Mini-Ligno DX Moisture Meter Calibration for Duraflake FR Flakeboard Particleboard. Test Evaluation Report. Jonathan C. Gates 9Wood, Inc.

Transcription

1 2009 Mini-Ligno DX Moisture Meter Calibration for Duraflake FR Flakeboard Particleboard Test Evaluation Report Jonathan C. Gates 9Wood, Inc. August 2009

2 PARTICLEBOARD ] Abstract: This report analyzes the response of an Electrical Moisture Meter when tested on total of 105 samples of Duraflake FR Flakeboard Particleboard and Standard (non-fr) Particleboard. 15 sample boards of Duraflake FR Particleboard were conditioned in one of six conditioning chambers of various temperatures and relative humidity (ASTM Standard Chamber, a Hot/Dry Chamber, a Hot/Wet Chamber, a Cold Chamber, Outside in ambient air, and Inside in an air conditioned environment). In addition to the 75 samples of Duraflake FR Flakeboard Particleboard, 30 samples of Standard (non-fr) Particleboard were conditioned in two of the six conditioning chambers ( Outside in ambient air as well as Inside in an air conditioned environment). MC measurements were taken from the non-decorative veneer of each sample board with a Mini-Ligno DX moisture meter while on Setting 3 with the short pins installed. Next, calibration of these readings were done using an ASTM D 4442 Oven-Dry method (method A) to determine the linear relationship between the two MC methods. A correction equation and acclimation/equilibrium chart was then created from results. This EMC chart and correction equation will help in determining a fully acclimated panel for installation. Note: This test is a continuation of Calibration of Hand-Held Moisture Meters (Resistance/Capacitance) when used with 9Wood s Particleboard Products. 9Wood, Inc. 0BAbstract: ii

3 Table of Contents Page Number Abstract... ii Introduction... 1 Literature Review Materials and Methodology Figure 1: Picture of Moisture Meter... 3 Figure 2: Picture of Oven... 3 Figure 3: Dimensions of Sample Board... 3 Figure 4: Moisture Meter Placement... 4 Table 1: Temperature and %RH of Conditioning Rooms... 4 Table 2: Sample Board Weights in Conditioning... 5 Figure 5: Picture of Meter in Use... 6 Figure 6: Picture of Weight Scale... 6 Equation 1: Oven-Dry MC Equation... 6 Table 3: Wood Handbook s Table of MC of Wood in Equilibrium... 7 Results and Discussion Table 4: Average %MC of Each Conditioning Chamber and Particleboard Type... 8 Figure 7: Graph of Meter Readings vs. Corresponding Oven-Dry MCs... 8 Table 5: %MC Correction Chart for Duraflake FR Flakeboard Particleboard... 9 Equation 2: Equation used to Calculate Actual %MC in Duraflake FR Flakeboard Particleboard... 9 Table 6: Acclimation/ Equilibrium Chart for Duraflake FR Flakeboard Particleboard... 9 Figure 8: Acclimation/ Equilibrium Graph for Duraflake FR Flakeboard Particleboard Conclusion Literature Cited Appendices Appendix I: Mini-Ligno DX Test Data Appendix II: Oven-Dry Moisture Contents Appendix III: Comparison between "Meter Reading" and "Oven-Dry" moisture content Wood, Inc. 0BAbstract: iii

