P22 PUMP EFFICIENCY AND FLOW METER

The Fundamentals
The Technology
The Benefits
Industry Sectors include
How does the P22 work?
P22P Portable Sytem
P22F Fixed Systems
Data display and derived information
Tapping points
P6000 Power Meter
Accuracy of Pump Efficiency measurement
The P22 thermodynamic flow meter
Quantifying the benefits
Advanced applications
Features and benefits include

The Fundamentals

Pumps use nearly 20% of the world's electrical energy.
Responsible for about 7% of the world's greenhouse gas emissions.
Energy and Maintenance typically comprise 90% of Life Cycle Costs.
Studies have shown that 20% or more of the energy consumed by pump systems could be saved through equipment or control changes.
Pumps are often critical components of a process. Plant reliability is optimal when they are maintained on the basis of regular or continuous condition monitoring.
Performance-based maintenance costs are significantly lower than calendar-based costs.
- If you don't measure it you can't manage it

The Technology

Thermodynamic Condition Monitoring with portable (P22P) or fixed (P22F) instrumentation provides the information required for management of energy, emissions, reliability, and maintenance.
Measures differences in the internal energy of fluids and gases, using temperature and pressure probes, and power meters.
Provides accurate measurements of energy efficiency, flow rate, and other key parameters for pumps and turbines.
Utilizes accurate and stable measurement of differential temperature, to better than 1/1000 degree Celsius (1 mK).

The Benefits

Reduced electricity and maintenance costs
Lower greenhouse gas emissions
Improved plant reliability
Save money AND help save the world from global warming

Industry Sectors include

Water and Wastewater
Petrochemical
Mining
Pulp and Paper

Irrigation
Hydroelectric
Power generation
Steel

Sustainable development
Plant reliability and process improvement
Energy usage
Operations and maintenance
Environmental
Health and safety
Pump test and maintenance specialists
Research and educational establishments specialising in hydraulic efficiency measurements

In the thermodynamic method, pump or turbine efficiency is measured by means of temperature and pressure probes fitted to tapping points on the pump's inlet and outlet. Flow rate is derived from the pump efficiency measurement and the electrical power supplied to the pump.

Pump (or turbine) efficiency is accurately measured by innovative and stable temperature and pressure probes

Flow is accurately derived from efficiency and power input

The critical parameter is the differential temperature across the pump, which must be measured to an accuracy of typically 1mK. This is especially important for fixed installations and is achieved with Robertson Technology's CoolTip™ technology, now incorporated into the P22 to provide accurate, stable, and cost-effective measurement of pump efficiency and flow.

P22P Portable Sytem

Portable units are used for investigative work and regular monitoring.

Standard Configuration of P22P Portable

Testing 2 * 1MW pumps in series, simultaneously, with 3 sets of battery-powered probes, and wireless connections

Probes at one tapping point, with battery and wireless connection

Control and analysis computer, with wireless link

P6000 power meter with wireless link

P22F Fixed Systems

Fixed installations provide on-line predictive monitoring of critical and high power pumps, giving early warning of pumping problems and reduced risk of plant failure. They can be interfaced with pump scheduling software, which selects pump combinations to achieve the pumping requirement with lowest electricity costs. Fixed units were not a viable option prior to the development of CoolTip™ technology, as they require very stable differential temperature measurement over long time periods.

Standard Configuration for P22F Fixed Unit

P22F fixed installation for continuous monitoring, with pump scheduling

(7 pumps, each 1 to 3 MW)

Panel-mounted power meters

Probes fitted to one pump

Control room

Data display and derived information

Data Display

The standard data acquisition window for each pump is shown. T1 is the inlet probe temperature (ºC), T2 is the outlet probe temperature (ºC) and dT is the differential temperature (ºC).

P1 is the inlet pressure (bar gauge), P2 is the outlet pressure (bar gauge), and dP is the differential pressure (bar).

H is the pump total head in metres of water, vH is the velocity head in metres of water, n is the pump efficiency (in %), On is the Overall Efficiency (in %), q is the volume flow rate in l/s, and pw is the electrical input power to the motor, in kilowatts.

Software versions can be supplied with data displayed in other units.

The most recently collected data is shown in the left-hand column. In the example, data for the 52nd sample in Data set 2 (a Data Set of 60 readings, taken at 1 second intervals), is displayed.

At the conclusion of the data set, averages, maximum and minimum readings, and standard deviations (StDev) are calculated and displayed, in the right-side columns. In the example, the information for Data Set 1 is shown. Note in particular the low standard deviation, 0.00068°C (0.68 mK), of the differential temperature.

Data sets can be run continuously, or there can be a dwell time between data sets.

From the measurements provided, graphs of pump parameters can be plotted, and compared with manufacturer's data to illustrate any changes in pump performance.

Tapping points

Temperature and pressure probe fitted to a tapping point via a gate valve and T-piece

15 mm (½ inch NPT/ BSPT / ISO) tapping points are required on the inlet and outlet of each pump to be tested, fitted with gate valves to allow insertion of 9.53 mm (3/8 inch) diameter temperature probes or thermowells. Thinner temperature probes, 6 mm in diameter, have been developed for use with thermowells. They can also be used with 3/8 inch NPT/ BSPT / ISO Tee-pieces and tapping points, which are sometimes already fitted to the pipe work. The 9.53 mm and 6 mm diameter probes can be inserted when the pump is running, up to a maximum pressure of about 15 bar (153 m of water) or 30 bar (306 m of water) respectively. Probes can be used at higher pressures if they are inserted with the pump not running.

