1、Designation: F 1738 96 (Reapproved 2007)Standard Test Method forDetermination of Deposition of Aerially Applied Oil SpillDispersants1This standard is issued under the fixed designation F 1738; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、revision, the year of last 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 measurement of the depo-sition of an aerially applied dispersant on
3、 the surface of theground or water. The test method of obtaining these measure-ments is described, and the analysis of the results, in terms ofdispersant use, is considered. There are a number of techniquesthat have been developed, and this test method outlines theirapplication. These measurements c
4、an be used to confirm orverify the specifications of a given equipment set, its properfunctioning, and use.1.2 This test method is applicable to systems used withhelicopters or airplanes.1.3 This test method is one of four related to dispersantapplication systems. Guide F 1413 covers design, Practic
5、eF 1460 covers calibration, Test Method F 1738 covers deposi-tion, and Guide F 1737 covers the use of the systems. Famil-iarity with all four standards is recommended.1.4 There are some exposure and occupational health con-cerns regarding the methods described. These are not discussedin this test me
6、thod since they are a function of dispersantformulation. Anyone undertaking such experiments shouldconsult the occupational health experts of the dispersantmanufacturer regarding the precautions to be used.1.5 The values stated in SI units are to be regarded as thestandard.1.6 This standard does not
7、 purport to address all of thesafety 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
8、:2F 1413 Guide for Oil Spill Dispersant Application Equip-ment: Boom and Nozzle SystemsF 1460 Practice for Calibrating Oil Spill Dispersant Appli-cation Equipment Boom and Nozzle SystemsF 1737 Guide for Use of Oil Spill Dispersant ApplicationEquipment During Spill Response: Boom and NozzleSystems3.
9、Significance and Use3.1 The deposition of an aerially applied dispersant isdefined as the amount of an aerially applied dispersant thatcontacts the surface; whereas, application dosage (frequentlyreferred to as application rate) is the amount of material that isreleased per unit area by the delivery
10、 system. The units ofdeposition are litres per hectare or U.S. gallons per acre. Thedeposition may differ from the application dosage (volume ofmaterial per unit area) for many reasons, such as, the effects ofwind on the spray and the evaporation of the dispersant after ithas been released from the
11、aircraft.3.2 This test method describes the measurement of theability of a spray system to deposit a dispersant on oil. It is notintended that this test method be used at the time of a spill.These techniques are intended to determine the equipmentperformance during the development of new systems and
12、 afterthe repair or significant modification of a system.3.3 The data obtained from the use of this test method canbe directly related to the deposition of dispersant on an oilslick, and thus can serve to determine both the dispersantdeposition and the droplet size.3.4 Dispersant deposition and drop
13、let size data can be usedas a technical basis for the optimization of dispersant applica-tion equipment and its use.4. Apparatus and Materials4.1 The basic concept is to provide a collection surface onwhich the aerially applied material is deposited. The amount ofmaterial and the deposition pattern
14、and its droplet size can bemeasured using this surface. Several systems and methodshave been developed, and each has its own advantages anddisadvantages.1This test method is under the jurisdiction of ASTM Committee F20 onHazardous Substances and Oil Spill Response and is the direct responsibility of
15、Subcommittee F20.13 on Treatment.Current edition approved April 1, 2007. Published May 2007. Originallyapproved in 1996. Last previous edition approved in 1999 as F 1738 96 (1999).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org
16、. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.2 These measurements require a large, flat open area (suchas a f
17、ield or an airport) which is suitable for low-level flyingand maneuvering. The location should be away from humanhabitations or environmentally sensitive areas in order tominimize problems due to noise and drifting spray.4.3 These field programs should be conducted under low-wind conditions in order
18、 to minimize drift. Near-surfaceturbulence due to thermal gradients or atmospheric instabilitycan contribute to a variation in the results. These measurementscannot be carried out in the presence of precipitation or inheavy concentrations of dust.4.4 All tests are to be conducted with the flight pat
