1、Designation: F1738 10Standard Test Method forDetermination of Deposition of Aerially Applied Oil SpillDispersants1This standard is issued under the fixed designation F1738; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 the surface of thegr
3、ound 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 can be used to confirm
4、 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 F1413 covers design, PracticeF1460 covers calibrat
5、ion, Test Method F1738 covers deposi-tion, and Guide F1737 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 method since they are a fun
6、ction 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 asstandard. No other units of measurement are included in thisstan
7、dard.1.6 This standard does not 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. Referen
8、ced Documents2.1 ASTM Standards:2F1413 Guide for Oil Spill Dispersant Application Equip-ment: Boom and Nozzle SystemsF1460 Practice for Calibrating Oil Spill Dispersant Appli-cation Equipment Boom and Nozzle SystemsF1737 Guide for Use of Oil Spill Dispersant ApplicationEquipment During Spill Respons
9、e: Boom and NozzleSystems3. 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 p
10、er unit area by the delivery 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 i
11、thas been released from the 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 de
12、velopment of new systems and 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 Di
13、spersant deposition and droplet size data can be usedas a technical basis for the optimization of dispersant applica-tion equipment and its use.1This test method is under the jurisdiction of ASTM Committee F20 onHazardous Substances and Oil Spill Response and is the direct responsibility ofSubcommit
14、tee F20.13 on Treatment.Current edition approved April 1, 2010. Published April 2010. Originallyapproved in 1996. Last previous edition approved in 2007 as F1738 96(2007).DOI: 10.1520/F1738-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at se
15、rviceastm.org. 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. Apparatus and Materials4.1 The basic concept is to
16、 provide a collection surface onwhich the aerially applied material is deposited. The amount ofmaterial and the deposition pattern and its droplet size can bemeasured using this surface. Several systems and methodshave been developed, and each has its own advantages anddisadvantages.4.2 These measur
17、ements require a large, flat open area (suchas a field 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 shou
18、ld be conducted under low-wind conditions in order 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
19、 All tests are to be conducted with the flight path 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 ex
20、perimentalprogram.4.5 It is common practice to use 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 co
21、ncentrations atthe 0.1 % level or less.4.6 The area 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
22、, especially precipitation that occursafter the spray 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
23、 be used, such as the following:5.1.1 Glass Petri 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
24、be about twenty dishes placedacross the flight path 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 dependi
25、ng on the spray system being tested.Each sampling 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 dispers
26、ant, water, or rough handling. The samplingdishes 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, su
27、ch as methanol or hexane, to collect the depositedmaterial. 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
28、be taken to ensure that the same dilution factors 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 anyu
29、nits required, such as litres/hectare (U.S. gal/acre), 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 o
30、ftroughs, connected end-to-end, are used to cover 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
31、, butthis system has the advantage of sampling the 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.
32、3 String MeasurementAnother method uses a cord orstring 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, a
33、ndthus the needed data are obtained. Since the cross 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 color
34、metrictechnique. This method measures the relative 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 s
35、wath of the spray. From this, spraypatterns can be 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 an
36、y indicationof the drop size or drop-size distribution. 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 d
37、rops on asurface and then measure the area of the drop. The surface mustF1738 102be 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 di
38、stribution of various drop sizes. It represents asingle parameter description of a spray-pattern droplet sizedistribution and is statistically based. Therefore, VMD cannotbe used to compute the terminal velocity of a drop or itsmomentum. It is the momentum that is critical for the dispers-ant, since
39、 this determines the probability of the droplet 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, th
40、e flux ofdroplets are so dense that they overlap, 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
41、 Ciba-Geigy. There are two productsthat are 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 we
42、ll as droplet size. Special paper that is 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
43、the drop area on the material. This is done 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
44、examined in order to achieve good statistics. 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 t
45、o be demonstrated to be successful in field 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 inform
46、ation that need to bederived from these tests. 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 fromt
47、he volume of material deposited on the Petri 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 ofspra
48、y deposited as shown in the left of the graph. 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. Theeffec
49、ts of the wing tank are not large enough to 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
