After just a short time, the HQD digital electrochemical measuring system has already established itself in practice, both in the laboratory, with standard electrodes, and in the field, with rugged outdoor electrodes.

Various user experiences show that the system covers a wide range of applications, including direct measurement with long-cable outdoor electrodes in sewage treatment plants and surface waters. The simple handling of the meter and the electrodes is also rated very highly.

“We have been using the HQ11D for a while now. Besides the simple handling, the digital technology was the decisive factor. With previous instruments, the contacts between the meter and the electrode always corroded. This problem no longer occurs, thanks to the HQD electrode’s efficiently insulated plastic connector,” says Hans Seidler from Saint-Gobain Vetrotex.

What does HQD mean?
HQD stands for High Quality Digital, which means that the processing of the values measured by the electrodes is digital rather than analog.

What are the advantages of the digital technology?
All calibration data is now stored in the electrode and not, as used to be the case, in the measuring instrument. This means that the electrode can be connected to any other HQD meter after it has been calibrated and is then immediately ready for use without being recalibrated. This is very convenient and time-saving, especially when several instruments are in use at different measurement locations.

Whatever the parameter (pH, conductivity or oxygen), the electrode is connected to the meter in the same way, and the meter automatically recognizes it (Intellical electrode).

Intuitive operation
The menu-guided, operator interface makes using the instrument self-explanatory.

Even users with no experience of the instrument can easily obtain precise and reliable pH, conductivity and oxygen readings with the HQD system.

Up to 500 readings can be stored in the instrument and subsequently transferred to a printer or a PC.

Calibration of the HQD electrodes is equally simple and reliable using the Hach buffer and standard solutions for pH and conductivity. The ready-to-use solutions are available in a variety of concentrations, package sizes and package types, including 500 mL bottles for frequent use, and 25 mL Singlet pouches.

Rugged outdoor electrodes for on-site measurements
The rugged stainless steel outdoor electrodes are extremely practical for on-site analysis. Thanks to the digital technology, they can be used with cables up to 30 meters long (even for pH measurements). This eliminates the problems of inaccessible measurement locations and the weighted rugged probe can easily be immersed. The waterproof electrodes are impact resistant and provide reliable results even over long distances.

Tips for using outdoor electrodes:

• Wear gloves.
• Take dry cloths with you to wipe the probe after use, as there is usually no water available for rinsing.

How do users rate working with the HQD system?
Here are some comments from participants at recent Hach electrochemistry seminars:

“I think it is good that the keyboard has such a clear layout and the operation of the meter is so easy to pick up.”

“The user manual is hardly ever needed after just a brief familiarization period.”

“It’s great that the meter has such a large memory and the data can be transferred to a PC. I don’t need any paper, which always gets wet anyway, when I am in the field.”

“With the outdoor electrodes and the different cable lengths, I can take readings directly at all measurement locations.”

“It’s excellent that the meter shows the individual work steps during calibration.”

“The reading stabilizes more quickly than when the old analog electrodes were used.”

“At last I don’t have to carry out polarization or calibration in order to measure oxygen. Also, less maintenance is needed and the electrodes suffer less wear.”

“With my HQ40D multi I can connect two additional electrodes at the same time and read both values simultaneously.”

Special characteristics of the HQD system

• Oxygen measurement with an HQD meter is carried out using the proven drift-free LDO method. This means fast response times, stable results without prior calibration and no time consuming changes of the electrolyte and membrane.
• The user menu of the HQD meter can be selected from 10 different languages.
• The HQD meter displays a stabilization bar to indicate the progress of the measurement.
• The user can set the frequency and quality of the calibration to suit the measurement situation.
• The Intellical electrodes automatically remind the user when a new calibration is necessary.
• The HQD meter has a control standard program with which the Intellical electrode can be easily checked before each measurement.

For more information visit www.hach.com.