METER AQUALAB TDL Manual Download Page 54

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SERVICE

Table 6 Troubleshooting the AQUALAB TDL (continued)

Problem

Possible Solutions

Readings are slow or
inconsistent

The sample chamber may be dirty. Refer to

Section 4.2

for

directions on cleaning the sample chamber.

The temperature difference between the sample and the block

chamber may be too great. Allow the sample to equilibrate to

instrument temperature. Refer to

Section 2.2.2

Some products absorb or desorb moisture very slowly, causing

measurements to take longer than usual, and nothing can be done

to speed up the process. Refer to

Section 2.2.1

Water activity readings on
verification standards are
too high or too low and a
linear offset adjustment
cannot be made any higher
or lower

The IR sensor, which measures sample temperature, may have

become contaminated. Refer to

Section 4.2

for directions on

cleaning.

The AQUALAB TDL lenses may be dirty. Refer to

Section 4.2

for

directions on cleaning.

Remove sample. Sample is
too hot!

error message

The sample temperature is too high for the instrument to

equilibrate within a reasonable amount of time. Ensure samples are

at the same temperature as the instrument (

Section 2.2.2

Crystal Failure. See
Manual for options.

error message

The crystal that runs the firmware is having trouble starting. Cycle

the power. If this message continues to appear, the instrument

needs to be serviced by METER (

Section 4.4

Verification is not correct

Clean the sample chamber and components. Refer to

Section 4.2

for detailed cleaning instructions.

If verification is still not correct, verify and adjust for linear offset

(

Section 4.1.2

Pressure sensor failure

The pressure sensor used during water activity measurements is

not functioning correctly and needs to be replaced. METER needs

to service the instrument (

Section 4.4

Firmware is corrupted. See
Manual for options.

error message

The firmware on the instrument is corrupted and needs to be

reloaded. To download new firmware to the AQUALAB TDL models,

the instrument must be serviced by METER (

Section 4.4

Moisture content displayed
is not correct

The model selected may not be correct for the product being tested.

Toggle through the available models to find a more appropriate

model.

If the model is correct but not giving correct moisture content

values, it may be necessary to offset the model. See

Section 2.6

for

detailed instructions.

If the model is correct and an offset does not work, it may be

necessary to generate a new model for the product or update an

existing model. For information about updating or generating a

model, contact

Customer Support

Summary of Contents for AQUALAB TDL

Page 1: ...AQUALAB TDL ...

Page 2: ...ewing Data 8 2 5 Setting Up Isotherm Determined Moisture Content 9 2 6 Performing a Linear Offset 15 3 System 18 3 1 Specifications 18 3 2 Components 19 3 2 1 Cords and Cables 20 3 2 2 Sample Chamber 20 3 2 3 Buttons 21 3 2 4 Display Screen 22 3 3 Theory 32 3 3 1 Water Activity 32 3 3 2 Water Potential 35 3 3 3 Moisture Content 35 3 3 4 Sorption Isotherms 35 18286 02 7 19 2021 ...

Page 3: ... 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 4 7 Terms and Conditions 52 Reference 53 Index 54 ...

Page 4: ......

Page 5: ...ying its calibration preparing samples and taking readings as well as instructions on proper care maintenance and cleaning Contact Customer Support with any questions about your TDL Verify all of the listed instrument contents shipped and appear in good condition AQUALAB TDL Water Activity Meter Calibration certificate Power cord USB A to B cable 250 disposable sample cups AQUALAB Cleaning Kit Two...

Page 6: ...et or power strip Only use the fuse type and rating specified for this instrument Section 3 1 If the instrument is used in a manner not specified by the manufacturer the protection provided by the equipment may be impaired PRECAUTIONS METER instruments are built to the highest standards but misuse or neglect may damage the device and possibly void the manufacturer s warranty Before using the AQUAL...

Page 7: ... time between cleanings and help avoid downtime Be consistent in sample preparation methods e g crush grind slice the sample to obtain reproducible results For more information on proper sample preparation for different sample types visit Six AQUALAB sample preparation best practices metergroup com food articles six sample preparation best practices More specific considerations regarding sample co...