19、h in anupwind direction. The upwind direction is chosen to simplifythe interpretation of the data and to conform with typical fieldpractice. It may be necessary to alter the flight path slightly forchanges in wind direction during the course of an experimentalprogram.4.5 It is common practice to use
20、 a dye, soluble in thedispersant, which will assist in the detection of the dispersantby the analysis system. Oil Red B and Rhodamine WP havebeen used at concentrations of 0.1 to 2.0 %. The sensitivity ofcurrent detection systems allows the use of concentrations atthe 0.1 % level or less.4.6 The are
21、a used will become covered with dispersantspray, and it is suggested that the area not be used foragricultural purposes at least until any evidence of the dispers-ant or dye is no longer observable. The length of time dependson the weather conditions, especially precipitation that occursafter the sp
22、ray program has been completed.5. Deposition Measurement Methods5.1 These techniques involve the use of a collecting surfaceof known area and the measurement of the amount andcharacter of the dispersant deposited on this area. A variety ofsystems may be used, such as the following:5.1.1 Glass Petri
23、Dishes or Similar ContainersFlat dishesof known area are placed in a line perpendicular to the flightpath, and extending over a distance 25 % greater than theexpected swath width. Dishes of a diameter of 120 to 140 mmare typically used. There should be about twenty dishes placedacross the flight pat
24、h in order to have an adequate number ofsampling points. In a typical experimental setup, the distancebetween sampling dishes should be greater than one metre andless than three metres. This criteria may require more or lessthan twenty dishes depending on the spray system being tested.Each sampling
25、dish should be identified by a unique label,indicating its place on the sampling line and the number of thespray pass. The marking should be made in such a fashion thatit will not be removed by the dispersant, the material used todissolve the dispersant, water, or rough handling. The samplingdishes
26、are kept covered until just before the spray run to reducethe possibility of contamination. The placement, uncovering,and retrieval of these dishes is labor intensive. After the sprayrun, the dishes are collected and washed with a suitablesolvent, such as methanol or hexane, to collect the deposited
27、material. The amount of dye present can be determined byusing a colorimeter sensitive to the dye used. The system mustbe calibrated using a sample of the dyed dispersant and solventmixture for that experimental pass. For these measurements,care must be taken to ensure that the same dilution factors
28、areused for both the calibration and material from the samplingdishes, since the measurement instruments are only linear overabout an order of magnitude of concentration. From these setsof data, the amount of material deposited on the surface in anyunits required, such as litres/hectare (U.S. gal/ac
29、re), can becalculated.5.1.2 Metal TroughsA variation of the sampling dish is aV-shaped metal trough, divided into sections and placedperpendicular to the flight path. Each section is about twometres long with a cross section of about 6 cm. A number oftroughs, connected end-to-end, are used to cover
30、a length ofabout 25 % greater than the total spray width.After a spray run,the troughs are washed with a solvent, such as methanol orhexane, and the eluent from each section is collected foranalysis. The concept is similar to that of the glass dishes, butthis system has the advantage of sampling the
31、 total spraywidth, and providing an average dose over the discrete section.One major advantage of the troughs is that they remain in placeduring a number of experimental runs, thus reducing the timebetween runs. This allows for more runs per day.5.1.3 String MeasurementAnother method uses a cord ors
32、tring that is either stretched across the width of the spray or issupported on a series of stands. Except for very narrow-widthapplication systems, the string is supported about every twometres by a stand. The dispersant is collected by the string, andthus the needed data are obtained. Since the cro
33、ss section of thestring is much smaller than that of the Petri dish or trough,more dye may be needed in the sprayed dispersant. The stringis then allowed to dry. The amount of material that the stringcollected is determined by a fluorometric or colormetrictechnique. This method measures the relative
34、 deposition only,and not the absolute deposition.5.1.4 Data DeterminationThe data collected from thesetypes of measurements is the same in character. The amount ofdispersant that reaches the ground is measured as a function ofthe position along the swath of the spray. From this, spraypatterns can be
