1、Designation: E 2408 04Standard Test Method forRelative Extensional Viscosity of Agricultural Spray TankMixes1This standard is issued under the fixed designation E 2408; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the relativeextensional viscosity or Screen Factor (SF) of dilute agricul-
3、tural spray mixes.1.2 The test can be used for tank mixes containing dis-solved, emulsified or dispersed materials, or mixtures.1.3 Results may be affected by the quality of the water used.Make-up water quality should therefore be specified in thepresentation of results.1.4 Proper safety and hygiene
4、 precautions must be takenwhen working with pesticide formulations to prevent skin oreye contact, vapor inhalation, and environmental contamina-tion. Read and follow all handling instructions for the specificformulation and conduct the test in accordance with goodlaboratory practice.NOTE 1References
5、 to the development of extensional viscosity fromdissolved polymers, extensional viscosity effects on the droplet sizedistribution of sprays, and measurements of screen factor on recirculatedspray mixes containing polymers are available2,3.1.5 This standard does not purport to address all of thesafe
6、ty concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:4D 1193 Specifications for Reagen
7、t WaterE 609 Terminology Relating to PesticidesE 1116 Test Method for the Emulsification Characteristicsof Pesticide Emulsifiable Concentrates2.2 CIPAC Documents:CIPAC Monograph 1 (Instructions for the preparation ofhard water)CIPAC Method MT 18.1.1 to 18.1.7 (Instructions for thepreparation of stan
8、dard waters)3. Terminology3.1 Definitions:3.1.1 screen factor, (SF)the ratio of the flow time of a testfluid (tp) to the flow time of water (tw) through the screenviscometer apparatus.3.1.2 extensional viscosity, (E)a measure of the resistanceof a fluid to distortion by a stretching force.4. Signifi
9、cance and Use4.1 Extensional viscosity is a measure of the resistance of aliquid to stretching forces, such as those occurring during thedisruption of liquid films and the formation of sprays used inagriculture and other purposes including painting operations ormetal working. This method for measure
10、ment of a ScreenFactor, gives a relative value for extensional viscosity, whichmay be used:4.1.1 To compare the potential for drift control of differentpolymers.4.1.2 To compare the relative extensional viscosity compo-nent of different spray tank mixtures.4.1.3 To determine the extent of breakdown
11、of polymersolutions used as drift control additives during the recirculationof the solutions through pumps and screens.4.1.4 To use as a parameter in the Spray Drift Task ForceModels for droplet size prediction.4.2 It should also be noted that many drift control polymersare irreversibly destroyed du
12、ring the recirculation of spraymixes by pumping with high shear pumps such as gear orcentrifugal pumps. It is advisable to subject the test mixture tosimilar pumping regimes to simulate practical conditionsbefore carrying out the extensional viscosity test. Measure-ments of extensional viscosity are
13、 the only presently known1This test method is under the jurisdiction of ASTM Committee E35 onPesticides and Alternative Control Agents and is the direct responsibility ofSubcommittee E35.22 on Pesticide Formulations and Delivery Systems.Current edition approved Oct. 1, 2004. Published November 2004.