4 Introduction: Moisture content (MC) has the greatest effect on wood properties. It can vary widely depending on the environment, the species of the wood, and the history of the wood. Effective use of wood and wood-base materials therefore requires efficient and reliable methods of measuring wood moisture (James, 1988). Oven-Drying and Electrical methods are two methods most commonly used to determine MC. The Oven-Drying method is the most universally accepted technique, but isn t always practical. Electrical methods on the other hand use the relationships between MC and measurable electrical properties of wood, such as conductivity (resistivity), or a dielectric constant (capacitance). This method is quick and convenient, but requires the moisture meter to be correctly calibrated to the product. In this report an Electrical method moisture meter (resistance type) was tested against the Oven-Dry method on both Duraflake Fire Retardant (FR) Flakeboard Particleboard and Standard (non- FR) Flakeboard Particleboard with a face and back veneer. The purpose of this project was to create acclimation/equilibrium (EMC) chart for Duraflake FR Flakeboard Particleboard (with a face and back veneer) while using a Mini-Ligno DX moisture meter. The test was also designed to create a correction equation for determining actual percent moisture content (MC) in Duraflake FR Flakeboard Particleboard by examining the difference in measurable MC between Standard (non-fr) Flakeboard Particleboard and Duraflake FR Flakeboard Particleboard. Literature Review: In accordance to building codes and various standards, Flakeboard Duraflake FR Particleboard is treated with fire-retardant chemicals. These chemicals are used to reduce and/or prevent the spread of flame in the case of a fire. Flame-retardant treatment of wood generally improves the products performance during a fire by reducing the amount of flammable volatiles released during fire exposure and/or by reducing the effective heat of combustion. Both results have the effect of reducing the heat release rate (HRR), particularly during the initial stages of fire, and thus consequently reducing the rate of flame spread over the surface. The wood may then self-extinguish when the primary heat source is removed (Wood Handbook, 1999). In the case of particleboard, inorganic salt crystals are generally used in fire-retardancy. Although these chemicals help in the prevention of fire, they pose many problems when determining the MC of the panel. The electrical current is altered by the nature of the inorganic salts when using an Electrical method moisture meter. This false MC can be confusing to the user, and therefore calibration is required to obtain a correct reading. The fire-retardant chemical also poses a problem when using the Oven-Dry method. A panel with a chemical impregnant that is volatile at oven temperatures will evaporate during ovendrying, and the resulting weight loss can be misinterpreted as due to evaporated water. An impregnant that is nonvolatile will remain in the panel and increase the apparent ovendry weight of the wood (James, 1988). The chemical used in Flakeboard Duraflake FR Particleboard is extremely volatile at high temperatures and when exposed to such heat, water is released, thus increasing the apparent MC of the panel. 9Wood, Inc. 1BIntroduction: 1

5 Due to this distortion in meter readings and false ovendry MC in Fire-Retardant panels, it is nearly impossible to obtain the true MC of the panel. Consequently, it is extremely important to calibrate the moisture meters to a given product as well as create an equilibrium/ acclimation chart. By doing this, it can be assured that the panel is at equilibrium with its environment when the target meter reading (from the acclimation chart) and actual meter reading become relatively equivalent. Materials and Methodology: 1. Scope 1.1. Calibrate the Lignomat Mini-Ligno DX (Short Pins installed / on Setting 3 / and taken from the non-decorative veneer) moisture meter using the oven dry method established in ASTM D 4442 (method A) and ASTM D Create acclimation/equilibrium (EMC) chart with the Relative Humidity (RH) and temperature from each conditioning chamber. Assumptions are to be drawn from the Wood Handbooks EMC chart (Table 3-4) Create correction equation from the linear correlation between the Mini-Ligno DX moisture meter and the Oven-Dry MC of Duraflake FR Particleboard as well as the relationship between Oven-Dry MC of Duraflake FR Particleboard and Standard (non-fr) Particleboard. 2. Referenced Documents 2.1. ASTM Standards D 4442 Test Methods for Direct Moisture Content Measurement of Wood and Wood- Based Materials. D 4444 Standard Test Methods for Use and Calibration of Hand-Held Moisture Meters. D 4933 Guide for Moisture Conditioning of Wood and Wood Based Materials. 3. Summary of Test Method samples (15 in each room) of Duraflake FR Flakeboard Particleboard were conditioned in an ASTM Standard Chamber, a Hot/Dry Chamber, a Hot/Wet Chamber, a Cold Chamber, Outside in ambient air, and Inside in an air conditioned environment. 30 samples of Standard (non-fr) Flakeboard Particleboard were divided equally and also conditioned "Outside" in ambient air as well as Inside in an air conditioned environment. MC measurements from the non-decorative veneer of each sample board were taken with a Mini- Ligno DX moisture meter while on Setting 3 with the short pins installed. Next, calibration of these readings were done using an ASTM D 4442 Oven-Dry method (method A) to determine the linear relationship between the two MC methods. A correction equation and acclimation/equilibrium chart was then created from results. 4. Significance and Use 4.1. Refer to ASTM D 4442, D 4444, and D Wood, Inc. 3BMaterials and Methodology: 2

