Instructions and Care

Take care of your sensor to ensure reliable measurements and a longer lifetime

Prior to installation, it is optimal to keep the sensor at room temperature. However, our sensors will usually survive in a temperature bracket between -10C and 60/70C, provided that the glass membrane (the small glass tip) does not dry out.

Read this page to learn more about how to work with your sensor more efficiently. 

Calibration

Frequency of calibration mainly depends on how accurate your measurement needs to be, and how rigorous your process is. In other words, if you dip a sensor in a pH 4 solution/buffer and it measures 4.03, then you can assume it’s working fine. However, if it measures 3.8, then there is a good chance you will need to readjust it. Be aware that you should use a buffer with a value close to your expected measurement in the process. Depending on the accuracy of your measurement, you can then assess the situation. Another rule of thumb is: if you find discrepancies in the range of 0.1-0.2 in a water process, this should not be an issue for most uses. However, this may not be accurate enough for applications in the pharmaceutical industry. When measuring waste water, a discrepancy of 0.4 may still be acceptable. Essentially, it depends on your process or application.

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Calibration Process

Before you begin, make sure you observe any regulations in place (and/or follow best practices) pertaining to your particular conditions/environment, especially if the process is hazardous.

We offer buffers at different pH values. Use them to test and adjust your sensors, regardless of whether they’re digital, analogue, or from a different brand. 

For the lab in particular, we also offer software called Memobase+, which will turn your PC into a calibration laboratory and provide complete traceability of test solutions, sensors, calibrations and measurements.

To support your calibration in the field, we created Liquiline To Go, a “portable transmitter”. You can connect your sensor to it and measure your sample with a sensor identical to the one used in the process (and calibrate it).

How is the Sensor Calibrated?

  • Take the sensor out of the process
  • Clean the sensor
  • Flush the sensor with deionized/distilled water
  • Pour the buffer into a clean beaker
  • Put the sensor into the beaker with the buffer
  • Read the value on the display
    – if it matches the buffer value (within an acceptable range), you’re all set
    – if it doesn’t, adjust the value through the transmitter or swap to a freshly calibrated sensor
  • Flush the product again with deionized/distilled water
  • Go through the same process with the second buffer
  • Flush the sensor
  • Put it back in the process

Avoid Unscheduled Downtime

There are many approaches to avoid any unscheduled downtime of your sensor:

  • Take care of your sensor – clean it regularly, calibrate it and regenerate it whenever possible.
  • Install redundant sensors – having more than one sensor in the same area of your process will ensure continuous measurements, even in the case of breakages (you can set an alarm in the transmitter to alert you if the discrepancy between the two is more than 0.x%).
  • Study your sensor’s history – understand which parts of your process consume your sensor the most and prepare accordingly.

Clean Your Sensor

Cleaning a sensor is a simple process. However, it is important that you to pay attention to the kind of process the sensor was in.  In some cases, water is enough to clean the sensor. At other times, you will need cleaning solutions (e.g. in a dairy process measuring milk you will need to get rid of proteins – in which case dishwashing liquid with hot water is usually sufficient).

More intense processes may require the use of more than one cleaning solution (e.g. in sticky crude oil applications you will need to clean the sensor with naphtha first, and then get rid of metal oxides with an acid).

  • The sensor should never be dry. It’s not dry even when you first take it out of the box. Drying a sensor will damage it.