Post on 10-Sep-2020
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Specialized Hydraulics for Water Loss Management:Hydraulic Transients & Flow Measurements at Pumps
Fabian Papa | f.papa@hydratek.com | Ext. 410
Djordje Radulj | d.radulj@hydratek.com | Ext. 480
Toronto, Ontario | Tel: +1 416-238-7681 | www.hydratek.com
Significant hydraulic transients occur when there are substantial changes in the momentum of the water travelling in a pipeline which can occur for a variety of reasons including:
sudden break of a pipeline or component thereof;
sudden pump stoppages as typically occur with a power failure;
sudden valve closures;
rapid withdrawals from the system;
any other occurrence that changes the velocity of water travelling in a pipeline; and
any combination of the above.
Hydraulic TransientsIn most water systems, transient flow is the rule, and steady state is the exception…
Pump starts & stops
Pump Start Pump Stop
Negative Pressures
Magnitude & Frequency
Making changes to one part of the system affects other parts…always.
Pressure Reducing Valve (PRV) Adjustment → Change in Pumping Station Behaviour
Hydrant Operations
30 psi
Transients and Leakage
Leaks are …. Good for transients
Bad for efficiency
Without good transient control and proactive maintenance programs, we are chasing our own tail
Transient Pressure Monitoring
A transient pressure monitor consists of a: high frequency pressure transducer, smart data logger, and a host of additional equipment depending on the nature and complexity
Consists of the installing one or more transientpressure monitors in the field
Controlling Transients
Hydropneumatic tanks
Air is used to absorb transient pressure surges
Variable FrequencyDrives (VFDs)
Examples from Mexico of pump operations with and without VFDs
Controlling Transients
Air Valves
Surge Relief Valves
Pressure Reducing Valves (PRVs)
Controlling Transients
Maintenance Important!
Sample monitoring data
PRVs in Practice
Upstream of PRV
Downstream of PRV
40 psi drop
<10 psi drop
TransientUnnoticed…
Pump TestingMeasuring Flows Without a Flow Meter…
Thermodynamic Pump Testing Method
Thermodynamic Method
Measure Power (P)
Measure TDH (H)
Estimate hD and hM
Measure Temperature Gain DIRECT MEASUREMENT OF
Pump Efficiency hP
Calculate Flow (Q)
PMD
HQP
hhh
Measured
Wasted Energy Converted Largely to Heat Energy(Temperature Probes Capable of Measuring Accurately to 10-3 K)
TemperatureProbe
PressureGauge
Flow Measurement& Meter Verification
Example 2:Station meter over-registering flow
Implications: • Calculated NRW higher than it
really is, so…• Utility looked for leaks that
didn’t really exist
Example 1:Good correlation between station meter and thermodynamic method
Major Billing Meter Error
!
CFD Analysis
8 Pumps Mixer
Butterfly Valve
Differential Pressure Flow Meter
Results
Hydrodynamics at meter important!
Influenced by:
Pumps in operation and their locations
Appurtenances
Replace differential pressure flow meter with magnetic flow meter
Add flow straightener
Construction planned
The FixMagmeter
Flow Straightener
Other advantages ofThermodynamic Pump Testing
Of particular importance to water loss professionals:
Individual pump flow metering
Accurate hydraulic modelling
Energy reduction & optimization
Etc.Overall
Efficiency Gap
Efficiency Loss
Manufacturer’s Best Efficiency Point
Tested Best Efficiency
Point
Typical Operating
Point
Excellent Agreement Problem…
You cannot manage what
you don’t measure.
Specialized Hydraulics for Water Loss Management:Hydraulic Transients & Flow Measurements at Pumps
Fabian Papa | f.papa@hydratek.com | Ext. 410
Djordje Radulj | d.radulj@hydratek.com | Ext. 480
Toronto, Ontario | Tel: +1 416-238-7681 | www.hydratek.com
Questions?