6 5. Apparatus 5.1. Lignomat Mini-Ligno DX Moisture Meter (refer to Figure 1) Refer to ASTM D 4442 & D 4933 for apparatus required for Oven-Dry Method (also shown in Figure 2). Figure 1: Mini-Ligno DX Moisture Meter Figure 2: Oven used in Oven-Dry Method 6. Test Materials 6.1. Wood: Prisms were made from Flakeboard Duraflake FR Particleboard with a face and back veneer Prisms were made from Flakeboard Standard (non-fr) Particleboard with a face and back veneer Sample Size: The specimens were made 4 (101.2mm) in width x 6 (152.4mm) in length x 3/4 (19mm) in thickness (Figure 3). 4 Grain Direction ¾ 6 Figure 3: Dimensions of Sample Board 7. Sampling 7.1. Constants: /4 particleboard with face and back wood veneers Direction of veneer grain in relation to the direction of the moisture meter s pins (parallel correlation) Tested veneer (Plain Sliced Maple) Placement of moisture meter pins on veneer (Figure 4) Variables: Particleboard (Flakeboard Duraflake FR Particleboard and Standard (non-fr) Particleboard. 9Wood, Inc. 3BMaterials and Methodology: 3

7 Conditioning (ASTM, Hot/Dry, Hot/Wet, Cold, Outside/Ambient, Inside/Air Conditioned) replications for each variable/combination were performed on the Duraflake FR particleboard samples (15 in each chamber) of Standard (non-fr) Particleboard were conditioned in two of the six conditioning chambers only ( Outside and Inside ). 8. Testing of Specimen 8.1. A total of 3 readings from the Mini-Ligno DX moisture meter with the short pins installed while on Setting 3 were taken from the non-decorative veneer (Figure 4). Mini Lingo DX Placement Setting 3 Grain Direction Figure 4: Depiction of the Mini-Ligno DX moisture meter and its placement on the panel. This Figure also depicts the grid pattern to be followed The position of the Moisture Meter was strategically placed by following a simple grid pattern on the samples non-decorative veneer (Figure 4). 9. Conditioning 9.1. The Duraflake FR panels were conditioned in an ASTM Chamber, Hot/Dry Chamber, Hot/Wet Chamber, Cold Chamber, Outside in ambient air, and Inside in an air conditioned environment. The Standard (non-fr) panels were conditioned "Outside" and inside only. Particleboard type Relative Conditioning Temperature Humidity Chamber ( C/ F) (%) Duraflake ASTM 20/68 65 Duraflake Hot/Dry 30/86 20 Duraflake Hot/Wet 30/86 90 Duraflake Cold 5/41 80 Duraflake/Standard Outside/Ambient ~19/66 ~64 Duraflake/Standard Inside/Conditioned ~22/71 ~40 Table 1: Temperature and %RH of each conditioning chamber Samples were left to acclimate until a steady weight was reached (Table 2). 9Wood, Inc. 3BMaterials and Methodology: 4

8 Sample Board Weight (grams) in Conditioning Condition Board # Date 25-Sep 26-Sep 27-Sep 28-Sep 29-Sep 30-Sep 1-Oct 2-Oct 3-Oct Inside Sample Board Weight (grams) in Conditioning Condition Board # Date 28-Aug 29-Aug 30-Aug 31-Aug 1-Sep 2-Sep 3-Sep 4-Sep 5-Sep 6-Sep 8-Sep tested ASTM tested tested Hot/Dry Hot/Wet Cold tested Outside tested tested Table 2: Sample board weights during the process of conditioning. 10. Procedure Various Flakeboard Duraflake FR Particleboard and Flakeboard Standard (non-fr) Particleboard panels were obtained from 9Wood s manufacturing facility and cut into designated dimensions (refer to Figure 3) Sample boards were labeled with a number (for reference) and their particleboard core sample boards of the Duraflake FR Particleboard were then placed in one of the six conditioning rooms to acclimate until stable weights were reached. In addition, 30 samples (15 in each chamber) of Standard (non-fr) Particleboard were conditioned in only two of the six conditioning chambers ( Outside and Inside ) (Table 1 & 2) Once acclimation was reached, the boards were transferred to plastic bags to prevent moisture gain/loss. 9Wood, Inc. 3BMaterials and Methodology: 5

