Appendix C Master meter verification

Transcription

Comox Valley Regional District
Leak Detection Study – Comox Lake Supply
Final Report - Master Meter Verification &
600mm Hyprescon Line Comparative Flow Test
1400
1200
m3/hr
1000
800
600
400
200
0
Accuracy Curve
Accuracy %
30
10
-10 0
1
2
3
-30
Secondary Verification_P1/P4…
ABB Accuray Curve
-50
Velocity (m/s)
Flow rate (m3/hr)
50
1800
1600
1400
1200
1000
800
600
400
200
0
-200
Master West Flow
P1/P4 extended
East Meter SCADA
Dingwall PS
Time (hr:min)
July 2014
SUBMITTED BY:
10
8
6
4
2
0
-2
-4
-6
-8
-10
Meter Accuracy %
Master East Flow
Leakage Detection Study
Master Meter Verification & Comparative Flow Test
TABLE OF CONTENTS
1
EXECUTIVE SUMMARY .......................................................................................................4
1.1
Findings................................................................................................................... 5
2
INTRODUCTION ................................................................................................................6
3
MASTER METER VERIFICATION ............................................................................................7
3.1
3.2
3.3
3.4
East Master Meter .................................................................................................. 8
West Master Meter ................................................................................................. 9
Circulation Discovered Through Master Meters .....................................................10
Dingwall Pump Station Meter Verification..............................................................11
4
COMPARATIVE FLOW TEST - LEAKAGE MEASUREMENT - HYPRESCON LINE ......................................12
5
PRESSURE TRANSIENT LOGGING .........................................................................................13
6
SUMMARY OF RESULTS ....................................................................................................15
6.1
6.2
6.3
Meter Accuracy Verifications..................................................................................15
Hyprescon Leakage.................................................................................................15
Master Meter Circulation .......................................................................................15
TABLE OF FIGURES
Figure 1 – High Level Work Plan............................................................................................. 4
GLOSSARY OF TERMS
MNF
Minimum Night Flow
MUT
Meter Under Test
NFA
Night Flow Analysis
PZ
Pressure Zone
PS
Pump Station
Page 2
July 2014
Document Control
Version
Date
Authored by
Graham Waley C.Eng.
Manager, Veritec Consulting Inc.
2.1
01/11/2013
Approved
for Issue by
Alain Lalonde P.Eng.
Principal, Veritec Consulting Inc.
Mike Herschmiller
Circulation
list
Page 3
Manager of Water Services, Comox
Valley Regional District
July 2014
1
EXECUTIVE SUMMARY
Veritec Consulting was selected by the CVRD in 2013 to undertake a Leak Detection Study.
The diagram below lays out the high level steps which the project will undertake. The
Master Meter Verification and Comparative Flow Test presented in this report closes out
Step 2 of the finalized project scope. Although meter verification is not a standard method
for pinpointing leakage on distribution systems it holds much weight when assessing
transmission systems as the cost and practicalities of getting access to the transmission
mains is so restricted.
Step1: Measure Water
Loss Levels
Step2: Target Some
Higher Water Loss Areas
Step3: Deliver Water
Loss Benchmarking for
each Jurisdiction
Figure 1 – High Level Work Plan
After completing an initial system wide Night Flow Analysis 1 and then Water Audits for each
jurisdiction2 it was agreed to pursue the following activities;
 Verification of the chlorination station Master Meters.
 Comparative Flow Test down the Hyprescon transmission line.
The Water Audit had highlighted issues with the CVRD transmission system water balance as
in some months more water was sold on than was supplied into the system. The first Night
Flow Analysis session in May 2013 revealed apparent unaccounted for flow down the
Hyprescon line. Further investigative work was therefore planned to chase this unaccounted
for water.
An added value item for pressure transient logging on the transmission system is also
included. A fast pressure logger was deployed onto a fitting on the Master West header.
The fast logger records up to 8 times per second and hence can reveal the true extent of
surges on the transmission line which the existing pressure transducers reporting to SCADA
would not have the resolution to reveal.
1
Night Flow Analysis 08_05_13 CVRD Technical Memo v1.0 ISSUED
2
CVRD IWA Water Audit_2012 v1.0 ISSUED
Page 4
July 2014
1.1
Findings
The Meter Verification based on instantaneous flows only had the following findings;
 Master Meter East – Passed Accuracy Test.
 Master Meter West – Passed Accuracy Test.
 Dingwall P.S. – Passed Accuracy Test.
 Under-registration of Water Supplied to the CVRD Transmission System is not
