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Related Manuals for Nelson-Jameson 3230026
Summary of Contents for Nelson-Jameson 3230026
- Page 1 WATER ACTIVITY METER 1.800.826.8302 • nelsonjameson.com • sales@nelsonjameson.com...
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Page 2: Table Of Contents
18425-00 11.1.2020 TABLE OF CONTENTS 1. Introduction ....................1 2. Operation ....................2 2.1 Setup ......................2 2.1.1 Sample Preparation ................. 3 2.1.2 Taking a Measurement ..............4 3. System ......................9 3.1 Specifications .................... 9 3.2 Components .................... 10 3.3 Theory ...................... - Page 3 4.3 Repairs ....................25 4.4 Troubleshooting ..................25 4.5 Customer Support..................26 Reference ....................... 27 Index ......................... 28...
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Page 5: Introduction
WATER ACTIVITY METER 1. INTRODUCTION Thank you for choosing the Nelson-Jameson Handheld Water Activity Meter. This water activity meter is designed to be a simple, rapid, and portable system for water activity measurement to ensure product safety. It is easy to use, durable, and requires little maintenance. -
Page 6: Operation
If a sample is accidentally left in the chamber for an extended period of time, be sure to check the calibration when the instrument is used next. Table 1 Preparation Nelson-Jameson water activity meter unit Material to sample Plastic sample cup... -
Page 7: Sample Preparation
WATER ACTIVITY METER Table 1 Preparation (continued) Sample Placement Installation Place the water activity meter over the sample cup as described. 2.1.1 SAMPLE PREPARATION Carefully prepare samples to get the best readings possible. Always use clean sampling practices to ensure accurate and repeatable readings. Follow the steps below when preparing samples. -
Page 8: Taking A Measurement
OPERATION Thermometer icon Figure 1 Thermometer icon on screen The instrument beeps when the sample temperature is too high, indicating there is a danger of condensing water in the sample chamber and on the sensor. If this warning appears while sampling, remove the water activity meter, place the cup lid on the sample, and wait until the sample has reached ambient temperature before attempting to read again. - Page 9 WATER ACTIVITY METER Place the prepared sample cup onto a level surface. Sample cup Figure 3 Sample cup placement Place the opened water activity meter onto the prepared sample cup. The cup fits under the sensor into a recess in the bottom of the water activity meter. Table top Table top Figure 4 Handheld water activity meter placement on sample cup...
- Page 10 OPERATION button Figure 5 I button Press the I button a second time to begin the water activity measurement. The LCD display resets to 0.00 a NOTE: Pressing the I button any time during a measurement restarts the water activity measurement. Once the measurement process has been started, the water activity meter begins to display water activity measurements as well as temperature after 5 s, updating the display every second thereafter.
- Page 11 After 5 min, the instrument displays the final water activity and beeps 5 times. The sunburst disappears when the water activity reading is finished. NOTE: Nelson-Jameson recommends recording the reading value before proceeding. At this point, either restart the measurement by pressing I button again or end the measurement procedure.
- Page 12 OPERATION When finished taking readings, close the instrument. With one hand holding the case near the LCD, pull down on the plastic sensor cover tab with the other hand and rotate until it snaps into the closed position covering the sensors. Snap cover CLOSED position tab in place...
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Page 13: System
WATER ACTIVITY METER 3. SYSTEM This section describes the specifications, components, and theory of the water activity meter. 3.1 SPECIFICATIONS MEASUREMENT SPECIFICATIONS Water Activity 0.00-1.00 a Range Resolution 0.01 Accuracy ±0.02 Sample Temperature Resolution 0.1 °C ±0.2 °C Accuracy Read Time 5 min PHYSICAL SPECIFICATIONS Dimensions... -
Page 14: Components
Manufactured under ISO 9001:2015 EM ISO/IEC 17050:2010 (CE Mark) 3.2 COMPONENTS Figure 10 shows the features on the top and Figure 11 shows hardware on the bottom of the water activity meter. button Sample button Figure 10 Nelson-Jameson handheld water activity meter features... -
Page 15: Theory
Thermopile sensor Figure 11 Nelson-Jameson handheld water activity meter hardware The water activity meter uses a capacitance humidity sensor to measure the water activity of a sample. The sensor is suspended behind the sensor filter and uses a special polymer material sandwiched between two microporous electrodes to sense humidity changes. -
Page 16: Water Activity
SYSTEM However, moisture content alone is not a reliable indicator for predicting microbial responses and chemical reactions in materials. The limitations of moisture content measurement are attributed to differences in the intensity that water associates with other components. 3.3.2 WATER ACTIVITY Water activity (a ) is a measurement of the energy status of the water in a system. - Page 17 WATER ACTIVITY METER headspace by monitoring the change in electrical capacitance. When the water activity of the sample and the relative humidity of the air are in equilibrium, the measurement of the headspace humidity gives the water activity of the sample. In addition to equilibrium between the liquid phase water and the vapor phase, the internal equilibrium of the sample is important.
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Page 18: Water Potential
SYSTEM stop the flow, this pressure is a measure of the osmotic potential of the solution. Addition of 1 mol of an ideal solute to 1 kg of water produces an osmotic pressure of 22.4 atm. This lowers the water activity of the solution from 1.0 to 0.98 a . - Page 19 WATER ACTIVITY METER While the sorption isotherm is often used to infer water activity from moisture content, one could easily go the other direction and infer the moisture content from water activity. This is particularly attractive because water activity can be measured much more quickly than water content.
