COLLECTION OF INFORMATION ABOUT PUMP SYSTEM 

The quality and reliability of initial information about the pumping system and operation modes define the final result and economic effect of the energy savings measures.

The first step in an audit of a pumping system is the answer to the question -  

"What pumping systems and pumps are the best candidates for the assessment?"

  1. Sort pump by driver size, annual operating hours, and estimated energy cost.

  2. Select pumps with power more than 30 kW.

  3. Pumps which have maximum operating hours.

  4. Pumping systems with throttle or bypass control must be considered at first.

  5. Focus on centrifugal pumps operating at a fixed speed.

  6. Pumps with low reliability, lowest MTBF (mean time between failures) and with great expenditures on service. These facts can be the evidence that the pump operates beyond the operating range and not caused by the low quality of a pump like many pump users can think.

  7. Pumping systems with extra vibration and noise (pumps, valves, pipes, etc). If a throttling control is used the source of noise is valves.

  8. Pumps with a long term of service. (old pumps have declined characteristics). Worn, eroded, corroded, distorted or broken impellers/diffusers/vanes or wear rings and casings. Increase clearance in wearing rings is the main reason of characteristics declining.

  9. Pumping systems with large flow or pressure variations. For example, water supply systems have very different demands during the day.

  10. Where the number of operating pumps is not adjusted in response to changing conditions.

  11. Systems with multiple pumps Multipump stations in which neither number of pumps nor their speed don't change.

  12. Cavitating pumps. It can be caused by clogged suction pipeline or clogged strainer.

  13. Pumps that operate beyond the operating range.

 
The information about pump
  1. Manufacturer of a pump. Model of a pump. Serial number.

  2. Date of manufacturing and term of operation at a site.

  3. Parameters of a pump - Flow, head, efficiency, power, speed, the number of stages. Pump performance curves. Design point (flowrate and head);

  4. The real and nominal diameter of an impeller. (Users can trim impeller to reduce pump flow and head. A lot of users do it by themself). 

  5. Maintenance records. Information about repairs and retrofitting (trimming of impellers, replacement of impellers and so on).

  6. Is it possible to measure pump parameters - inlet pressuer, outlet pressure, capacity?

 

Where to get information about pump installed on the site.

 

  1. The information in the documentation that was delivered with the pump. The documentation which was delivered with the pump is the most reliable source of information about the pump. The table on the pump.

  2. The performance curve can be got from the catalogs. But this way cannot be considered as a very reliable method because the pump could be made for not standard parameters (special trimming, special impeller and so on)  The real pump curve can radically differ from curve presented in catalogs because of wear. 

  3. To validate information about the pump and define the real condition of a pump It is necessary to do on-site tests.

The information about electric motor or drive

Nameplate information

 

  1. Line frequency

  2. Motor size (rated power)

  3. Motor rated speed;

  4. Motor rated voltage;

  5. Motor full load amps (FLA) - the current to the motor when operating at rated power;

  6. Motor power rating information;

  7. Nominal efficiency or efficiency class (if provided);

  8. Motor type and characteristics;

  9. Type of drive (e.g. variable frequency drive, belt, gear, direct);

  10. Motor history (e.g. original, rewound, replaced)

 
 Detailed information about a pumping system
  1. System layout.

  2. PID diagrams.

  3. Operation conditions.

  4. System curve. Static head in the overall head. Is it the pumping system with preliminary static head or friction losses? 

  5. Load profile. Does system curve change during the time? What are the maximum and minimum and the longest modes?

  6. Pump control method:

    - speed control of pumps;

    - throttle control (valve percentage open if available);

    - by-pass/recirculation;

    - on/off;

    - pumps in series or in parallel, or split duty;

    - not controlled (pumps just run)

 
Data collection tips

- Determine if data collected is a representative snapshot or if the system needs to be evaluated over a longer period of time or if historical process control data is available.

- Pressure measurements should be taken with calibrated, reliable gauges or transmitters.

- Flow measurements should be taken with properly installed, calibrated meters.

•If using portable flow meters, confirm measurement at alternative locations

•May use dP across a component and component curve

- Motor input power

•Preferably measure power directly with a power meter

 

- Cross-validation

•Flow rate, pressure, and power measurements may not be available but can be determined using cross-validation

•Use pump differential pressure (total head) and pump curve to estimate flow rate

•Use motor input power and efficiency to calculate shaft horsepower, then use pump curve to estimate flow rate

•Use valve position, flow rate, and Cv data to estimate dP

•Measure drawdown and fill times to estimate flow rate