9 10.5. One by one, boards will be removed for the bag, weighed, tested with the Mini-Ligno DX moisture meter (Figure 5) and then immediately placed back into another bag. Figure 5: Picture of Mini-Ligno DX as it was applied to the tested panel Once all boards were tested, they were weighed and then placed into the oven to dry for an Oven-Dry moisture content (Figure 6) The sample boards were left to dry for approximately 24 hours. Moisture content was determined using the Oven-Dry method (refer to Equation 1). % Wet Weight Oven Dry Weight Oven Dry Weight 100 Equation 1: Formula used to calculate Oven-Dry MC. Figure 6: Picture of device used to weigh samples The data was then be analyzed to find the difference between Standard (non-fr) Flakeboard Particleboard and Duraflake FR Flakeboard Particleboard. (Standard particleboard results were collected from the test Calibration of Hand-Held Moisture Meters (Resistance/Capacitance) when used with 9Wood s Particleboard Products) The data set from the Mini-Ligno DX moisture meter was graphed and a regression line fitted to the data points. From here, a correlation equation was determined 9Wood, Inc. 3BMaterials and Methodology: 6

10 10.9. An acclimation/equilibrium (EMC) chart was then created with the Relative Humidity (RH) and temperature from each conditioning chamber. Assumptions were drawn from the Wood Handbooks EMC chart (refer to Table 3) A correction equation was created from the linear correlation between the Mini-Ligno DX moisture meter and the Oven-Dry MC of Duraflake FR Particleboard as well as the relationship between Oven-Dry MC of Duraflake FR Particleboard and Standard (non-fr) Particleboard. Table 3: Table 3-4 from Wood Handbook that was used to extrapolate data in equilibrium/ acclimation chart Conclusions were drawn from results 9Wood, Inc. 7

11 Results and Discussion: There was a common difference between Standard non-fr Flakeboard Particleboard and Duraflake FR Flakeboard Particleboard. On average, Duraflake FR Flakeboard Particleboard had an apparent 2.4% higher Oven-Dry MC over Standard Particleboard. Average "Oven-Dry" Moisture Content for Each Conditioning Chamber and Particleboard Type Particleboard Type Conditioning Chamber ASTM Hot/Dry Hot/Wet Cold Outside Inside Standard (non-fr) 9.5% 6.1% 12.8% 11.3% 8.7% 7.5% Duraflake FR 12.2% 8.0% 15.2% 13.7% 11.5% 9.8% Avg. Range 2.7% 1.9% 2.4% 2.4% 2.8% 2.3% 2.4% Table 4: Comparison of average Oven-Dry %MC between Standard (non-fr) Particleboard and Duraflake FR Particleboard after conditioning in each chamber. The Mini-Ligno DX presented high signs of accuracy, precision, and reproducibility. As shown in Figure 7, there was an average correlation of 95% between the Meter Reading and the panel s Oven-Dry moisture content. 18.0% 16.0% 14.0% FR OD %MC = (Meter Reading) R² = Duraflake Oven Dry %MC 12.0% 10.0% 8.0% 6.0% 4.0% 2.0% 0.0% Meter Reading Mini Ligno DX (Short Pin) Setting 3 Linear (Mini Ligno DX (Short Pin) Setting 3) Figure 7: Graph that depicts the Mini-Ligno DX Meter Reading fitted against each panel s Oven-Dry percent moisture content. Note: The complete set of data tables are shown in Appendix I 9Wood, Inc. 4BResults and Discussion: 8