Page 8: ...curate readings Contact Customer Support for questions on sample composition Use the following steps to determine if further sample preparation is necessary 1 Take several readings of the sample to see if the readings aw and time stabilize Section 2 3 2 If the readings take less than 6 min to stabilize the sample can be handled normally If the readings take longer than 6 min remove the sample and ...

Page 9: ... below the water activity of these types of samples This causes the sample to release water to the vapor phase and equilibrate with the chamber If the relative humidity of the headspace is greater than the water activity of the sample the sample will require a long period of time to reach equilibrium To reduce test time when testing low water emitting samples see Section 3 2 4 2 to set Low Emittin...

Page 10: ...an example of this screen Figure 2 Temperature difference between sample and sample chamber 2 3 TAKING A READING The AQUALAB TDL provides readings in 5 min or less Readings are reliable providing 0 005 aw 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 jol...

Page 11: ...easurement will display on the screen this is an intermediate reading 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 aw of each other When the instrument has fi...

Page 12: ...a tab Figure 5 Figure 5 Data tab 2 Select ENTER 3 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 Figure 6 List of saved tests 4 Select ENTER The detailed test results screen will appear Figure 7 Tests can also be scrolled through using the arrow buttons on this detailed screen ...

Page 13: ...audit ready For more information visit metergroup com food skala system or contact Customer Support The AQUALAB TDL calculates moisture content values based on water activity readings using a method known as isotherm determined moisture content Isotherm determined moisture content relies on models stored in the SKALA isotherm library or on a custom isotherm model provided by METER Food Lab Because...

Page 14: ...t groups page Figure 8 Figure 8 SKALA Main Menu 3 Select the product group that contains the product to be added as a model Figure 9 Figure 9 Select product 4 Select the product 5 Click the edit icon on the product row Figure 9 The Edit Product screen should appear Figure 10 ...

Page 15: ...11 AQUALAB TDL TDL 2 Figure 10 Edit Product screen 6 Scroll to the Moisture Content Model section of the Edit Product screen Figure 10 7 Click on the Add Model link Figure 11 ...

Page 16: ...ta on the Custom Isotherm Model Coefficients sheet received from the METER Food Lab To set up a custom model follow step 9 8 METER has created dozens of isotherms and compiled them into the SKALA isotherm library Contact Customer Support with questions about the preset isotherm models a In the dropdown box below the Moisture Content Model heading select the Predefined model option Figure 12 ...

Page 17: ...f two market groups can be selected and a dialog will appear to confirm the selections In future sessions the Market group dropdown will only show the two groups selected in the initial product setup NOTE Once Market groups are selected they cannot be changed without contacting Customer Support Figure 13 Market group c Under Product name select the product category that most closely matches the pr...

Page 18: ...od Lab The information on the sheet will be added manually into SKALA Contact Customer Support if the sheet was not received a In the dropdown box below the Moisture Content Model heading select the Custom model option Figure 15 There are several isotherm model types The Custom Isotherm Model Coefficients sheet will identify which type to use Figure 15 Custom model selection b Click the radio butt...

Page 19: ... higher or lower than reference method values over several samples To perform a linear offset select a reference moisture content method to use Acceptable moisture content reference methods include ROS 1 loss on drying and Karl Fischer titration Secondary methods have increased margins of error which will in turn increase the error in AQUALAB TDL moisture content measurements If desired an offset ...

Page 20: ...formed on a product by product basis in the SKALA Control desktop application This functionality does not appear in the SKALA Mobile app Figure 17 SKALA Main Menu 8 Select Products from the SKALA Main menu 9 Select the Product group containing the product to be offset Figure 18 Figure 18 Product group 10 Click the edit icon next to the product to be offset Figure 18 11 Make sure the model has been...

Page 21: ...eference moisture content value from step 6 into the Measured MC field 15 Do NOT enter a value into the Linear Offset field This value will be calculated in SKALA Control from the numbers entered as Measured AW and Measured MC 16 Click the Calculate offset button An offset value will appear in the Linear offset field 17 Click the Save button ...

