1、T 281 sp-12 STANDARD PRACTICE 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 connection with the use of such informatio
2、n 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 Test Method TAPPI CAUTION: This Test Method
3、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 precautions are complete and are appropri
4、ate 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 for the handling of such substances are se
5、t 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 determine whether any of the chemicals to be used
6、 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. Open drum washer mat sampling technique 1. Scope This practice provides a means
7、 to collect pulp mat and liquor samples from open drum washers. 2. Significance Samples collected according to this practice are used to determine drum washer operating parameters, such as, the consistency of the pulp mat (1), and the dissolved solids or chemical oxygen demand (COD) content of the l
8、iquor. 3. Definitions 3.1 Consistency is the amount of oven dry fiber, expressed as a percent of total sample weight. Consistency is determined by TAPPI T 240 “Consistency (Concentration) of Pulp Suspensions.” 3.2 Dissolved solids are the washable, or soluble solids contained in the liquor portion o
9、f the sample. This does not include bound or fixed sodium adsorbed by the pulp. Dissolved solids are determined by TAPPI T 650 “Solids Content of Black Liquor” (2). 3.3 COD is determined by a recognized industry standard (e.g., ASTM D1252 - 06 “Standard Test Methods for Chemical Oxygen Demand (Dichr
10、omate Oxygen Demand) of Water” or PAPTEC Standard H.3 (2006) “Chemical Oxygen Demand“ (3,4). 3.4 The term “liquor” refers to the water plus soluble solids. 4. Apparatus 4.1 A wooden paddle or scraper, approximately 125-150 mm (5-6 in.) wide with a tapered lip, (see Figure 1), used to lift/scrape the
11、 pulp mat off the drum face. 4.2 Containers for liquor samples. 4.2.1 Sealable plastic bags for the mat samples. T 281 sp-12 Open drum washer mat sampling technique / 2 4.2.2 Plastic screw-cap containers, 50200mL minimum, for the liquor and low consistency stock samples. 5. Safety precautions CAUTIO
12、N. Collecting samples from brown stock washers involves handling hot, caustic pulp and liquor. Appropriate protective clothing and safety equipment should be used. There is a potential for severe burns. Operators collecting samples are to do so in such a fashion as to not place body parts (hands, ar
13、ms) inside the hood of the brownstock washer. Breaking the plane of an opening into a confined space with any part of your body may be considered to be a violation of OSHA Confined Space Entry standards. Fig. 1. Suggested paddle design (dimensions are in millimeters). 3 / Open drum washer mat sampli
14、ng technique T 281 sp-12 6. Sampling 6.1 Take multiple samples at 3 to 4 locations along the length of the drum at intervals no greater than 1.2 m. This sampling procedure should be repeated over time (hrs days weeks). 6.2 Avoid samples from the very ends and center of the washer drum. These are lik
15、ely to vary significantly from the machine average. 6.3 Collect samples in air tight containers or plastic bags and label them appropriately to identify the sample. 6.4 Samples should be processed as soon as possible for best results. If not possible, be consistent in storage time. 6.5 Samples may b
16、e evaluated individually, to give a cross machine profile, or combined into a single composite sample for an average result. 7. Procedure 7.1 Low Consistency Stock Samples: 7.1.1 Collect samples in a scoop or sample bottles described in 4.2.2 from the washer inlet. The sample should be collected wit
17、h a smooth dipping action avoiding areas of stagnation or high turbulence. If transferring samples between containers, mix (by stirring or shaking) to insure uniformity of the sample. 7.2 Pulp Mat Samples: 7.2.1 Using the paddle described in 4.1, obtain a pulp mat sample from the discharge side of t
18、he washer drum being careful to avoid repulper. Collect the sample with a scraping/lifting motion taking care not to damage the drum face but ensuring that the sample is the full thickness of the pulp mat. This procedure should yield a rough mat sample approximately 125-150 mm (5-6 in.) square. 7.2.
19、2 Break off the outer edges of the rough sample to obtain a final sample approximately 75 mm (3 in.) square. Place this final sample in a labeled plastic bag as described in 4.2.1, seal the bag and set aside for laboratory testing. 7.2.3 Collect an additional sample (or samples) in accordance to 7.2
20、.1 and prepare a 75-mm (3-in.) square (as described in 7.2.1.). Take the 75-mm (3-in.) sample and immediately squeeze the liquor from it, using a gloved hand or a mechanical press, into a sample bottle as described in 4.2.2 to obtain a 25-50 mL liquor sample. Tightly cap the labeled sample bottle an
21、d set aside for laboratory testing. 7.3 Liquor Samples: 7.3.1 Using a bucket or labeled sample bottles described in 4.2.2, obtain samples from the appropriate liquor lines. Allow the sample stream to flow freely prior to sample collection until the line and sample tap are well flushed. 8. Calculatio
22、ns None required. 9. Report None required; however, the following information will be helpful in evaluating the washers performance: Drum speed RPM Vacuum kPa Vat temperature C Production rate air-dried or oven-dried tons (or metric tones) per day Washing shower flow PM Drum diameter mDrum width m T
23、 281 sp-12 Open drum washer mat sampling technique / 4 10. Precision Since this is a Standard Practice, a precision statement is not required. However, it is imperative that all samples be collected and handled in a uniform and consistent manner to ensure statistical accuracy. 11. Keywords Consisten
24、cy, Dissolved solids, Drums, Washer, COD 12. Additional information 12.1 Effective date of issue: April 24, 2012. 12.2 Revisions in this 2012 edition include: (1) clarification of the definition of pulp consistency in Section 3.; (2) addition of standard test methods for measuring chemical oxygen de
25、mand (COD) in Section 3; (3) Inclusion of Figure 1 in Section 4, which was missing; and (4) addition of safety caution statement in Section 5 regarding OSHA Confined Space Entry Standards to a brownstock washer hood. Literature cited 1. TAPPI T 240 “Consistency (Concentration of Pulp Suspensions).”
26、2. TAPPI T 650 “Solids Content of Bleach Liquor.” 3. ASTM D1252 - 06 “Standard Test Methods for Chemical Oxygen Demand (Dichromate Oxygen Demand) of Water” 4. PAPTEC Standard H.3 (2006) “Chemical Oxygen Demand.” Your comments and suggestions on this procedure are earnestly requested and should be sent to the TAPPI Standards Deparment. g
