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METER AQUALAB TDL Manual

Water activity meter
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  • Page 1 AQUALAB ©...

  • Page 2: Table Of Contents

    18286-02 7.19.2021 TABLE OF CONTENTS 1. Introduction ....................1 2. Operation ....................2 2.1 Installation ....................2 2.2 Sample Preparation ...................3 2.2.1 Sample Composition ................4 2.2.2 Sample Temperature ................5 2.3 Taking a Reading ..................6 2.4 Viewing Data ....................8 2.5 Setting Up Isotherm-Determined Moisture Content ........9 2.6 Performing a Linear Offset ...............15 3.
  • Page 3 4. Service .......................37 4.1 Verification and Calibration ..............37 4.1.1 Water Activity Verification .............37 4.1.2 Linear Offset ..................39 4.1.3 Multipoint Calibration ..............41 4.1.4 Restore Factory Defaults ...............44 4.2 Cleaning ....................45 4.2.1 Cleaning Kit ..................46 4.2.2 Cleaning Procedure ................47 4.3 Maintenance Packages ................48 4.4 Repair ......................48 4.5 Troubleshooting ..................49 4.6 Customer Support ..................51...

  • Page 5: Introduction

    This manual includes instructions for the AQUALAB TDL and AQUALAB TDL 2. For simplicity, both will be referred to as "AQUALAB TDL" and all instructions in this manual apply to both instruments: setting up the instrument, verifying its calibration, preparing samples, and taking readings as well as instructions on proper care, maintenance, and cleaning.

  • Page 6: Operation

    Please observe the following considerations carefully. • Only allow personnel qualified by METER to carry out service work on the electrical components. A Certificate of Calibration will be issued upon completion of the work.

  • Page 7: Sample Preparation

    Completely cover the bottom of the cup, if possible, to provide enough sample to get an accurate reading. The AQUALAB TDL is able to accurately measure a sample that does not (or cannot) cover the bottom of the cup. For example, raisins only need to be placed in the cup...

  • Page 8: Sample Composition

    OPERATION A larger sample surface area increases instrument efficiency by providing more stable infrared sample temperatures. It also speeds up the reading by shortening the time needed to reach vapor equilibrium. Do not fill the sample cup more than half full. Overfilled cups can contaminate the chamber and do not make the readings faster or more accurate.

  • Page 9: Sample Temperature

    The most effective way to test these types of samples is to run them in the AQUALAB TDL using Continuous or Custom mode and wait for the water activity readings to stabilize.

  • Page 10: Taking A Reading

    ±0.005 a  accuracy. CAUTIONS • Never leave a sample in the AQUALAB TDL after a reading has been taken. The sample may spill and contaminate the instrument chamber if the instrument is accidentally moved or jolted. • Never move the instrument after a sample has been loaded. Movement may cause the sample material to spill and contaminate the sample chamber.
  • Page 11 Length of read times may vary depending on temperature differences between the chamber and the sample as well as on other properties of the sample (Section 2.2). The default AQUALAB TDL reading cycle continues until the rates of change of three consecutive intermediate readings are <0.0005 a of each other.

  • Page 12: Viewing Data

    OPERATION Figure 4 Keyboard screen to annotate data results 2.4 VIEWING DATA To view prior test results, use the following steps: Press MENU to navigate to the Data tab (Figure 5). Figure 5 Data tab Select ENTER. Scroll through the list of saved tests using UP and DOWN (to move one item at a time) or RIGHT and LEFT (to move a page at a time) (Figure 6).

  • Page 13: Setting Up Isotherm-Determined Moisture Content

    METER recommends offsetting the model to a primary reference method (Section 2.5). Once a moisture model is loaded on the AQUALAB TDL, it will return a moisture content reading. Until a linear offset has been performed, this moisture content value should not be considered precise and should be discarded (Section 2.5).
  • Page 14 OPERATION Select Products from the SKALA Main menu to open the Product groups page (Figure 8). Figure 8 SKALA Main Menu Select the product group that contains the product to be added as a model (Figure 9). Figure 9 Select product Select the product. Click the edit icon on the product row (Figure 9).
  • Page 15 AQUALAB TDL/TDL 2 Figure 10 Edit Product screen Scroll to the Moisture Content Model section of the Edit Product screen (Figure 10). Click on the Add Model link (Figure 11).
  • Page 16 Custom model using data on the Custom Isotherm Model Coefficients sheet received from the METER Food Lab. To set up a custom model, follow step 9. METER has created dozens of isotherms and compiled them into the SKALA isotherm library. Contact Customer Support with questions about the preset isotherm models.
  • Page 17 AQUALAB TDL/TDL 2 Figure 12 Predefined model Under Market group, select the general classification for the type of model (Figure 13). The first time the Product is edited, the list of Market groups will be quite long. A maximum of two market groups can be selected and a dialog will appear to confirm the selections.
  • Page 18 Before taking moisture content readings, perform a linear offset (Section 2.6). To set up a custom model, the Custom Isotherm Model Coefficients sheet must be received from METER Food Lab. The information on the sheet will be added manually into SKALA. Contact Customer Support if the sheet was not received.