originating at the Master Meters or Dingwall P.S. meter. The other significant bulk
meters left under suspicion are;
o Ryan Rd P.S.
o Courtenay #1
o Comox #1
o Comox #2
Zero Leakage has been confirmed on Hyprescon line.
Page 5
July 2014
2
INTRODUCTION
After completing an initial system wide Night Flow Analysis3 and then Water Audits for each
jurisdiction4 it was agreed to pursue the following activities;
 Verification of the chlorination station Master Meters.
 Comparative Flow Test down the Hyprescon transmission line.
The Water Audit had highlighted issues with the CVRD transmission system water balance as
in some months more water was sold on than was supplied into the system. This put
suspicion onto the meters. Selling more water than you draw means an under-registration
of the water supplied to that sector. An under-registration can either be driven by underregistration of import meters or over-registration of export meters. As the Master Meters
(MM) pass the most volume, and there is not budget to test a large number of meters, the
MM were the natural place to start verifications.
The major meters (>5% of water supplied to sector) involved in the CVRD Transmission
System are;
1) Master East
2) Master West
3) Dingwall P.S.
4) Ryan Rd P.S.
5) Courtenay #1
6) Comox #2
7) Comox #1
The NFA revealed apparent unaccounted for flow down the Hyprescon line. Meetings with
Courtenay and Comox revealed a low level of buy-in for field work such as pro-active leak
detection by Veritec in their jurisdiction under this project. With the CVRD LSA distribution
system receiving an ILI of 1.08 (close to minimum achievable - no recoverable leakage) from
the water balance, this left only the CVRD Transmission system and its unaccounted for
water to investigate for leak locations. It is worth noting that the CVRD water balance has a
high level of confidence due to all customer services being metered.
3
Night Flow Analysis 08_05_13 CVRD Technical Memo v1.0 ISSUED
4
CVRD IWA Water Audit_2012 v1.0 ISSUED
Page 6
July 2014
3
MASTER METER VERIFICATION
The method deployed for meter verification was to set up a secondary temporary ultrasonic
time transit flow meter at approximately the same location as the Meter Under Test (MUT).
The East Master Meter was a perfect location for such an installation. The West Master
Meter was much more constrained in terms of available space, pipework configuration and
appurtenances close to the existing mag meter. It was still possible however to install the
ultrasonic meter on the west header.
Efforts were made to capture a wide range of flows across the normal operating range of
each MUT in order to provide the most comprehensive meter verification possible. The
secondary meter was left on the East Header over-night. The East Header leads the West
Header flowing at approximately twice the flow rate.
The following pages summarize the data collected during the verifications. Data points are
plotted against the manufacturers factory accuracy curves. The accuracy of the secondary
meter is not absolute. As such error bands have been included around the secondary
meters flow profile. The MUT’s flow profile needs to fall within the secondary meters error
bands in order for the MUT to be deemed accurate and pass within the limitations of this
meter verification method.
To pass - The MUT’s average accuracy, referencing the secondary meter, must be within the
uncertainty assigned to the secondary meter. 1 minute flow data was used for the analysis.
The verification methodology has not interrogated totalizers for their accuracy yet. Checks
so far only performed for meter reporting accuracy on instantaneous flows.
Page 7
July 2014
3.1
East Master Meter
Uncertainty % = Path
variance = ± 2%
Page 8
July 2014
3.2
West Master Meter
variance = ± 4%
Page 9
July 2014
3.3
Circulation Discovered Through Master Meters
During the work to verify the Master Meters circulation was discovered. It was first visible as a +ve flow through the East Master Meter. The
West Meter is not set up to pick up reverse flows but our ultrasonics picked it up as can be seen in the top right graph in the previous section.
The East header leads the West header, due to its larger diameter and lower head loss, so there is a bias in place which is a good candidate for
initiating the circulation. By itself the circulation should not occur for much duration, however it does. After 20-120 mins the East Master Mag
stops picking it up (see green highlights below) but our ultrasonic meters which was in place in the East side overnight did. It seems likely that
the chlorine injection is providing the energy to perpetuate the circulation for several hours at a time.
With the circulating flow of 50 m3/hr being missed on the East header, and under recording of the reverse component on the West the net
effect is cancelled out. This is true except for the periods where the East MM is picking up the circulation (highlighted in orange below).
Comox East Flow Rate Comparison
1600
1400
Flow rate (m3/hr)
1200
1000
P1/P4 extended
800
East Meter SCADA
Errors on E&W
cancel out
Error being accrued