The above configuration is suitable for 'cold-fluid' applications (0 - 60 ºC). Other arrangements may need to be made for higher temperature fluids, for safety reasons. For fixed units, it may sometimes be necessary to have separate tapping points for temperature and pressure probes, in particular for high temperature and pressure applications, and for corrosive fluids. In these situations, the temperature probes are inserted via thermowells.

Tapping points should ideally be about two pipe diameters from the pump flanges, but one pipe diameter is sufficient if space is tight.

P6000 Power Meter

The P6000 power meter was developed to interface with the P22 Pump Monitor, for the measurement of flow rate by the thermodynamic technique. It communicates kW to the P22 via an RS485 serial interface, with Modbus™ protocol. The maximum current input is 6A, and the maximum voltage input is 600V.

The current range is extended by means of three 1000:1 clip-on current transformers (CT's), capable of measuring currents up to 1000A.

Four clip-on voltage probes are supplied. Potential transformers (PT's) must be used for voltages higher than 600V.

Standard cables supplied are 3 m long.

The standard display is W, VAR, VA. Other parameters, such as 3*V, 3*A, and PF can easily be selected.

CT and PT ratios can be entered into the meter.

Accuracy of Pump Efficiency measurement

The more accurately the pump efficiency can be measured, the more accurate is the determination of potential energy savings, and payback periods for remedial work or pump replacement. With the P22, the accuracy of the pump efficiency measurement is typically +/-1%.

The temperature rise across a pump increases with head, so the higher the head, the more accurate the efficiency and flow rate measurements. Similarly, the temperature rise is higher for less efficient pumps, as more energy is being lost in the pump, so the lower the pump efficiency, the more accurate are the measurements.

Following international standards, we define accuracy in terms of Uncertainty, at the 95% confidence level. Thus, if the efficiency is 70%, with an uncertainty of 1%, there is a 95% probability that the pump efficiency lies between 69 and 71%.

For the P22, the uncertainty in pump efficiency in typical field conditions is shown in the table below, for a range of pump heads and efficiencies.

Typical accuracy of pump efficiency measurements under field conditions

The P22 thermodynamic flow meter

Thermodynamic flow meters have no moving parts, and their calibration can be checked on-site, over the operating range, by use of portable temperature, pressure, and power meter calibrators. Every pump has an individual flow meter, integral with the pump. There are minimal requirements for straight lengths of pipe work before and after the pump. Accuracy improves for higher head pumps.

For the P22, the uncertainty in flow rate in typical field conditions is shown in the table below, for a range of pump heads and efficiencies. This data excludes the error in any current or potential transformers used for the power measurement, and errors in motor efficiency.

Typical accuracy of flow rate measurements under field conditions

Quantifying the benefits

REDUCED ELECTRICITY COSTS. Save 10 to 15% by timely pump replacement or remedial work resulting from accurate performance-based pump tests. Save 20% or more with equipment or control system analysis and changes
PUMP SCHEDULING (fixed installations in high power pumping stations). Select combinations of the most efficient pumps for high tariff periods, based on continuous pump performance monitoring and specialist software. Save typically 3% of electricity costs.
REDUCED GREENHOUSE GAS EMISSIONS (in proportion to electricity used). Minimize energy taxes or penalties (vary with country and state)
LOWER MAINTENANCE COSTS. Studies show that performance-based maintenance provides typically 50% savings, compared with time-based maintenance
PRODUCTIVITY. Early indications of pump problems. Avoid catastrophic pump failure.
ELECTRICITY COSTS based on US$0.07 per kWh

Electricity Costs

Advanced applications

The following applications may require accessories, or non-standard hardware and/or software. Contact us for additional information

Wet-well pumps
Pump scheduling software
Pumps with negative suction pressures
Testing or monitoring two water pumps in series, simultaneously
Testing or monitoring two or more pumps in parallel, simultaneously
Sewage pumps
Fluids other than water, and slurries
Measuring the relative efficiency and flow rate of pumps in a bank of pumps in parallel, for fluids other than water, and slurries
High temperature and pressure applications
Interfacing data from existing power meters
Interfacing data from existing pressure probes
Detecting pump blockages
High voltage pumps (>600V)
Turbines

Features and benefits include

Low Cost
- 12 month ROI usually achievable
Thermodynamic technique
- International Standards apply
- More accurate than conventional method
- Simple to operate, and maintain
Accurate measurement of pump efficiency
- Reliable calculation of payback periods for remedial work
Flow measurement capability
- Measure both efficiency and flow to optimise overall plant performance without the need for separate flow meters (which can be difficult)
Optimises maintenance scheduling
- Early warning of poor pump performance
- Prevents unnecessary pump maintenance
Energy and environmental savings
- Reduce both electricity costs and associated greenhouse gas emissions
Improved process and plant reliability
- Continuous monitoring by fixed units provides early warning of pumping problems and reduced risk of plant failure.
Portable Instruments
- For investigative work and regular monitoring
Fixed installations
- For on-line predictive monitoring of critical pumps
Accurate and stable temperature and pressure probes
- CoolTip™ technology
Industry standard RS485 communication
- Simple and reliable operation
- Allows integration with vibration and bearing monitoring for complete condition monitoring
A technology for Sustainable Development