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Page 20: Service
Nelson-Jameson recommends verification daily, once per shift, or before each use. Nelson- Jameson also recommends annual factory calibration to maintain optimal performance. -
Page 21: Verify Calibration
WATER ACTIVITY METER 4.1.2 VERIFY CALIBRATION Use the following steps to verify the water activity meter calibration. NOTE: An error code of 9.99 at any time during the process indicates that the sensor has failed and that the instrument needs to be serviced. Refer to Section 4.4 for shipping instructions. - Page 22 SERVICE Adjust the calibration. Scroll to the proper screen for calibration adjustment. Press the I button to adjust the correct value. Each time the I button is pressed, the value in the corner changes by an increment of 0.01. Store the new calibration value. Scroll to the proper screen for calibration adjustment.
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Page 23: Maintenance
0.92 Adjust Adjust Figure 14 Calibration routine flowchart 4.2 MAINTENANCE The water activity meter may be returned to Nelson-Jameson for maintenance in the following areas: • system inspection • parts replacement • instrument cleaning Replacement parts can also be ordered from Nelson-Jameson. Contact Customer Support for more information. -
Page 24: Cleaning
SERVICE 4.2.1 CLEANING The accuracy of the water activity meter depends on keeping the instrument clean. Dust and sample debris can contaminate the sampling chamber, and must be regularly cleaned. To clean the instrument, carefully follow the instructions in this section. The water activity meter comes with the compact cleaning kit that contains all the materials needed to clean the instrument for about a year. -
Page 25: Filter Replacement
WATER ACTIVITY METER NOTE: Do NOT reuse KIMWIPES strips or tissues. Thermopile sensor lens Figure 15 Thermopile sensor lens 4.2.2 FILTER REPLACEMENT The porous white humidity sensor filter may periodically need to be replaced if it becomes dirty. To remove the sensor filter use a knife or needle point to gently pry up the edge of the filter (Figure 16). -
Page 26: Battery Replacement
SERVICE Sensor filter Figure 16 Filter removal CAUTION DO NOT touch the capacitance humidity sensor because it is extremely fragile. Capacitance humidity sensor Figure 17 Capacitance humidity sensor 4.2.3 BATTERY REPLACEMENT The water activity meter uses two lithium-ion battery cells that should last for several years. If the battery charge is low, a low-battery indicator icon (Figure 18) will persistently appear in the lower right corner of the screen. - Page 27 WATER ACTIVITY METER Low battery icon Figure 18 Low battery icon Follow steps 1 through 6 below to replace battery. Remove the water activity meter bottom by unscrewing the two screws. Screw locations Figure 19 Battery compartment screws Separate the stainless steel top and elastomer (which contains the batteries) from the white plastic bottom.
- Page 28 SERVICE WATER ACTIVITY METER top Elastomer Figure 20 Separate top and elastomer Remove the old lithium-ion batteries. Replace with new CR1632 or equivalent 3 V lithium coin cells. Make sure to orient the batteries so positive (+) contact is facing down into the elastomer pocket.
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Page 29: Repairs
An extra fee may be charged for rush work. Contact Customer Support for an estimated repair cost. All water activity meter units returning to Nelson-Jameson 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. -
Page 30: Customer Support
4.5 CUSTOMER SUPPORT Nelson-Jameson's friendly, professional Customer Service Representatives are available 7 am to 7 pm CST Monday through Friday. Whether it's a question about product selection, order status, shipping, or billing, you will receive a prompt, complete answer. -
Page 31: Reference
WATER ACTIVITY METER REFERENCE Labuza, Ted P., K. Acott, S. R. TatiNl, R. Y. Lee, Jv Flink, and W. McCall. "Water activity determination: a collaborative study of different methods." Journal of Food Science 41, no. 4 (1976): 910-917. -
Page 32: Index
10 calibration mode screen 17 operating environment 10 scroll to desired calibration mode 17 operating temperature 10 turn on Nelson-Jameson water activity power requirement 10 meter 5 email address 26 enzymes. See theory; water activity equilibrium. See theory; water activity calibration 16–18... - Page 33 WATER ACTIVITY METER humidity related to water activity 11 turn Nelson-Jameson water activity meter OFF 8 LiCl. See calibration, standards lipids. See water activity, lipids turn Nelson-Jameson water activity liquid phase water. See water activity, meter ON 5 liquid phase water open sample chamber lid.
- Page 34 INDEX sampling cosmetics 11 environment 3 enzymes 12 inserting sample 5–6 equilibrium location 2 water activity and relative humidity 11 multicomponent 3, 13 factors in determining preparation 3 pressure effects 13 saturated sample. See temperature, wet Gibbs free energy 14 sample, cautions homogenous 3 sensor, capacitance humidity 11...
- Page 35 WATER ACTIVITY METER osmotic effects 13 perishability 11. See also theory regulations 11–13 stability diagram 12 water potential Gibbs free energy 14 homogeneous 3 thermodynamic property 14...
- Page 36 18426-00 11.1.2020 Nelson-Jameson, Inc. 3200 S. Central Ave, P.O. Box 647 Marshfield, MI 54449 T: +1.800-826-8302 F: +1.800.472.0840 E: sales@nelsonjameson.com W: nelsonjameson.com KIMWIPES is a registered trademark of Kimberly-Clark Worldwide, Inc. Used with permission. ® © 2020 All Rights Reserved.