1、Designation: F 316 03Standard Test Methods forPore Size Characteristics of Membrane Filters by BubblePoint and Mean Flow Pore Test1This standard is issued under the fixed designation F 316; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, 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 These test methods cover the determination of two ofthe pore size properties of membrane filters w
3、ith maximumpore sizes from 0.1 to 15.0 m.1.2 Test Method A presents a test method for measuring themaximum limiting pore diameter of nonfibrous membranes.The limiting diameter is the diameter of a circle having thesame area as the smallest section of a given pore (Fig. 1).1.3 Test Method B measures
4、the relative abundance of aspecified pore size in a membrane, defined in terms of thelimiting diameter.1.4 The analyst should be aware that adequate collaborativedata for bias statements as required by Practice D 2777 is notprovided. See the precision and bias section for details.1.5 This standard m
5、ay involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the user of this standard toestablish appropriate safety and health practices and deter-mine the applicability
6、of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 1129 Terminology Relating to Water2D 1193 Specification for Reagent Water2D 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D19 on Water2E 128 Test Method for Maximum Pore Diame
7、ter and Per-meability of Rigid Porous Filters for Laboratory Use33. Terminology3.1 DefinitionsFor definitions of other terms used in thesetest methods, refer to Terminology D 1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 pore sizecapillary equivalent pore diameter.3.2.2 limiting pore
8、 diameterdiameter of a circle havingthe same area as the smallest section of a given pore.TEST METHOD AMAXIMUM PORE SIZE4. Summary of Test Method4.1 The bubble point test for maximum pore size is per-formed by prewetting the filter, increasing the pressure of gasupstream of the filter at a predeterm
9、ined rate and watching forgas bubbles downstream to indicate the passage of gas throughthe maximum diameter filter pores.4.2 The pressure required to blow the first continuousbubbles detectable by their rise through a layer of liquidcovering the filter is called the 9bubble point9, and is used tocal
10、culate maximum pore size.5. Significance and Use5.1 This test method may be used to:5.1.1 Determine the maximum pore size of a filter,5.1.2 Compare the maximum pore sizes of several filters,and5.1.3 Determine the effect of various processes such asfiltration, coating, or autoclaving on the maximum p
11、ore size ofa membrane.5.2 Membrane filters have discrete pores from one side tothe other of the membrane, similar to capillary, tubes. Thebubble point test is based on the principle that a wetting liquidis held in these capillary pores by capillary attraction andsurface tension, and the minimum pres
12、sure required to forceliquid from these pores is a function of pore diameter. The1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee D19.08 on Membranes andIon Exchange Materials.Current edition approved Jan. 10, 2003. Publis
13、hed April 2003. Originallypublished as F 316 70. Last previous edition F 316 86.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 14.04.FIG. 1 Examples of Limiting Diameters1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959
14、, United States.pressure at which a steady stream of bubbles appears in this testis the bubble point pressure. The bubble point test is significantnot only for indicating maximum pore size, but may alsoindicate a damaged membrane, ineffective seals, or a systemleak.5.3 The results of this test metho
15、d should not be used as thesole factor to describe the limiting size for retention ofparticulate contaminants from fluids. The effective pore sizecalculated from this test method is based on the premise ofcapillary pores having circular cross sections, and does notrefer to actual particle size reten
16、tion. See Test Method E 128for additional information.6. Apparatus6.1 Filter Holder, as shown in Fig. 2, consisting of a baseA,a locking ring B, O-ring seal C, support disk D, and gas inletE. The support disk shall be 2-ply construction, consisting of a100 by 100 mesh or finer screen and a perforate
17、d metal platefor rigidity. The diameter of the test filter may be either 25 or47 mm, as appropriate to the holder being used for the test.6.2 Manifold, as shown in Fig. 3, a micrometric flow controlvalve capable of providing a linear rise in pressure and a gasballast of at least 16 000-cm3capacity.N
