1、T 240 om-12 OFFICIAL TEST METHOD 1981 REVISED 1988 REVISED 1993 REVISED 2002 REVISED 2007 REVISED 2012 2012 TAPPI The information and data contained in this document were prepared by a technical committee of the Association. The committee and the Association assume no liability or responsibility in
2、connection with the use of such information or data, including but not limited to any liability under patent, copyright, or trade secret laws. The user is responsible for determining that this document is the most recent edition published. Approved by the Standard Specific Interest Group for this Te
3、st Method TAPPI CAUTION: This Test Method may include safety precautions which are believed to be appropriate at the time of publication of the method. The intent of these is to alert the user of the method to safety issues related to such use. The user is responsible for determining that the safety
4、 precautions are complete and are appropriate to their use of the method, and for ensuring that suitable safety practices have not changed since publication of the method. This method may require the use, disposal, or both, of chemicals which may present serious health hazards to humans. Procedures
5、for the handling of such substances are set forth on Material Safety Data Sheets which must be developed by all manufacturers and importers of potentially hazardous chemicals and maintained by all distributors of potentially hazardous chemicals. Prior to the use of this method, the user must determi
6、ne whether any of the chemicals to be used or disposed of are potentially hazardous and, if so, must follow strictly the procedures specified by both the manufacturer, as well as local, state, and federal authorities for safe use and disposal of these chemicals. Consistency (concentration) of pulp s
7、uspensions 1. Scope 1.1 This method describes the measurement of pulp consistency (concentration) of aqueous fiber suspensions. 1.2 The method applies to most pulps sampled from different process points in a pulp or paper mill. 1.3 The method is applicable to pulps with up to 25% consistency. 2. Sum
8、mary A known weight of pulp suspension is filtered in a Bchner funnel. Fibers and other suspended matter are retained on an oven dried, pre-weighed filter paper. After drying to constant weight at 105 3C, the oven-dry weight of the retained matter is determined and calculated as the percentage of or
9、iginal pulp suspension weight. 3. Significance Determination of pulp consistency is the starting point for the quantitative analysis of many other pulp characteristics. Furthermore, it provides the basis for mass balance and yield evaluation in a pulp and paper mill. 4. Definitions 4.1 Pulp suspensi
10、on: aqueous fiber suspension that may contain fillers, additives, contaminants, and other non-fibrous components. 4.2 Pulp consistency: the weight percentage of oven-dry matter accounting for the total weight of the pulp suspension. 5. Apparatus 5.1 Sampling cup, 200 mL, wide mouth with a smooth lip
11、 5.2 Beaker, 600 mL T 240 om-12 Consistency (concentration) of pulp suspensions / 2 5.3 Dilution container, 10-40 L 5.4 Mechanical stirrer for mixing 5.5 Balances, 40-kg capacity, accurate to 50 g; 2-kg capacity, accurate to 0.1 g; 100-g capacity, accurate to 0.01 g 5.6 Bchner funnel, 150-mm diamete
12、r, and filtration flask, 2000 mL 5.7 Filter paper, ashless, with coarse pore sizes, 150 mm in diameter. 5.8 Drying oven, with forced-air circulation, set at 105 3C 5.9 Hot-plate type dryer, set at 150 5C 6. Sampling 6.1 When sampling according to the following procedure, always take the sample at th
13、e point of greatest agitation. For good sampling, a high degree of agitation is necessary as the uniformity of the pulp suspension is proportional to the degree of agitation. The accuracy of the method is very dependent on the sampling procedure. 6.2 When sampling from a mill stock line, chest, valv
14、e, or similar area, the number, frequency, and sampling technique should be representative of the process and source being sampled. When the representative sample of pulp suspension is obtained, store the sample in a cool area away from direct sunlight until the laboratory procedure is performed on
15、the composite sample. 7. Procedure 7.1 While rigorously mixing the sample, quickly withdraw three consecutive portions with a sampling cup and transfer the contents into a tared beaker. The total weight of the pulp suspension should be approximately 400 g, or a minimum of 1 gram oven-dry pulp. Clean
16、 the outside surface of the beaker if pulp has dripped on it. Weigh the pulp to the nearest 0.1 g. 7.2 If the pulp consistency is 1% or lower, go directly to the next step. If the pulp consistency is higher than 1%, dilution is required. Add the pulp suspension and a known amount of water to a dilut
17、ion container. The amount of water added should be sufficient to dilute the pulp to less than 1% consistency. Mix the diluted pulp thoroughly. Then go back to 7.1 to take an aliquot from the diluted pulp. 7.3 Place a pre-weighed filter paper in the Bchner funnel and moisten it with water. Apply suct
18、ion, then pour the pulp suspension into the Bchner funnel. Rinse the beaker with a small amount of water and add the rinsing to the funnel. 7.4 If the filtrate is cloudy, re-filter the filtrate until it becomes clear. 7.5 Remove the fiber pad along with the filter paper. Collect any fibers that stuc
19、k to the inner surface of the funnel. Dry the fiber pad and filter paper in an oven with forced-air circulation at 105 3C for at least 2 hr to constant weight. Cool the pad in a desiccator. Weigh the pad to the nearest 0.01 g. If two successive readings, taken 30 minutes apart, do not differ by more
20、 0.01 g, constant weight has been reached. NOTE 1: For practical purposes, drying with a hot-plate type dryer to constant weight is often sufficiently accurate and it takes much less drying time. NOTE 2: For pulps containing 10% or more filler, accuracy is affected due to filler loss. In addition, f
21、iltering is prolonged. In the case that filler content is so high that it is impossible to complete filtering within a reasonable amount of time, retention aids can be added. Alternatively, consistency can be measured with evaporation instead of filtering. 8. Calculation 8.1 For pulp suspension with
22、 1% consistency or less, 100%, =gfwC , in which, C = pulp consistency, % w = weight of the oven-dry pad and filter paper, g f = weight of the oven-dry filter paper, g g = weight of the original pulp, g 3 / Consistency (concentration) of pulp suspensions T 240 om-12 8.2 For pulp suspension with highe
23、r than 1% consistency, 100%, +=gdgafwC , in which, C = pulp consistency, % w = weight of the oven-dry pad and filter paper, g f = weight of the oven-dry filter paper, g a = weight of aliquot of diluted pulp, g g = weight of the original pulp, g d = weight of the dilution water, g 9. Report Report th
24、e average pulp consistency of two determinations to three significant figures. 10. Precision 10.1 The following precision data is in accordance with the definition in TAPPI T 1200 “Interlaboratory Evaluation of Test Methods to Determine TAPPI Repeatability and Reproducibility.” 10.2 Repeatability =1
25、0% 10.3 Reproducibility. Reproducibility for this method is impractical to determine because of the difficulty in proper sampling for a round robin. 11. Keywords Pulp, Consistency, Concentration, Fibers, Dispersions 12. Additional information 12.1 Effective date of issue: April 24, 2012. 12.2 This m
26、ethod was first published in 1967 as a Suggested Method and became an Official Method in 1975; it was revised in 1981 and 1993. Minor editorial revisions explaining the reproducibility and the related methods were made in the 2012 version. 12.3 Related methods: ISO 4119 “Determination of Stock Conce
27、ntration,” International Organization for Standardization, Genve, Switzerland; PAPTAC D-16 “Consistency of Stocks,” Pulp and Paper Technical Association of Canada, Montreal, Canada; SCAN C 17 “Stock Concentration,” Scandinavian Pulp, Paper, and Board Testing Committee, Stockholm, Sweden. Your comments and suggestions on this procedure are earnestly requested and should be sent to the TAPPI Standards Department. g