600
400
200
0
8:24 PM
9:36 PM
10:48 PM
12:00 AM
Page 10
Time
(mm:ss)
1:12
AM
2:24 AM
3:36 AM
July 2014
4:48 AM
6:00 AM
3.4
Dingwall Pump Station Meter Verification
With no leakage identified on the CVRD transmission leg high presscon line and the Master
Meters shown to be performing well the opportunity presented itself to verify the Dingwall
P.S. flow meter. The transmisison system was isolated as the Old Chlorination Meter station
and a backfeed set-up to feed the other side of the station. Both pump stations were
started with zero flow, corresponding to the zero flow seen below. Then every 20 mins a
pump was added at Dingwall. The results below were obtained. They clearly show that the
Master Meter East and the Dingwall P.S. meter recorded the same flows taking into account
an uncertainty of ±2% for each meter.
2000
Comox Dingwall PS Meter flow verification
1800
1600
East Meter SCADA
Dingwall PS
Flow rate (m3/hr)
1400
1200
1000
800
600
400
200
0
2:24 PM
-200
2:32 PM
2:41 PM
2:49 PM
2:58 PM
3:07 PM
3:15 PM
3:24 PM
3:33 PM
Time (hr:min)
variance = ± 4%
Page 11
July 2014
4
COMPARATIVE FLOW TEST - LEAKAGE MEASUREMENT - HYPRESCON LINE
To try and directly measure leakage on the Hyprescon line the 126 PZ was isolated at the Old
Chlorination Meter station and a backfeed set-up to feed the other side of the station from
the 110 PZ. Both pump stations were started with zero flow, corresponding to the zero flow
seen below. The Master Meters and Dingwall PS meter have been verified as being
accurate. With the manipulation in place, zero flow for the Master Meters while Dingwall PS
& Ryan Rd PS meters are zero indicate no leakage in the Hyprescon line.
Hyprescon Line Direct Leakage Measurement
200
East Flow (m3/hr)
West Flow (m3/hr)
Dingwall PS Flow (m3/hr)
Ryan rd PS meter
150
Flow (m3/hr)
100
50
0
11:31
-50
11:38
11:45
11:52
12:00
12:07
12:14
12:21
12:28
12:36
Time (hr:min)
Page 12
July 2014
5
PRESSURE TRANSIENT LOGGING
As an added value item which could be readily accomplished a “fast logging” cla-val 142PT logger was deployed on the West header at the
Chlorination Station. The logger will record at a high frequency of 8 times per second when a pressure transient is detected. The deployment
of the logger on the West header would reveal if any excessive pressure surges were present at the Chlorination Station end of the Hyprescon
line which would presumably be emanating from the Ryan Rd or Dingwall Pump Station operating cycles.
An unfortunate issue with these loggers is the time stamp. Hence the actual time on the x-axis is not displayed. The period shown covered
approximately 6 weeks from the end of August to early October. The true extent of the pressure fluctuations is significant with 60-140 psi
experienced during single events with a median of 116 psi. This is not unexpected considering the nature of the pumping regime. Larger
transmission mains are rated for the maximum pressures seen with a factor of safety however weaker points, like service connections directly
off the main, may see damage over time. Also any weaknesses which develop in the main line will propagate quicker because of the transients.
Page 13
July 2014
The close up below does reveal that after the initial maximum pressure fluctuations the transient does bounce up and down the line, with
regular frequency but diminishing amplitude.
Peak
Trough
There is typically 10’s of seconds between the peaks and the troughs with the extremities being reached for up to a few seconds.
Page 14
July 2014
6
SUMMARY OF RESULTS
The results of this work phase span across bulk meter verifications, leakage level findings
and operational findings.
6.1
Meter Accuracy Verifications
The Meter Verification based on instantaneous flows anly had the following Findings;
 Master Meter East – Passed Accuracy Test.
 Master Meter West – Passed Accuracy Test.
 Dingwall P.S. – Passed Accuracy Test.
 Under-registration of Water Supplied to the CVRD Transmission System is not
originating at the Master Meters or Dingwall P.S. meter. The other significant bulk
meters left under suspicion are;
o Ryan Rd P.S.
o Courtenay #1
o Comox #1
o Comox #2
6.2
Hyprescon Leakage
Zero Leakage has been confirmed on Hyprescon line.
6.3
Master Meter Circulation
Circulation is occurring through the East Master Meter (+ve) and West MM (-ve) when
nothing is calling. One night of 5 second data from our ultrasonic meters shows that the circulation
was consistently present between reservoirs calling, up to 3 hours duration. The period where the
East Master is properly recording the circulating 50 m3/hr is where an error is being accrued.
However, after a period of time, sometimes several hours, the East Mag meter stops recording the
flow. Actually at this point the East Meter is under-registering but so is the West meter by missing
the negative flow meaning that these errors actually cancel each other out.
In response to the circulation a valve upstream of the chlorination building has already been closed.
Page 15
July 2014

Appendix C Master meter verification

Transcription

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