Page 22: ...0 0001 aw Accuracy 0 005 at 25 C Temperature Range 15 50 C Resolution 0 01 C Accuracy 0 1 C Adjustment Increment 1 C Read Time 5 min PHYSICAL SPECIFICATIONS Case Dimensions Length 26 7 cm 10 5 in Width 17 8 cm 7 0 in Height 12 7 cm 5 0 in Case Material POLYLAC PA 765 ABS with fire retardant Sample Cup Capacity 14 mL 0 47 fl oz Weight 3 1 kg 6 8 lb Display 64 128 graphical ...

Page 23: ...hines light of a controlled wavelength at a detector that receives the light from the laser At equilibrium the relative humidity of the air in the chamber is the same as the water activity of the sample In the AQUALAB TDL the vapor pressure of the headspace in equilibrium is determined by the attenuation of signal strength from the laser caused by the presence of water vapor in the headspace This ...

Page 24: ... have a rating for 10 A or greater The USB cable has one USB A connector to connect to a computer and one USB B connector to connect to the AQUALAB TDL The data from the AQUALAB TDL can be saved to the computer with this connection An RS 232 to USB cable may also be used but is not included 3 2 2 SAMPLE CHAMBER The lever has two positions OPEN handle moved to the right and READ handle moved to the...

Page 25: ...AB TDL back panel After being turned on the AQUALAB TDL should warm up for 15 min before operation to ensure accurate readings There are four arrow buttons LEFT RIGHT UP and DOWN Figure 22 These buttons allow for navigation through the various screens on the AQUALAB TDL The three round buttons have variable uses depending on what icon is represented above them on the display Section 3 2 3 Figure 2...

Page 26: ...ime Figure 23 Display screen The button icons on the display change to show the available actions for the screen Table 2 Table 2 AQUALAB TDL button icons Icon Name Action ENTER Accepts the current action CANCEL Ends the current action MENU Switches between the Measurement Configuration and Data tabs SAVE Saves a setting or a reading OK Accepts the input from the user AUDIO OFF Silences beeping AUD...

Page 27: ...nges the display to a temperature equilibration screen Figure 25 This screen shows the temperature difference between the sample and the lid Figure 25 Temperature equilibration 3 2 4 2 CONFIGURATION TAB The Configuration tab provides a menu of configuration options Figure 26 Use UP and DOWN to move the selection through the various configuration options or LEFT and RIGHT to page through the option...

Page 28: ...ed 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 Figure 28 Temperature option Temp Eq Select to set the acceptable temperature difference between the AQUALAB TDL block and the sample before starting a water activity measurement Figure 29 The range is 0 1 to 4 0 C A setting of 4 0 C begins the measurement when the sample is 4...

Page 29: ...read cycle without further action from the user The machine signals the completion of each reading with a beep A timer on the screen tracks the cumulative read time All readings taken during Continuous mode are saved on the instrument memory if the autosave feature is turned on default ISO 18787 mode reads the sample until the water activity change is equal to or less than 0 0003 aw per minute Cus...

Page 30: ... at the end of a test by comparing sequential water activity values looking for a trigger value difference 0 0005 aw This value can be adjusted to any value between 0 0003 and 0 0030 aw Increasing the trigger value causes a subsequent reduction in instrument accuracy and precision but results in a shorter test time This mode is for samples that are slow to equilibrate such as vegetable oils high f...

Page 31: ...M and PM 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 Figure 35 Regional Formatting option Admin Settings Select to create an administrator passw...

Page 32: ...inistrators can add edit or delete users from the User Setup screen The keyboard screen allows for lowercase uppercase and accented letters Figure 37 Figure 37 Keyboard screen NOTE User setup is not required for instrument operation It is in place for users requiring 21 CFR Part 11 compliance or who want to save specific settings Once the administrator and users are set up an Access option will ap...