  • Page 19: Performing A Linear Offset

    Divide the large sample into three subsamples, ensuring that each is representative of the larger sample. Place one subsample into a sample cup. Read the water activity using the AQUALAB TDL (Section 2.5) and make a note of the water activity value.
  • Page 20 OPERATION This will be used in step 13. NOTE: The moisture content value has not yet been properly offset and should be ignored. Use the reference method to determine the average moisture content of the other two subsamples. This average is the reference moisture content value. This will be used in step 14. Open skalacontrol.com.
  • Page 21 AQUALAB TDL/TDL 2 Figure 19 Linear offset section 13. Enter the product water activity from step 5 into the Measured AW field. 14. Enter the reference moisture content value from step 6 into the Measured MC field. 15. Do NOT enter a value into the Linear Offset field.

  • Page 22: System

    SySTEM 3. SySTEM This section describes the AQUALAB TDL Water Activity Meter. 3.1 SPECIFICATIONS MEASUREMENT SPECIFICATIONS Water Activity 0.000–1.000 a Range 0.0001 a Resolution Accuracy ±0.005 at 25 °C Temperature Range 15–50 °C Resolution 0.01 °C Accuracy ±0.1 °C Adjustment Increment 1 °C...

  • Page 23: Components

    EM ISO/IEC 17050:2010 (CE Mark) 3.2 COMPONENTS The AQUALAB TDL uses a tunable diode laser to measure the water activity of a sample. The sample is equilibrated with the headspace of a sealed chamber containing a tunable laser that shines light of a controlled wavelength at a detector that receives the light from the laser.

  • Page 24: Cords And Cables

    WARNING: Only use the supplied power cord or one rated for AQUALAB TDL and certified for the country of use. The cord must be a minimum of 18 AWG and have a rating for 10 A or greater.

  • Page 25: Buttons

    Sample chamber interior 3.2.3 BUTTONS The power switch is located on the lower left corner of the AQUALAB TDL back panel. After being turned on, the AQUALAB TDL should warm up for 15 min before operation to ensure accurate readings.

  • Page 26: Display Screen

    Reading results Button icons Reading time elapsed Figure 23 Display screen The button icons on the display change to show the available actions for the screen (Table Table 2 AQUALAB TDL button icons Icon Name Action ENTER Accepts the current action...
  • Page 27 AQUALAB TDL/TDL 2 3.2.4.1 MEASUREMENT TAB The Measurement tab (Figure 24) is the main screen and must be visible to start a reading. Measurement results are displayed on this screen. Figure 24 Measurement tab Using the RIGHT or LEFT buttons changes the display to a temperature equilibration screen (Figure 25).
  • Page 28 • Temperature. Select to set the AQUALAB TDL to the desired temperature using UP and DOWN. When finished, select SAVE (Figure 28). The AQUALAB TDL may be set between 15 and 50 °C in 1.0 °C intervals. The default temperature is 25 °C.
  • Page 29 AQUALAB TDL/TDL 2 Figure 29 Temp Eq • Sensor. This displays the TDL sensor as the active sensor on the Measurement tab. This configuration option is not editable. • Mode. Select to choose between Single, Continuous, Custom, or Low-Emitting mode (Figure 30). The current mode settings appear at the top of the screen with the number of tests appearing first, followed by the stability value (∆a...
  • Page 30 Figure 32 Low-Emitting mode AQUALAB TDL determines vapor equilibrium at the end of a test by comparing sequential water activity values, looking for a trigger value difference <0.0005 a .
  • Page 31 The time is recorded with each water activity reading. Figure 34 Time option • Regional Formatting. Select to configure how the AQUALAB TDL displays information (Figure 35). Choose the temperature scale (Celsius or Fahrenheit), the date display (mm/dd/yy or dd/mm/yy), the hour format (12 or 24 h), and the language.
  • Page 32 The Admin Settings allow the administrator to grant or block access to some or all the configuration options. NOTE: Once the administrator is set up, the password cannot be recovered. The AQUALAB TDL must be sent back to METER to be reset.
  • Page 33 The AQUALAB TDL can store up to 8,000 records before the memory is full. Any individual reading may be saved manually right after completing the test and before beginning the next test, regardless of the Autosave setting.
  • Page 34 SySTEM Figure 40 Diagnostics screens • %Moisture. Select which moisture content model to use to calculate moisture content. • About. Select to view instrument information including the serial number and firmware code version of the instrument (Figure 41). Figure 41 About screen 3.2.4.3 DATA TAB Data can be viewed or deleted from the Data tab (Figure 42).
  • Page 35 AQUALAB TDL/TDL 2 Figure 43 View data summary Select a highlighted reading to view detailed information (Figure 44). Figure 44 Data sample detail screen The screen displays the name of the reading (if annotated), the water activity of the sample, the temperature of the sample, the test time, the user who ran the test (if set up), the reading date, the sensor used, the time the reading was taken, and the sequence number of the stored reading.

