piping Handbook, McGraw-Hill Publications, New York, 1998.
- Hydraulic Institute, Engineering Data Book, Second Edition, New Jersey, 1990.
- Improving Pumping System Performance: A Sourcebook for Industry, Motor Challenge and Hydraulic Institute, January 1999.
- Pumping System Optimization, Training Workshop offered by the U.S. Department of Energy.