Choosing a conductivity logger
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Hosted by Paul Gannett, a product marketing manager at Onset, this presentation highlights five important considerations in selecting and deploying a conductivity logger, including the following: Accuracy considerations Ease of deployment and offload Software capabilities Cost of ownership Deployment considerations
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Choosing a conductivity logger
- 1. onset® Choosing a Conductivity Logger: 5 Important Considerations Presented by: Paul Gannett Product Marketing Manager, Onset HOBO® 1 1 7/20/2010 ONSET COMPUTER
- 2. onset® Choosing a Conductivity Logger: 5 Important Considerations Accuracy considerations Ease of deployment and data offload Software capabilities Cost of ownership Deployment considerations HOBO® 2 7/20/2010 ONSET COMPUTER
- 3. onset® Choosing a Conductivity Logger Accuracy considerations How prone is the sensor to drift? (Non-contact sensors have less drift than sensors that use electrodes) Does the logger software include compensation for measurement drift from fouling? How easy is it to clean the sensor of any fouling? What is the logger’s temperature accuracy and response time? … Every 0.5C of temperature error causes 1% error in specific conductance HOBO® 3 7/20/2010 ONSET COMPUTER
- 4. onset® Choosing a Conductivity Logger Ease of deployment and data offload Does the logger sink or float? Deployment in wells is easier if the logger sinks The smaller the logger, the easier it is to deploy How is the logger be mounted? An eyelet makes it easy to hang in wells Waterproof data shuttle for convenient offload Ground level Conductivity logger Water level HOBO® 4 7/20/2010 ONSET COMPUTER
- 5. onset® Choosing a Conductivity Logger Software capabilities Look for software that makes it easy to configure your logger and analyze data: Conversion to specific conductance with choice of temperature compensation methods Entering field calibration readings – preferably from both the start and end of deployment Multi-logger graphing and analysis Easy data export Project save and recall HOBO® 5 7/20/2010 ONSET COMPUTER
- 6. onset® Choosing a Conductivity Logger Cost of ownership Be sure to consider features that save you time or extend the life of your logger Software that can compensate for drift means you don’t have to go into the field as often to take calibration readings Regular sensor cleaning extends the logger’s life – look for one that is easy to clean Replacement batteries and sensors extends the life of your logger Using a waterproof shuttle avoids risking your laptop in the field The cost of stand-alone conductivity loggers is coming down, with some below $700 HOBO® 6 7/20/2010 ONSET COMPUTER
- 7. onset® Choosing a Conductivity Logger Deployment considerations - Mounting The logger should be placed in a location that has good, continuous water flow, if possible Mount the logger so that the sensor face is vertical to water flow to prevent air bubbles from forming on the sensor Keep the logger at least an inch from metal surfaces HOBO® 7 7/20/2010 ONSET COMPUTER
- 8. onset® Choosing a Conductivity Logger Deployment Considerations - Maintenance Clean the sensor with a cotton swab and mild detergent whenever possible – particularly in fouling environments You will need a calibrated conductivity meter for field measurements HOBO® 8 7/20/2010 ONSET COMPUTER
- 9. onset® Choosing a Conductivity Logger HOBO Conductivity Logger The HOBO U24 Conductivity Logger is a high-accuracy, cost effective data logger for measuring conductance and temperature in streams, lakes, and other freshwater sources. HOBO® 9 7/20/2010 ONSET COMPUTER
- 10. onset® Choosing a Conductivity Logger HOBO Conductivity Logger Durable, non-corrosive Delrin® housing Non-contact sensor that is easy to clean Optical interface provides high-speed, reliable data offload in wet environments Compatible with HOBO Waterproof Shuttle for easy and reliable data retrieval HOBOware Pro software provides drift compensation using calibration points from the start and end of each deployment and accurate conversion to specific conductance for the water type $699 HOBO® 10 7/20/2010 ONSET COMPUTER
- 11. onset® Choosing a Conductivity Logger Questions and Answers HOBO® 11 7/20/2010 ONSET COMPUTER
- 12. onset® Choosing a Conductivity Logger Webinar To discuss your upcoming monitoring project in greater detail, please contact us: Tel. (800) LOGGERS (564-4377) Email: sales@onsetcomp.com Or visit us at onsetcomp.com Questions and Answers HOBO® 12 7/20/2010 ONSET COMPUTER
- 13. onset® Choosing a Conductivity Logger HOBO U24 – Main Specifications HOBO® 13 7/20/2010 ONSET COMPUTER
Notas do Editor
- Good afternoon!Today I would like to talk about considerations to keep in mind when you are trying decide what conductivity data loggers are best for your needs.
