detergent and then lightly scrub the electrode for a few seconds or so. For a more aggressive coating of the sensor and one in which the detergent cleaning does not suffice, you may have to dip the brush in a 2% HCI acid solution and then lightly scrub the electrode for a few seconds or so to facilitate cleaning. Alternatively, you may have to allow the sensor (electrodes) to soak in a similar solution for a few minutes to really work at attacking the contaminant.
Immediately after cleaning, rinse the sensor in water and allow it to soak in tap water or a 7pH buffer solution for a few minutes to allow the pH sensor to stabilize.
General cleaning procedure: 1. Keep the sensor as reasonably clean as possible.
2. Remove the bulk of contaminant by carefully blotting/wiping away debris. Be careful not to rub too vigorously as this may cause static charge.
3. Rinse the sensor in warm tap water or distilled water.
4. Prepare a cleaning solution contain- ing a soap and water mixture. Use dishwashing detergent and warm water. Use only soaps that do not contain abrasives or lanolin.
5. Soak the sensor in this solution for up to five minutes and then gently, or while soaking, use a soft bristle brush to gently scrub the bulb and refer- ence area of the sensor.
6. Rinse the pH sensor in warm tap water and check/standardize the sensor in buffer solutions.
Then, if the readings in buffers are still out of tolerance: 7. Soak the sensor in 5% to 10% HCI acid solution for a few – less than five – minutes.
CAUTION: Do not use this procedure if the sensor has been used in a solution containing cyanide as this may produce poisonous cyanide gas. 8. Rinse the sensor in warm tap water and then place it into a mild soap solution for a minute or two to neutralize any remaining acid and let the sensor come to equilibrium.
9. Rinse in warm tap water and check/standardize the sensor in buffer solutions.
Should the above procedures yield results that are within your operational tolerances, the pH sensor is once again suitable for use. However, if the above results do not bring the readings of the pH sensor within tolerance, it is time to replace the sensor.
Endress+Hauser
www.uk.endress.com
Tinytag Data loggers: reliable
and cost-effective monitoring Tinytags are robust, cost-effective, battery operated loggers used to monitor temperature, humidity, power usage, CO2 and other parameters across a variety of industries.
Tinytag Energy Logger: this non-invasive, device is designed for safely monitoring single and three phase power usage in individual devices or complete installations. Portable and self-configuring, it is available as a hand-held unit for spot checks or as a data logger for longer term assessment. (Kit: £795 +VAT).
Tinytag Ultra 2 Thermocouple: supporting type K, J, T and N thermocouples, this battery powered logger provides fast response, versatile monitoring from -200°C to 1370°C, with a built-in temperature channel allowing simultaneous monitoring of process and ambient temperatures. Its connection supports standard and miniature thermocouple plugs. (Starter Pack: £130 + VAT).
Data is downloaded to a PC via a USB connection and viewed with easy to use Tinytag Explorer software. Also available, the Tinytag Radio System that uses wireless communications.
Gemini Data Loggers (UK) Ltd. Tel: 01243 813000
Web:
www.geminidataloggers.com measurement & sensors directory 2012-2013
Next-generation steam flow meter offers unprecedented accuracy to support energy-saving initiatives
pirax Sarco brings unrivalled accuracy to steam metering with its TVA steam flow meter.
S
The TVA flow meter is a stand-alone unit that integrates flow sensing device, temperature sensor,
connection
accessories and flow computer into a compact unit, eliminating the need for additional external equipment.
With a 50:1 turndown, the TVA flow meter provides accurate measurements down to 1/50th of its maximum flow rate, ensuring all steam energy consumption can be accounted for.
The performance and reliability
advantages of the Spirax Sarco TVA flow meter are backed by a three-year warranty and comes in DN50, DN80 and DN100 sizes and is suitable for use in steam systems up to 32 bar g.
For more information on the TVA flowmeter
please call 01242 535319 or email
uk.enquiries@uk.spiraxsarco.com 11
Feature pH sensors A graphic
interpretation of the procedures outlined in the text
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