  • Page 36: Theory

    In the AQUALAB TDL, a sample in a sample cup is sealed inside the sample chamber, which contains a tunable diode laser and an infrared thermometer.
  • Page 37 4 °C above the chamber temperature to cause condensation to form. The AQUALAB TDL warns the user if a sample is more than 4 °C above the chamber temperature, but for high water activity samples, the operator needs to be aware that condensation can occur if a sample that is warmer than the block is put in the AQUALAB.
  • Page 38 25 °C, though 20 °C is sometimes indicated. Minimization of extreme ambient temperature fluctuations. If the environmental and AQUALAB TDL temperatures fluctuate by as much as ±5 °C daily, water activity readings vary by ±0.01 a . Temperature control eliminates variations due to changes in ambient conditions.

  • Page 39: Water Potential

    AQUALAB TDL/TDL 2 reduced. Work would need to be done to extract the water from this matrix. This reduction in energy status of the water is not osmotic, because the cellulose or protein concentrations are far too low to produce any significant dilution of water. The reduction in energy is the result of direct physical binding of water to the cellulose or protein matrix by hydrogen bonding and van der Waals forces.
  • Page 40 In order to infer moisture content from water activity, an isotherm for the particular product is needed. METER sells an isotherm generator called the AQUALAB Vapor Sorption Analyzer (VSA) or METER can run the isotherm for a fee. Visit metergroup.com/food/services/...

  • Page 41: Service

    AQUALAB TDL performance. Therefore, frequent verification assures that the AQUALAB TDL is performing correctly. In addition, providing a linear offset can be used to overcome any additional instrument drift.
  • Page 42 NOTE: The AQUALAB TDL needs to warm up for approximately 15 min to make accurate readings. Empty a vial of the lower water activity verification standard into a sample cup. Place it in the AQUALAB TDL testing chamber. Make sure that the standard is as close to the instrument temperature as possible (Section 2.2.2).

  • Page 43: Linear Offset

    Figure 47 Verification standard flowchart. A check indicates AQUALAB TDL verified the standard within specification; a cross indicates AQUALAB TDL did not verify the standard within specifications. 4.1.2 LINEAR OFFSET After verification and cleaning the instrument, an offset may be necessary.
  • Page 44 NOTE: To interrupt the offset procedure, return the lever to the OPEN position or select CANCEL to return to the previous screen. After the AQUALAB TDL has finished measuring the verification standard, it displays a Change the offset screen (Figure 50).

  • Page 45: Multipoint Calibration

    (Section 4.1.2) or a multipoint update, which requires reading multiple water activity standards. NOTE: Factory calibrations performed by METER are locked and cannot be updated with a multipoint calibration, only with a linear offset as outlined above. The 0.25, 0.50, 0.76, and 0.92 a unsaturated salt standards are needed to proceed with multipoint calibration.
  • Page 46 Carefully close the lid and move the lever to the READ position. 10. Select OK to begin testing. 11. After AQUALAB TDL has finished measuring the verification standard, a new screen appears requesting that a 0.50 a standard be placed in the chamber.
  • Page 47 AQUALAB TDL/TDL 2 Figure 53 Verification Complete screen with results 13. Select OK to continue or CANCEL to cancel the entire process. NOTE: Select the audio icon to turn beeping on and off. 14. To make adjustments to the calibration, select OK.