- Basically the considerations fall into these 5 categories….
- When considering accuracy, you need to keep in mind the reality of leaving loggers in water for an extended time. There will be fouling, which is the buildup of sediment, algae and slime. You can’t avoid this fouling. No matter how accurate the logger is, fouling is going to effect measurement accuracy. The key is to choose loggers that help you deal with these real-world challenges. Here are some features to look for in loggers … Non-contact sensors are not as effected by fouling as electrode-based sensors. Electrode sensors directly measure conductance between the electrodes, and any fouling or tarnishing is directly in the conductance measurement path, which directly effects the measurement. In the case of non-contact sensors, the sensor is not in contact with the water, so there is no chance for tarnishing, and any fouling only has a secondary effect on the conductance measurement. To compensate for drift and fouling, it is critical that the logger software provides a way to enter calibration readings taken at the site with a calibrated meter. Fortunately, most logger software provides a way to enter a calibration reading. Because the residue on the sensor changes over the course of the deployment, it is even better if the software allows entering two calibration points, one from the beginning of the deployment period and one at the end. each time that readout the logger, you should clean off the sensor, so you should look for a logger that has a sensor that is easy to clean as is being done here. Because the conductance of water changes with temperature, conductivity data is always adjusted to specific conductance at 25C. In order to do this conversion accurately, you need to have an accurate water temperature measurement taken right at the sensor.
- Here are some features to look for that make loggers easier to deploy: Loggers that sink are easier to deploy because you can just hang them in the water. Look at the size of the logger. Obviously, the smaller the easier they are deploy. Look at how you can attach them. A mounting eyelet make them easy to hang or attach. Having the option of waterproof shuttle makes it a lot easier to offload the data
- Software is key! Software is your interface to the logger and tool for analysis. Here some software features to look for:Conversion to specific conductance. Most loggers do this, but make sure that the software supports the conversion method for the type of water you are monitoring. Make sure the software allows you to enter calibration readings for adjust your measurements for drift and fouling. This is key for achieving the best accuracy as I mentioned before. … and for once you’ve got the accurate data, look for software that make easy to analyze the data, with flexible graphing, that allows you to compare data from multiple sites … and with the option to export it. It’s also nice to have software that allows you to save your graphed data, and later recall that for comparison with new data.
- Saving time is saving money, so look for features that will save you time like software that can compensate for drift. Keeping your sensors clean can extend their life, so as we’ve already mentioned, look for sensors that are easy to clean. Also in the vein of extending the life of your logger, being able to replace your sensor and battery allow you to use the logger for many years. Having a data shuttle that you can take into the field instead of your laptop is good too. Having your laptop fall into a stream can be expensive to replace, to say nothing of the lost data. And lastly you should be happy to hear that the cost of conductivity loggers are coming down, with some under $700 now.
- In planning for deploying your conductivity logger, here are some things you should keep in mind:Make sure you have locations that are accessible and have a good water flow. If your sensor has a flat face, it will need to be mounted vertically so it sheds air bubbles. For mounting you want to avoid metal. PVC pipes and zip ties are great for mounting. Here you can see a couple conductivity loggers mounted in a perforated PVC pipe that protects the loggers form debris, and the holes insure good water flow. The pipe is zip-tied to the stake.
- Other things you will need are a handheld meter for taking conductivity readings at the site, and cotton swabs to clean the sensor. A typical site visit will consist of calibrating you field meter before going out, and then at the site measuring the actual conductivity, reading out the data and cleaning the sensor.
- One example of a conductivity data logger is the HOBO conductivity logger, which is for freshwater environments up to 10,000 us/cm.
- Go through list pointing out each item.
- That’s all I had to present for now, because I wanted to save some time for questionsDid Jennifer already tell them how to submit their questions? If there any that I don’t have the answer for today, just make sure that I have your email address, and I will get back to you.
- Well, my time is up. Thank you for attending our webinar today. I hope that I’ve provided you some information that will help you in selecting and deploying conductivity loggers.