hydrological services pty ltd sydney, australia bill barratt ceo aha conference july,04 © copyright
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Hydrological Services Pty LtdSydney, Australia
Bill Barratt
CEO
AHA Conference July,04
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Old Vs New
-40oC Float WellsHistory Of Gas Purge System
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Skeppsholen Maregraph
Continuous Water Level Records Since 1755
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Skeppsholen Maregraph cont’
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Skeppsholen Maregraph cont’
Late 1700’s These Records Were Used To Show That The Swedish Land Mass Was Rising About 50 mm Per Year
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Skeppsholen Maregraph cont’
In 1765 Mr Celsius Commenced Air Temperature Measurements At This Site
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Float Well
IN SWEDEN FLOAT WELLS OPERATE IN TEMPERATURES DOWN TO –40oC.
THERE ARE TWO TYPES OF FLOAT WELLS:
1. HEATED FLOAT WELLS
2. UNHEATED FLOAT WELLS
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Heated Float Well
• 380 VAC Power.
• Hut Temp +10oC.
• Air Heater.
• Air Blower In Well.
• Heating Element In Inlet Pipe.
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Heated Float Well Cont’
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Unheated Float Well
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Gas Purge Systems
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Gas Purge Systems Cont’
Developed By Dutch Engineer Late 1940’sAdopted By U.S. State Of Illinois Water
Group in 1954.
(Re: Bubbler System Instrumentation For Water Level Measurements, By Gerald H Nelson, 1954)
USGSAustralia , Des Sherlock Late 1950’s
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Gas Purge Systems Cont’
Early Instruments:Miriam Site Glass Bubble Units
Bottled Dry Nitrogen or CO2
Exactel Servo ManometersU.S.G.S Servo Manometer
( In Australia known As Stevens)
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Gas Purge Systems Cont’AUSTRALIA: Qld Developed Their Gas Electric Manometer To
Get A Larger Range In Late 50’s Des Sherlock Developed The Sherlock Pressure
Sensing Unit 1965-68 Using The Force Balance Principle.
GCO, For Use With Gas Purge Or As A Fixed Open Bell System.
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Gas Purge System Cont’
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Gas Purge System Cont’
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Gas Purge System Cont’
Force Balance System More Accurate, It Measures Water Level Direct
Others Measured Mercury level Changes
- A Factor Of 13.7
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Gas Purge Systems Cont’
1972 Sherlock & Holmes Paper On P.S.U.
In GermanyNext Year A U.S. & A Germany Copy Were
Marketed Neither Achieved P.S.U. Accuracy Or Reliability
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Gas Purge System
1978 H.S. 50 Metre Model Built For Dam Storage levels
1982 H.S. Found HS-22 And Miriam Bubble Units Were Unstable At Bubble
Rates Lower Than 80 Bubble/Minute
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Air Compressor System 1982-1988 H.S. Developed New
Differential Regulator Stable At Bubble Rates From 5 B/Minute to 200 B/Minute
1989 Dry Bubble Unit (No Sight Glass) Early 90’s Parascientific Developed High
Resolution Dry Pressure Transducer Accuracy Similar To PSU.
Mid 90’s Gas Purge Compressors First A Company In New York
Then a UTAH And French Co.
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Air Compressor System Cont’
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Air Compressor System Cont’
1998 - H.S. Had A Contract To Supply 28 Units To a Sth. East
Asian Country
- Intended To Buy In And Re-Badge
- On Testing None Would Operate To Our Requirement
- In Six (6) Weeks We Developed HS-55
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Air Compressor Systems
Air Compressed Water Is ProducedMust Be Dried After Compressing H.S Only Manufacturer In The World To
Do This.
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Air Compressor System Cont’
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Air Compressor System Cont’
Range Water Level 0-30 MetresRiver Lines Up To 200
MetresOperating Temp -30 to +70oCHumidity up to 100%
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Air Compressor System Cont’
1998-2004 Proliferation New Models With Small Capacity
Gas Storage Tanks New Type Instantaneous Purging Compressor
Most With Inbuilt Pressure Transducers. None Dried Air After Compressing It Unreliable In High Humidity Conditions Moisture In River Line Insufficient Storage And/Or Compressor Capacity
To Purge River Line Dry.© Copyright
Air Compressor System Cont’
At H.S. From 1984 Experimented With Pressure
Transducers Technology Wasn’t Until 1998 We Saw Possibility Of Making A Pressure Transducer With Similar Accuracy As The PSU
I Visited Druck In U.K. In 1998 Negotiated Supply Of O.E.M Strain Gauge
Modules Druck Advised Us On Processing These Elements
– Remove Initial Drift– Stabilise Output © Copyright
Air Compressor System Cont’
H.S. Developed Signal Process– Initially 4-20 mA Output– Then Voltage– Now RS232 & SDI-12
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Air Compressor System Cont’
23/7/04 WL3100 Firmware To Accept Inputs
– Latitude– Altitude– Average Water Temperature– Height Of Instrument Above OrificeAnd User Factor Is Calculated To Adjust Our Factory
Calibration To Any Site In The World. This Is Similar To What Parascientific Do
We Now Feel We Have A Pressure Transducer With Equivalent Accuracy To Our PSU
However, It Will Not Have Longevity Of PSU© Copyright
Gas Purge Compressor Cont’
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Lattitude error
0
0.1
0.2
0.3
0.4
0.5
0.6
0 10 20 30 40 50 60 70 80 90
Lattitude (deg)
% Error
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Altitude Error
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
Altitude (m)
% Error
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Water Temp Error
-0.3
-0.25-0.2
-0.15
-0.1
-0.050
0.05
0 5 10 15 20 25
Water Temp (C)
% Error
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Error due to Equip Height Above Orifice
-0.4
-0.3
-0.2
-0.1
0
0 5 10 15 20 25 30
Equip Height (m)
% Error
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New Technologies
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Conclusion
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