User manual HANNA INSTRUMENTS HI 98713

[. . . ] c o m 1 Dear Customer, Thank you for choosing a Hanna Instruments product. This manual will provide you with the necessary information for correct use of the instrument. Please read this instruction manual carefully before using the instrument. If you need additional technical information, do not hesitate to e-mail us at tech@hannainst. com or see the back side of this manual for our worldwide sales and technical service contacts. [. . . ] The ultrasonic waves can also break the existing air bubbles, leading to a complication of the degassing process. In order to avoid excess application of the ultrasonic waves you can apply ultrasound until all visible air bubbles are removed, and then measure the sample turbidity. If you are not sure that all air bubbles were removed, apply ultrasonic waves again for a short period of time and then measure the turbidity. Repeat this procedure until the turbidity is increasing instead of decreasing, sign that turbidity of the sample was altered. In order to degas a sample fill a clean cuvet with sample and immerse it (1/2 to 2/3 immersed) in an ultrasonic bath. Only after the degassing procedure is finished, the cuvet can be capped. 17 HEATING THE SAMPLE Use of heat to remove air bubbles, although very effective in some cases, should be handled with care because it can alter the turbidity of the sample. When heating a sample, the volatile components from the sample can vaporize, the suspended components can dissolve or the sample characteristics can change. The best way is to use a warm water bath and immerse the cuvet with sample into the bath. Note: Always cool the heated sample to the original sample temperature before measurement. The heating procedure can be used in combination with vacuum or ultrasonic waves application for a more effective air bubble removal. 18 MEASUREMENT PROCEDURE When taking any turbidity measurements several basic rules should be followed: · Use always cuvets without scratches or cracks because they can cause inaccurate readings. · Cap always the cuvets to avoid spillage of the sample into the instrument. · Keep the lid of the instrument closed when it is not used to prevent dust or dirt entering. · Put always the instrument on a flat, rugged surface when taking measurements. · Do not use too much oil to prevent contamination of the optical system. To take turbidity measurements, follow the next steps: · Turn the instrument ON by pressing ON/OFF. On the secondary LCD the current time appears, if selected in SETUP menu. · Fill a clean, dry cuvet with 10 mL of sample up to the mark, taking care to handle the cuvet by the top. · Wipe the cuvet thoroughly with a lint-free cloth to remove any fingerprints, dirt or water spots. · Apply silicone oil on the cuvet and wipe with a lint-free cloth to obtain an even film over the entire surface of the cuvet. Note: It is very important to oil the cuvet, especially for low turbidity values (< 1 FTU) to hide the glass imperfections that can influence the reading. Align the mark from the cuvet with the sign on the instrument case and close the lid. Note: If you have a cuvet with orientation mark, place the cuvet into the instrument with the orientation mark aligned with the sign on the instrument top. 19 NORMAL MEASUREMENT This type of measurement can be used for regular measurements, when the sample is stable and normal accuracy is required. [. . . ] The backlight will be turn off after 25 seconds since the last key was pressed. The battery life is measured each time the LED is turned on and if the remaining battery life is less than 10%, the battery tag will be displayed blinking on the LCD to warn the user that the batteries need to be replaced. When the batteries are completely discharged, "0% bAtt" message will be displayed for one second and the instrument will turn off. In order to use the instrument again, replace the batteries with new ones or use an AC adapter. [. . . ]