12 A correction chart and equation to find the actual %MC was created by taking the linear regression of the Mini-Ligno DX (Short Pin/ Setting 3/ taken from the non-decorative veneer) and the relationship between Standard (non-fr) Particleboard and Duraflake FR Particleboard (refer to Table 5 and Equation 2). Meter Reading Actual %MC Table 5: Correction Chart for the Mini-Ligno DX (Short Pin / Setting 3 / Taken from non- Decorative face veneer) when tested on Flakeboard s Duraflake FR Particleboard. %.... Equation 2: Meter correction equation used to calculate actual %MC in Duraflake FR Flakeboard Particleboard with a face and back veneer while using the Mini-Ligno DX (Short Pin / Setting 3 / Taken from non-decorative veneer). The previous formula and table will only be helpful if the installer/user desires the true MC of the Duraflake FR Flakeboard Particleboard. However, since the purpose of this test was to create a process of determining a fully acclimated Duraflake FR Particleboard panel, the actual MC is unneeded. All that is necessary is a highly precise Moisture Meter with an equilibrium/ acclimation chart adjusted to the reading from the Meter (refer to Table 6 and Figure 8). This set of equipment assures the installer that the panels are fully acclimated to their environment when a stable Meter Reading close to the acclimation/equilibrium chart s value is met. Temperature Moisture Content (%) at various relative humidity values ( F) 20% 40% 65% 80% 90% Table 6: Acclimation/Equilibrium chart for Duraflake FR Flakeboard Particleboard when using a Mini-Ligno DX (Short Pin / Setting 3 / Taken from non-decorative veneer) moisture meter. 9Wood, Inc. 4BResults and Discussion: 9

13 Mini Ligno DX Meter Reading % 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Relative Humidity 40 Deg. F 70 Deg. F 100 Deg. F Figure 8: Acclimation/Equilibrium graph for Duraflake FR Flakeboard Particleboard when using a Mini-Lingo DX (Short Pin / Setting 3 / Taken from non-decorative veneer) moisture meter. 9Wood, Inc. 4BResults and Discussion: 10

14 Conclusion: This study demonstrates that the Mini-Ligno DX (Short Pin / Setting 3 / Taken from non- Decorative veneer) moisture meter is a great tool for estimating the MC of laminated Duraflake FR particleboard. With the correct procedure, panel acclimation can be easily predicted with the Mini- Ligno DX moisture meter. To obtain desirable results when measuring panel EMC, the following steps must be preformed: 1. Place the panels in the installation environment. Position them with spaces to allow free air flow around all surfaces of the panel. Stabilize the installation environment to a steady temperature and relative humidity within acceptable parameters (refer to Architectural Woodwork Standards; published by AWI). Measure and record the relative humidity and temperature of the room. 2. Use the equilibrium/acclimation chart or graph to estimate the target Mini-Ligno DX meter reading for the given temperature and relative humidity. 3. Three readings from the back of the panel (non decorative side) are to be average from the Mini-Ligno DX moisture meter while on Setting 3 with the short pins installed. 4. Repeat step 3 over a few days until a steady meter reading has been collected. The reading should correspond to the chart s meter reading (from step 2). If not, let the panels acclimate for a longer period of time. Note this step could take a while before completed. a. Acclimation may take only a few days if the initial readings are close to the target. It may take a week or more for the panels to make a large change in moisture content. 5. Once fully acclimated, the panels are ready to be installed. Premature installation could lead to panel distortion (warp) due to dimensional changes induced by moisture loss or gain. 9Wood, Inc. 5BConclusion: 11

15 Literature Cited: Forest Products Laboratory Wood handbook Wood as an engineering material. Gen. Tech. Rep. FPL GTR 113. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 463 p. James, William L. Electric moisture meters for wood. Gen. Tech. Rep. FPL-GTR-6. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory; p. 9Wood, Inc. 6BLiterature Cited: 12

16 9WOOD, INC. Appendices: Copy of Test Data and Graphs Test Evaluation Report Jonathan C. Gates August, Wood, Inc. 7BAppendices: 13

17 Appendix I: Mini-Ligno DX (Short Pin / Setting 3 / Taken from non-decorative veneer) Test Data 9Wood, Inc. 7BAppendices: 14

18 9Wood, Inc. 7BAppendices: 15

19 Appendix II: Oven-Dry Moisture Contents: 9Wood, Inc. 7BAppendices: 16

20 9Wood, Inc. 7BAppendices: 17

21 Appendix III: Comparison between "Meter Reading" and "Oven-Dry" moisture content 9Wood, Inc. 7BAppendices: 18

22 PARTICLEBOARD ] 9Wood, Inc. 7BAppendices: 19