14、2Dexter, R. W.,Measurements of Extensional Viscosity of Polymer Solutions andits Effect on Atomization from a Spray Nozzle,” Atomization and Sprays, 6, 1996,pp. 167-1913Zhu, H., Dexter, R. W., Fox, R. D., Reichard, D. L., Brazee, R. D., and Okzan,H. E.,“Droplet Size and Viscosity Effects in Recircul
15、ated Polymer Spray Solutions,”J. Agric. Engr. Res., 67, 1997, pp. 35-454For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe AST
16、M website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.method of determining the extent of this breakdown propertiesof dilute polymer solutions.4.3 This method is intended to produce a relative value forextensional viscosity. The
17、purpose of the method is to comparethe extensional viscosity produced by different polymer typesor concentrations of polymer in spray tank mixes.5. Apparatus5.1 List of Materials for Construction of Screen Viscometer:5.1.1 Item 1Fluorinated plastic14 in. (0.635 cm) straightunion, reference SKU-II4,
18、P#D1O77019. Norton PerformancePlastics, 150 Dey Road, Wayne, New Jersey, 07470, USA.5.1.2 Item 2Cut five (5)14 in. diameter discs (see 5.2)from 100 mesh (150 m aperture) USA Standard Testing Sieve,ASTM E 11 specification, stainless steel plain weave screen, soas to fit tightly into the14 in. plastic
19、 union.5.1.3 Item 3Glass 25 mL pipette, VWR catalog #7102(1999) or equivalent. External diameter of the tube below thebulb of the pipette = 0.82 cm. Cut off the lower part of thepipette at a point 2.5 cm below the bulb. Round off the sharpedges of the tube with a flame.5.1.4 Item 4Silicone rubber tu
20、bing, flexible, for use as asleeve to join a glass tube (Item 5) to the lower end of thepipette (Item 3).5.1.5 Item 5Glass tube, cut froma2mLpipette, Kimax#37000, or equivalent (American Scientific catalog #P4140-2).Dimensions of tube are: length = 3 cm; outside diameter = 0.62cm. Round off the shar
21、p ends of the tube in a flame.NOTE 2Appropriate safety precautions should be taken when using anopen flame for rounding the ends of the glass tubes.5.2 Assembly of Screen ViscometerRefer to Fig. 1, whichshows the arrangement of the separate items of equipment, andFig. 2, which shows the placement of
22、 the screen pack in theplastic union.5.2.1 Push the five stainless screen discs, one at a time, intothe14 in. (0.635 cm) plastic union. Push each screen down tothe central lug in the union, using a piece of14 in. glass tubing.Ensure that the last of the 5 screens fits tightly into the plastictube to
23、 keep the pack of screens well compacted and fixed inplace.5.2.2 Push the silicone rubber sleeve (Item 4) on to thelower end of the pipette tube (Item 3). Leave approximately 0.8cm of the silicone tube projecting beyond the glass.5.2.3 Push the short glass tube (Item 5) into the plastic unionfirmly
24、and press down on the pack of screens. Screw on the endcap of the union to retain the position of the screen pack.Ensure that the Teflon cone supplied with the union is fittedproperly, to provide a leak tight seal. About 0.6 cm of the glasstube should protrude from the end cap of the union.5.2.4 Pus
25、h together the glass tube protruding from the endcap, into the silicone rubber sleeve attached to the pipette.Check the alignment of the pipette and screen pack forstraightness.5.3 Other Accessories Required:5.3.1 Two 500 mL beakers.5.3.2 A stand and clamp to hold the pipette firmly in avertical pos
26、ition.5.3.3 A stopwatch, reading to 0.01 s.5.3.4 A 200 mesh USA Standard Testing (75 m aperture)stainless steel sieve, 4 in. diameter.5.3.5 A pipette bulb, or preferably, a low vacuum suctiondevice (see 7.2.2).6. Test Materials6.1 Deionized Water, filtered through a 200 mesh (75 maperture) stainless
27、 steel screen, for use in rinsing the apparatusand as a standard fluid for calibrating the screen pack.6.2 Test Fluid(s), as required to be tested.FIG. 1 Diagram of ApparatusE24080427. Procedure7.1 Preparation of Test Fluids for use in Screen Viscometer:7.1.1 Dilute the formulation in the appropriat
28、e standardwater to the desired spray concentration. Pass approximately500 mL of the liquid so prepared through a 200 mesh USAStandard stainless steel sieve, to remove poorly dispersedaggregates or gels. The test can be run with as little as 200 mLof the test fluid. The temperature of the fluid shoul
29、d be kept atstandard temperature, preferably in a constant temperatureroom.NOTE 3Dilute solutions of high molecular weight polymers oftenrequire prolonged dissolution to allow for complete swelling and disso-lution, especially if provided as solids. Note also that excessive stirring orshearing by pu
30、mping can cause degradation of the polymer moleculesresulting in a decrease in molecular weight and viscosity. If the solution isdrawn up into the screen viscometer too rapidly, it may be degraded. It hasbeen found useful to use a vacuum device that provides a low andconsistent suction to the pipett
31、e.7.2 Calibration of Screen Viscometer:NOTE 4Water is used as the calibration fluid.7.2.1 Place 400 mL of deionized water in a 500 mL beakerand adjust to the required temperature. (A temperature of 23 to25C has been used, but any temperature at which the screenfactor is required may be used. The cal
32、ibrating fluid (water)and the test fluid must be run at the same temperature).7.2.2 Lower the screen viscometer assembly into the water,clamp the pipette in a vertical position, and draw up water intothe pipette through the screen pack, by applying vacuum to thetop of the pipette. Draw the water up
33、to a point about 2 in.above the upper timing mark.7.2.3 Raise the pipette tip above the surface of the liquidabout 2 cm, and fix in position using the clamp, so that theliquid will fall freely from the pipette in air during draining.Then allow the water to run out of the pipette freely undergravity.
