choosing a conductivity salinity logger part 1 of 2
DESCRIPTION
Part 1 of a two-part presentation detailing five important considerations when choosing a conductivity/salinity data logger, presented by Paul Gannett, Product Marketing Manager, Onset Computer Corporation, maker of HOBO data loggers.TRANSCRIPT
Choosing a Conductivity/Salinity Logger: 5 Important Considerations
Part 1 of 2
1
HOBO®
onset®
4/25/2012 ONSET COMPUTER 1
Paul Gannett Product Marketing Manager
Topics
• Onset Overview
• Typical Conductivity/Salinity Applications
• The 5 Considerations
• Q & A’s
HOBO®
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4/25/2012 ONSET COMPUTER 2
Choosing a Conductivity/Salinity Logger: 5 Important Considerations
3
HOBO®
onset®
4/25/2012 ONSET COMPUTER 3
Who is Onset?
• Leader in portable Data Loggers
• Founded in 1981
• 130 employees
• Designed and assembled in Bourne, MA
• Over 2 million HOBO data loggers sold
Energy Management
HOBO®
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ONSET COMPUTER 4 4/25/2012
Field Research
Water Management
Onset Markets
• Coastal and estuary research
• Stream restoration
• Water quality monitoring
• Road runoff
• Agricultural runoff
• Monitoring downstream of mines
HOBO®
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4/25/2012 ONSET COMPUTER 5
Choosing a Conductivity/Salinity Logger:
Typical Applications
• Accuracy
• Mounting
• Ease of deployment and data offload
• Software
• Cost of ownership
HOBO®
onset®
4/25/2012 ONSET COMPUTER 6
Choosing a Conductivity/Salinity Logger: 5 Important Considerations
• Specified accuracy – percent of reading & minimum error
• The logger’s temperature accuracy – Every 0.5C of temperature error causes 1% error in specific conductance and salinity
• Sensor technology – electrodes in contact with water can corrode, especially in salt water. Non-contact sensors have minimal drift.
• Fouling can cause significant measurement drift (next slide)
• Software (covered later)
HOBO®
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4/25/2012 ONSET COMPUTER 7
Choosing a Conductivity/Salinity Logger:
Accuracy Considerations
… plan for it
• frequent cleaning
• antifouling materials
– Biocides/copper
– inert materials
• Use field calibration points from the beginning and end of each deployment to compensate for fouling
HOBO®
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4/25/2012 ONSET COMPUTER 8
Fouling Happens!
Choosing a Conductivity/Salinity Logger:
Accuracy Considerations
• Accuracy
• Mounting
• Ease of deployment and data offload
• Software
• Cost of ownership
HOBO®
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4/25/2012 ONSET COMPUTER 9
Choosing a Conductivity/Salinity Logger: 5 Important Considerations
HOBO®
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4/25/2012 ONSET COMPUTER 10
Choosing a Conductivity/Salinity Logger:
Common Mounting Methods
Stilling Well - In ground or attached to a structure such as bridge or dock
Tether Mount Post Mount
• The logger should be placed in a location that has good, continuous water flow, if possible
• Keep the logger at least an inch from metal surfaces
• PVC pipe and zip ties are great for mounting
HOBO®
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4/25/2012 ONSET COMPUTER 11
Choosing a Conductivity/Salinity Logger:
Mounting Considerations
Features to look for:
• Does the logger sink or float? Loggers that sink are generally easier to deploy.
• The smaller the logger, the easier it is to deploy.
• How will the logger be mounted?
An eyelet makes it easy to hang in wells.
• Can the logger be mounted so that is sheds air bubbles?
HOBO®
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4/25/2012 ONSET COMPUTER 12
Choosing a Conductivity/Salinity Logger:
Mounting Considerations
• Accuracy
• Mounting
• Ease of deployment and data offload
• Software
• Cost of ownership
HOBO®
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4/25/2012 ONSET COMPUTER 13
Choosing a Conductivity/Salinity Logger: 5 Important Considerations
Great for the initial deployment
HOBO®
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Easier for ongoing deployments
Choosing a Conductivity/Salinity Logger:
Deployment Considerations - Calibration
Lab Calibration vs Field Calibration
Lab calibration Field calibration