Page 33: ...or a finished test four continuous or no beeps The audible notification can be turned off Print Mode Select to change the information printed out over the serial port to one of the following options Off Turns off printing out the serial port after a reading has completed Ideal for use with SKALA Hub systems On Turns on basic printing after a reading is completed Reports reading duration in minutes...

Page 34: ...l 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 Figure 42 Data tab View Select to view stored measurements with the most recent measurements at the top of the table Figure 43 Use UP and DOWN to move through the stored data Use LEFT and RIGHT to page quickly through the data ...

Page 35: ...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 Use UP and DOWN to scroll through readings Delete Select this option to delete all data currently stored in the instrument Readings cannot be deleted individually If the information has not been backed up a reminder will appear Figure 45 NOTE D...

Page 36: ...us of the water in a system and is a far better indicator of perishability than moisture content Figure 46 shows how the relative activity of microorganisms lipids and enzymes relate to water activity While other factors such as nutrient availability temperature and pH can affect the relationships water activity is the best single measure of how water affects these processes Figure 46 Water activi...

Page 37: ...es the difference in temperature between the sample and the block It is carefully calibrated to minimize temperature errors but when temperature differences are large water activity can change during testing Best accuracy is therefore obtained when the sample is near chamber temperature Another effect of temperature on water activity occurs when samples are near saturation A sample that is close t...

Page 38: ...is diluted when a solute is added If this diluted water is separated from pure water by a semipermeable membrane water tends to move from the pure water side through the membrane to the side with the added solute If sufficient pressure is applied to the solute water mixture to just stop the flow this pressure is a measure of the osmotic potential of the solution The addition of 1 mol of an ideal s...

Page 39: ...re content is not a driving force for water movement and therefore cannot be used to predict the direction of water movement except in homogeneous materials 3 3 3 MOISTURE CONTENT Moisture content implies a quantitative analysis to determine the total amount of water present in a sample There are two primary methods for determining moisture content loss on drying and Karl Fisher titration Secondar...

Page 40: ...uch more quickly than moisture content This method gives particularly good precision in the center of the isotherm 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 water activity and isothe...

Page 41: ...dards are specially prepared unsaturated salt solutions having a specific molality and water activity value that are accurately measurable The verification standards sent with the initial shipment are very accurate and available from METER Using verification standards to verify accuracy can greatly reduce preparation errors Verification standards come in seven water activity levels 1 000 0 984 0 9...

Page 42: ...on and the 6 00 mol kg NaCl 0 760 aw for the second verification NOTE The AQUALAB TDL needs to warm up for approximately 15 min to make accurate readings 2 Empty a vial of the lower water activity verification standard into a sample cup 3 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 NOTE Make sure the ri...

Page 43: ...e applied Adjust the reading to match the correct verification standard value Section 4 1 2 Measure verification standard Clean sample chamber Reread first standard Go to offset procedure Go to sampling procedure Read second standard Clean sample chamber Repeat process Figure 47 Verification standard flowchart A check indicates AQUALAB TDL verified the standard within specification a cross indicat...

Page 44: ... the whole vial of water activity standard into a sample cup METER recommends using the 6 00 NaCl 0 76 aw Do not adjust for the offset using steam distilled water 7 Ensure the rim and outside of the cup are clean 8 Place the sample cup in the sample chamber 9 Carefully close the lid and move the lever to the READ position 10 Select OK to begin testing NOTE To interrupt the offset procedure return ...

Page 45: ...esting is to be conducted at new temperatures an updated calibration will be needed If a temperature setting that has not been used previously is chosen an error message will appear instructing the user that the calibration needs to be updated This update can be either a linear offset Section 4 1 2 or a multipoint update which requires reading multiple water activity standards NOTE Factory calibra...

Page 46: ...ample cup in the sample chamber 9 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 aw standard be placed in the chamber 12 Repeat steps 6 through 10 using 0 50 0 76 and 0 92 aw standards NOTE To end the multipoint calibration program select ...