34、 Start the stopwatch as the meniscus passes the uppertiming mark, and stop the watch when the meniscus passes thetop edge of the silicone rubber sleeve. The efflux time is shortand practice may be needed to obtain consistent results. Recordthe efflux time.7.2.4 Repeat the measurement a total of 5 ti
35、mes, andaverage the efflux times. This is the efflux time for water (tw).Record the temperature of the room and fluid.7.3 Testing Spray Fluids:7.3.1 Completely drain the screen viscometer after calibra-tion with deionized water.7.3.2 Draw up the test fluid (as in 7.2.2) and record theefflux time for
36、 the fluid. Repeat the measurements a total of 5times.7.3.3 Record the average time as the efflux time of the fluid(tp).7.3.4 If a second test fluid is to be run, then the screenviscometer should be thoroughly rinsed with filtered deionizedwater and drained between tests.NOTE 5If inconsistent result
37、s are obtained it is probably due totrapped air. Air bubbles can be released by tapping the pipette bulb andscreen pack.8. Report8.1 Report the following information:8.1.1 Average efflux time for water, tw.8.1.2 Average efflux time for the test fluid, tp.8.1.3 Calculate the average value of Screen F
38、actor:Screen Factor SF!5 (1)average efflux time of the test fluidaverage efflux time for water at specified temperature5tptwFIG. 2 Diagram of ApparatusE24080438.1.4 In all cases the water quality should be specified, inparticular the concentration and chemistry of the dissolvedsolids content of the
39、liquid. Any unusual treatment of the sprayliquid, for example pretreatment by pumping, should bereported.9. Precision and Bias9.1 PrecisionThe reproducibility of this test method asdetermined by statistical analysis of results obtained fromseveral laboratories in a round robin was as follows, averag
40、edover single operators:For water flow times (tw),Standard deviation of tw= 0.7 to 4 % for a single operatorFor polymer solution flow times (tp),Standard deviation of tp= 0.8 to 3 % for a single operatorFor Screen Factor values (SF),Standard deviation of SF = 1.5 to 6 % for a single operator9.1.1 Re
41、peatability is expressed in terms of the standarddeviation from the mean in several tests. The existing data fromthe round robin indicate that the standard deviation of ScreenFactor for measurements of several different fluids conductedby all operators in aggregate is approximately 15 %.NOTE 6In the
42、 round robin procedure adopted, each operator wasrequired to construct his own apparatus, so that some differences in resultsfrom different operators would be expected, increasing the standarddeviation between operators.9.2 BiasThere exist other methods for the determinationof extensional viscosity.
43、 Extensional viscosity is dependentupon the strain rate for most polymer solutions, an differentmethods of measurement may give different extensional vis-cosity values, because of variations in the strain rate applied inthe equipment. This method may provide values for ScreenFactor that do not agree
44、 with the results of extensionalviscosity from other methods. This method operates at rela-tively low extensional strain rates and may therefore be biasedtowards low extensional strains, so that the values of exten-sional viscosity may be relatively low, compared with, forexample, the Rheometrics RF
45、X instrument. However, themethod gives good comparisons between fluids and is moresensitive than other methods, especially at low polymer con-centrations. Reports of the use of this method and its relevanceto spray droplet size control are available (see Section 2,Referenced Documents).ASTM Internat
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49、ds, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).E2408044