18、OTE 1For less accurate determinations, the simplified apparatusshown in Fig. 4 may be used.6.3 Pressure Gages (and mercury manometer if required),covering the range of pressures needed for the pore sizes underinvestigation (see Table 1).6.4 Metal Punch, used to cut a suitable size filter from thetes
19、t sheet to fit the test filter holder.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Societywhere suc
20、h specifications are available.4Other grades may beused provided it is first ascertained that the reagent is ofsufficient high purity to permit its use without lessening theaccuracy of the determination.7.2 Water, conforming to Specification D 1193, Type IV orhigher purity.7.3 Denatured Alcohol.7.4
21、Petroleum Distillate, with surface tension of 30dynes/cm at 25C.7.5 Mineral Oil, such as USP liquid petrolatum heavy, withsurface tension of 34.7 dynes/cm at 25C.7.6 1,1.2-trichloro-l,2,2-trifluoroethane (Freon TFt), avail-able from commercial chemical supply houses.7.7 Clean Gas Pressure Source, wi
22、th regulation (filtered airor nitrogen).NOTE 2Table 1 lists the nominal surface tension of these liquids at25C. Table 2 lists the simplified maximum pore size formulas based onthese values, where the liquid completely wets the membrane.8. Procedure8.1 Wet the test membrane completely by floating it
23、on apool of the liquid. Use a vacuum chamber to assist in wettingthe filter, if needed.8.2 Place the wet membrane in the filter holder.8.3 Close the filter holder and apply slight gas pressure toeliminate possible liquid back flow.8.4 Cover the perforated metal plate with 2 to 3 mm of testliquid.8.5
24、 Increase the gas pressure slowly. Record the lowestpressure at which a steady stream of bubbles rises from thecentral area of the liquid reservoir.NOTE 3Faulty sealing may cause erroneous bubbling from the sealingedge of the liquid reservoir. Be sure to record the bubble point pressurewith bubbles
25、from the central area of the reservoir (see Fig. 5).9. Calculation9.1 If the test liquid is known to wet the membranecompletely, calculate the maximum pore size from the follow-ing equation:d 5 Cg/p (1)where:d = limiting diameter, m,g = surface tension, mN/m, (dynes/cm),p = pressure, Pa or cm Hg, an
26、dC = constant, 2860 when p is in Pa, 2.15 when p is in cmHg, and 0.415 when p is in psi units.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Stan
27、dards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 2 Filter HolderF316032NOTE 4The fluid must completely wet the membrane filter with thecontact angle being zero. If the
28、 contact angle is greater than zero, thecalculated effective pore size will be larger than the actual effective poresize rating.10. Reporting Results10.1 Record the minimum pressure for gas passage asindicated by continuous bubbles. Record the maximum poresize calculated, along with identification o
29、f the membranetested and the liquid used.TEST METHOD BDETERMINATION OF PORESIZE DISTRIBUTION11. Summary of Test Method11.1 A fluid-wet filter will pass air when the applied airpressure exceeds the capillary attraction of the fluid in thepores. Smaller pores will exhibit similar behavior at higherpre
30、ssures. The relationship between pore size and pressure hasbeen established, as indicated in Table 2.11.2 By comparing the gas flow rates of both a wet and dryfilter at the same pressures, the percentage of the flow passingthrough the filter pores larger than or equal to the specified sizemay be cal
31、culated from the pressure-size relationship. Byincreasing pressure in small steps, it is possible to determinethe flow contribution of very small pore size increments bydifference.11.3 To determine the mean flow pore size, a pressure issought at which the wet filter flow is one half of the dry filte
32、rflow.12. Significance and Use12.1 This test method may be used to:Key Quantity Component1 1 Filter2 1 Pressure regulator3 1 Pressure gage4 1 Valve shutoff, manual5 1 Valve, flow control, manual6 4 Valve, solenoid, nc7 1 Air ballast8 1 Quick disconnect fitting9 2 Open filter holder, 47 mm10 1 Valve,
33、 3-way, manual11 1 Test gage, 0-0.3 kPa (0-30 psig)12 1 Test gage, 0-0.8 kPa (0-100 psig)13 1 Exhaust silencer14 2 Pilot light, red, elec.15 1 Switch, spdt, elec.FIG. 3 Manifold for Bubble Point TestingFIG. 4 Test Setup (Simplified)F31603312.1.1 Determine the pore size distribution of a membranefilt
34、er,12.1.2 Determine the mean flow pore size of a membranefilter,12.1.3 Determine the effect of processes such as steriliza-tion, upon the pore size distribution,12.1.4 Measure the maximum pore size of a membranefilter, and12.1.5 Determine the gas flow rate of a filter, and thereby itsgas flow capabi