  • Page 48: Restore Factory Defaults

    Select OK to continue (Figure 57). Figure 57 Calibration canceled confirmation 18. Measure a 0.25 or 0.50 a verification standard in the Measurement tab. 19. Verify the AQUALAB TDL reads within ±0.005 a at a given temperature. 20. Measure a 0.76 a verification standard.

  • Page 49: Cleaning

    The instrument will confirm the factory calibration has been restored (Figure 60). Figure 60 Confirmation that factory calibration was reset Select OK. 4.2 CLEANING Keeping the AQUALAB TDL clean is vital to maintaining the accuracy of the instrument. Dust and sampling debris can contaminate the sampling chamber, so regular cleaning is essential.

  • Page 50: Cleaning Kit

    SERVICE To clean the AQUALAB TDL, carefully follow these instructions and refer to the labeled diagram in Figure 61. A video is also available at AQUALAB 4TE certification (metergroup. com/meter_knowledgebase/aqualab-4te-certification). Lever Latch Thermopile Tunable diode laser Upper block Laser InGaAs photodiode...

  • Page 51: Cleaning Procedure

    AQUALAB TDL/TDL 2 4.2.2 CLEANING PROCEDURE The procedure to clean AQUALAB TDL involves washing, rinsing, and drying each area. NOTE: Isopropyl alcohol can be substituted for the Cleaning Solution. Turn the AQUALAB TDL power OFF. Open the chamber cover to expose the sample chamber and sensors.

  • Page 52: Maintenance Packages

    Repairs outside of the warranty window are charged based on cost of parts, labor, and shipping. An extra fee may be charged for rush work. Contact Customer Support for an estimated repair cost. METER has loaner instruments available for a fee while the AQUALAB TDL is being serviced.

  • Page 53: Troubleshooting

    AQUALAB TDL/TDL 2 All AQUALAB TDL units returning to METER for servicing must be accompanied with a Return Merchandise Authorization (RMA) number. Prior to shipping the instrument, contact Customer Support to obtain an RMA number. Place the AQUALAB in a plastic bag to avoid disfiguring marks from the packaging.
  • Page 54 Firmware is corrupted. See The firmware on the instrument is corrupted and needs to be Manual for options. reloaded. To download new firmware to the AQUALAB TDL models, the instrument must be serviced by METER (Section 4.4). error message The model selected may not be correct for the product being tested.

  • Page 55: Customer Support

    AQUALAB TDL/TDL 2 Table 6 Troubleshooting the AQUALAB TDL (continued) Problem Possible Solutions Moisture content has not been activated. Moisture content does not show up on the Toggle to the Configuration tab, select %Moisture, and select the Measurement tab appropriate model.

  • Page 56: Terms And Conditions

    NOTE: For products purchased through a distributor, please contact the distributor directly for assistance. 4.7 TERMS AND CONDITIONS By using METER instruments and documentation, you agree to abide by the METER Group, Inc. USA Terms and Conditions. Please refer to metergroup.com/terms-conditions...

  • Page 57: Reference

    AQUALAB TDL/TDL 2 REFERENCE Labuza, Ted P., K. Acott, S. R. Tatini, R. Y. Lee, J. Flink, and W. McCall (1976). "Water activity determination: A collaborative study of different methods." Journal of Food Science 41, no. 4: 910–917.

  • Page 58: Index

    INDEX INDEX data accuracy 6, 18 annotate 7 admin settings 27–29 delete 31 annual calibration service 37, 48 view 8–9, 30–31 autosave 7, 25, 29 Data tab 30–31 date 26–27 beep 22, 29 diagnostics 29–30 calibration 7, 24, 37 email address 51 multipoint 41–44 restore 44–45 fax number 51...
  • Page 59 INDEX continuous 25 temp eq 24 custom 25–26 temperature 24 ISO 25 time 27 specifications 18–19 low-emitting 5, 26 print 29 compliance 19 single 25 measurement 18 moisture content physical 18–19 theory 35 power voltage 19 value 7 temp eq 24 osmotic effects 34 temperature 18, 19, 24 temperature effects 33–34...
  • Page 60 18285-01 1.31.2021 METER Group, Inc. USA 2365 NE Hopkins Court Pullman, WA 99163 T: +1.509.332.2756 F: +1.509.332.5158 E: info@metergroup.com W: metergroup.com METER Group AG Mettlacher Straße 8, 81379 München T: +49 89 1266520 F: +49 89 12665220 E: info.europe@metergroup.com W: metergroup.de...

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