35、 determined and plotted. Data gathered usingdishes and the metal troughs can be used to compute the actualdeposition.6. Drop-Size Determination6.1 While the techniques of Section 5 provide an accuratemeasurement of the deposition, they do not give any indicationof the drop size or drop-size distribu
36、tion. Since this is animportant parameter in the proper use of dispersants, drop-sizemeasurements are also required in order to characterize adispersant application system. The basic principle of mostdrop-size measurements is to capture the falling drops on asurface and then measure the area of the
37、drop. The surface mustbe calibrated so that the conversion factor from drop volume tosurface drop diameter is known.6.1.1 The analysis of such drop sizes is expressed as avolume median diameter (VMD). The VMD is the effectivediameter of a distribution of various drop sizes. It represents asingle par
38、ameter description of a spray-pattern droplet sizedistribution and is statistically based. Therefore, VMD cannotbe used to compute the terminal velocity of a drop or itsF 1738 96 (2007)2momentum. It is the momentum that is critical for the dispers-ant, since this determines the probability of the dr
39、oplet pen-etrating the slick.6.2 Most techniques developed for pesticide drop-size mea-surements fail since the deposition for dispersants is severalorders of magnitude greater than those used for pesticides.When these techniques are used for dispersants, the flux ofdroplets are so dense that they o
40、verlap, and thus, individualparticles cannot be measured.6.3 There are a number of methods that have been used inthe measurement of drop size. Most use paper as the absorbingmaterial. One common system uses specially coated cards suchas those manufactured by Ciba-Geigy. There are two productsthat ar
41、e typically used: a water-sensitive paper, that is yellow incolor and stains blue when exposed to water and the other iswhite which stains blue when exposed to organic materials.These materials can be used to measure spray distributions andswath widths as well as droplet size. Special paper that is
42、usedby the printing industry for color reproduction can be used forthe same purpose.Another system collects the drops on rolls ofpaper tape. All such methods require the calibration of thedetection medium in terms of the relationship between dropletsize and the drop area on the material. This is don
43、e in thelaboratory.6.4 Drop size can be determined by measuring the size ofthe projected image of the drop. Counting the drops anddetermining the drop size can be done either manually or usingelectronic image analysis systems. A large number of dropsmust be examined in order to achieve good statisti
44、cs. Manualcounting is a time-consuming and tedious process. Modernelectronic image analysis systems are expensive and takeconsiderable time and skill in order to produce high-qualityresults.6.5 The use of recently developed laser-scattering systemshave yet to be demonstrated to be successful in fiel
45、d measure-ments. The sampling volume of most of these systems is quitesmall, and the density of drops that traverse this volume issmall. Thus, there are problems in obtaining good statisticswith such a system.7. Data Analysis7.1 There are two types of information that need to bederived from these te
46、sts. The first is the distribution of materialacross the swath width and the second is the determination ofthe range of the drop sizes.7.2 The determination of the distribution of material acrossthe swath width can be done by extracting the information fromthe volume of material deposited on the Pet
47、ri dishes, in theV-troughs, or on the string. The final output is a graph such asis shown in Fig. 1. These data are easy to interpret. There wasa wing tank on the starboard side of the aircraft whichproduced some turbulence and thus reduced the amount ofspray deposited as shown in the left of the gr
48、aph. The graphslopes slightly upward indicating a slight crosswind movingfrom the left to the right. The random peaks on the right arecaused by the slight crosswind. The pattern is good, and withthe exception of the wing tank, there are no problems. Theeffects of the wing tank are not large enough t
49、o exclude the useof the plane for dispersant application with the existing spraysystem. Larger nozzles in the area of the wing tank couldproduce an even flatter pattern. The errors in this sort ofmeasurement are about 10 %. This is not a significant error.7.3 The second is the droplet size distribution. The graph inFig. 2 shows a typical droplet-size distribution. While thisgraph can be used directly to determine the droplet sizedistribution, the most common representation of these data aresummarized in a single parameter, the VMD. This can becalculated very simply, directly from
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