35、lity.13. Apparatus13.1 Clean Gas Pressure Source, with regulation (filteredair or nitrogen).13.2 Pressure Gage (or set of gages), covering the neces-sary pressure range for the pore sizes under study. (See Table1.)13.3 Closed Filter Holder, (see Fig. 6).NOTE 5Two l-in. (25-mm) filter holders, instea
36、d of one holder,eliminate the task of cleaning the filter holder after a fluid-wet air flowdetermination. A two-position gas valve to switch the gas pressure fromdry to wet holders may be used (see Fig. 7).13.4 Set of Rotameters, covering the range from 0 to 100L/min.13.5 Test Tube and Capillary Tub
37、e, to serve for detection ofthe bubble point.13.6 In-Line Fluid Trap, to protect the rotameters from thefluid.13.7 Appropriate Fittings, Hose, Connectors, Piping,toassemble apparatus as shown in Figs. 6 and 7.13.8 x-y Recorder, to assist in graphing results of mean flowpore test.14. Reagents14.1 Min
38、eral Oil, such as USP liquid petrolatum heavy.15. Procedure for One Holder ( Fig. 6)15.1 Place a dry filter sample disk in the filter holder.15.2 Close the holder and apply gas pressure in increments.TABLE 1 Pressure Ranges RequiredFluid UsedPore Size Range to be Investigated (Alternative psi)$1m $0
39、.5 m $0.1 m $0.05 mSurface Tension,dynes/cmat 25CWater 0 to 155 cm Hg(0 to 30 psi)0 to 310 cm Hg(0 to 60 psi)0 to 775 cm Hg(0 to 150 psi)0 to 3100 cm Hg(0 to 600 psi)72.0Petroleum distillate 0 to 65 cm Hg(0 to 15 psi)0 to 130 cm Hg(0 to 25 psi)0 to 325 cm Hg(0 to 65 psi)0 to 1300 cm Hg(0 to 250 psi)
40、30.0Denatured alcohol 0 to 50 cm Hg(0 to 10 psi)0 to 100 cm Hg(0 to 20 psi)0 to 250 cm Hg(0 to 50 psi)0 to 1000 cm Hg(0 to 200 psi)22.3Mineral oil 0 to 75 cm Hg(0 to 15 psi)0 to 150 cm Hg(0 to 30 psi)0 to 305 cm Hg(0 to 75 psi)0 to 1500 cm Hg(0 to 300 psi)34.7Freon TFT 0to40cmHg(0 to 8 psi)0to80cmHg
41、(0 to 16 psi)0 to 200 cm Hg(0 to 40 psi)0 to 800 cm Hg(0 to 100 psi)17.3TABLE 2 Calculation of Maximum Pore Size from Bubble Point Pressure,Ad = Cl/PNOTERefer to Appendix X1 for derivation of maximum pore size formula.Fluid UsedPressure Units of Bubble Pointcm Hg psi PaWater 155/Bubble Point 30.0/Bu
42、bble Point 2.06 3 105/Bubble PointPetroleum distillate 64.6/Bubble Point 12.5/Bubble Point 8.58 3 104/Bubble PointDenatured alcohol 47.75/Bubble Point 9.25/Bubble Point 6.38 3 104/Bubble PointMineral oil 74.5/Bubble Point 14.4/Bubble Point 9.92 3 104/Bubble PointFreon TFT 37.2/Bubble Point 7.2/Bubbl
43、e Point 4.95 3 104/Bubble PointAExampleA certain filter was observed to have a bubble point of 41.0 psi with petroleum distillate:Size (m) = 12.5/41.0 psiTherefore, maximum pore size = 0.305 m.FIG. 5 Examples of Erroneous Bubble PointsF31603415.3 Plot gas flow versus gas pressure over the intendedra
44、nge of use. (Estimate from pore size-pressure formula, seeTable 1.)15.4 Reduce gas pressure and remove the filter from theholder.15.5 Completely wet the filter in mineral oil, replace the wetfilter in the holder, and apply a slight pressure, checking to seethat a tight seal exists.15.6 Increase pres
45、sure gradually and record the pressure ofthe first gas flow detected by the capillary tube tip immersed inthe test tube half-filled with mineral oil.15.7 Change to rotameters and plot the fluid-wet filter gasflow versus pressure on the same coordinates as for the plotmade in accordance with 15.3.15.
46、8 Reduce the pressure, remove the filter, and clean theholder for the next test.16. Procedure for Two Holders ( Fig. 7)16.1 Place a dry filter in the holder to be used exclusivelyfor dry filters.16.2 Wet a filter of the same type and lot as the filter usedin 16.1, in mineral oil and place it in a ho
47、lder to be usedexclusively for wet filters.16.3 Apply gas pressure to the dry filter and plot gas flowversus gas pressure.16.4 Change the two position valve to apply gas pressure tothe wet filter holder and record the first gas flow as detected bythe capillary tube as the bubble point. Switch to rot
48、ameters andplot fluid-wet gas flow versus gas pressure.17. Calculation of Mean Flow Pore Size17.1 Record the minimum pressure for gas passage (bubblepoint pressure). Calculate the maximum pore size from theformula in 9.1 and correlation data in Table 2.17.2 Using the graph from 16.3, draw the line (
49、or curve)corresponding to one half the dry gas-flow rate of the testedfilter. Find the intersection of this (one-half dry-flow) line andthe wet flow line (or curve), as shown in Fig. 8. Determine thepressure coordinate of the intersection and substitute into thepressure-pore size formula. (See Table 2 for mineral oil.)FIG. 6 Setup for One HolderFIG. 7 Setup for Two HoldersF31603518. Calculation of Pore Size Frequency18.1 Select the limits of the pore size range being evaluated.Substitute the limits individually into the pore-size versuspressure formula and