Page 47: ...tments to the calibration select OK Select CANCEL to cancel without adjusting the calibration Figure 54 Figure 54 Prompt to adjust calibration 15 To save the new calibration changes select SAVE To cancel the multipoint calibration without saving the new changes select CANCEL Figure 55 Figure 55 Calibration Complete screen Once the multipoint calibration is saved a confirmation screen will appear F...

Page 48: ...AB TDL reads within 0 005 aw at a given temperature 20 Measure a 0 76 aw verification standard If both verification readings are within 0 005 aw the instrument is ready to begin testing If incorrect verification standard readings persist contact Customer Support 4 1 4 RESTORE FACTORY DEFAULTS To restore original calibration settings do the following 1 Navigate to the Configuration tab using MENU 2...

Page 49: ... CANCEL to return to the Calibration menu The instrument will confirm the factory calibration has been restored Figure 60 Figure 60 Confirmation that factory calibration was reset 5 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: ...ion or sample testing For the laser and IR sensor to perform well they must be clean and free from contaminants The instrument should be cleaned if visual inspection indicates the chamber is dirty or as part of the verification process Section 4 1 4 2 1 CLEANING KIT The AQUALAB comes with an AQUALAB Cleaning Kit that contains enough cleaning supplies to clean the instrument for about 1 year The fo...

Page 51: ...zed water f Repeat steps b through d using a new dry KIMWIPES tissue to remove any moisture remaining from the cleaning NOTE Do not reuse tissues 4 Clean the tunable diode laser a Wrap a new KIMWIPES tissue around the end of the spatula and moisten it with cleaning solution b Gently swipe the moistened tissue across the TDL emitter and detector lens once A single swipe is usually sufficient to rem...

Page 52: ...ll not reading samples correctly contact Customer Support 4 3 MAINTENANCE PACKAGES METER offers maintenance and calibration packages to ensure AQUALAB is functioning to its highest standard Table 5 Table 5 Maintenace package options Package Basic Calibration Service As found inspection Available Replace old damaged parts Separate charge per part Instrument cleaning Included Factory calibration Inc...

Page 53: ...and their solutions If the problem is not listed or these solutions do not solve the issue contact Customer Support Table 6 Troubleshooting the AQUALAB TDL Problem Possible Solutions AQUALAB does not turn on Ensure the power cord is securely attached to the back of the instrument and plugged into the power outlet A power surge may have caused a fuse to blow To change the fuses Unplug the power cor...

Page 54: ...ons error message The crystal that runs the firmware is having trouble starting Cycle the power If this message continues to appear the instrument needs to be serviced by METER Section 4 4 Verification is not correct Clean the sample chamber and components Refer to Section 4 2 for detailed cleaning instructions If verification is still not correct verify and adjust for linear offset Section 4 1 2 ...

Page 55: ...mple water activity and the instrument controlling temperature are within the scope of the selected moisture sorption isotherm model Sensors are reading outside of the typical range If after cleaning the instrument and following troubleshooting guidelines there is still a measurement error navigate to the Diagnostics screen If the sensor is reading outside of this range contact Customer Support 4 ...

Page 56: ...umber Description of the problem 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 for details ...

Page 57: ...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: ...ab 30 31 Measurement tab 23 power cord 1 20 RS 232 cable 19 20 sample chamber 20 21 thermopile 21 tunable diode laser 21 USB cable 1 19 Configuration tab 23 30 contamination 37 38 customer support 51 D data annotate 7 delete 31 view 8 9 30 31 Data tab 30 31 date 26 27 diagnostics 29 30 E email address 51 F fax number 51 fuse 2 49 G Gibbs free energy 35 I installation 2 3 isotherm model model offse...

Page 59: ...sample temperature 5 6 sensor 25 serial number 29 30 settings beeps 29 date 26 language 27 mode 25 27 temp eq 24 temperature 24 time 27 specifications 18 19 compliance 19 measurement 18 physical 18 19 power voltage 19 T temp eq 24 temperature 18 19 24 temperature effects 33 34 terms and conditions 52 53 theory moisture content 35 sorption isotherms 35 water activity 32 34 water potential 35 thermo...

Page 60: ...s 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 2020 2021 All Rights Reserved ...

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