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定价： 156元 / 折扣价： 133 元 加购物车

定价： 156元 / 折扣价： 133 元 加购物车

定价： 260元 / 折扣价： 221 元 加购物车

定价： 156元 / 折扣价： 133 元 加购物车

定价： 156元 / 折扣价： 133 元 加购物车

定价： 156元 / 折扣价： 133 元 加购物车

定价： 156元 / 折扣价： 133 元 加购物车

1. Scope This part of ISO 14269 specifies a uniform test method for determining performance levels of operator enclosure panel-type air filters. It is applicable to tractors and self-propelled machines for agriculture and forestry when equipped with an

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This specification provides standard dimensional requirements for glass filtering flasks suitable for general laboratory use. Glass filter flasks shall be in the following types: Type I, Type II (Class 1 and Class 2), and Type III (Class 1, Class 2, and Class 3). Flasks shall be made of the specified borosilicate glass and shall conform to the prescribed maximum residual thermal stress. The general appearance of the flasks are illustrated. The design for (1) conical flasks including bottom concavity and bottom heel radius, (2) neck finish, and (3) side-arm are specified. Filtering flasks shall conform to the prescribed requirements for (1) capacity; (2) dimensions such as body outside diameter, overall height, rubber stopper size, bottom and heel wall thickness, and base/heel radius; and (4) pressure resistance. Each flask shall be permanently marked with the name or known trademark of the manufacturer and the nominal capacity. There shall be an area on one side of the flask for marking with a pencil.1.1 This specification provides standard dimensional requirements for glass filtering flasks suitable for general laboratory use.1.2 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 This test method is intended for use in evaluating the cleanliness of middle distillate fuels, and biodiesel and biodiesel blends for specifications and quality control purposes.5.2 The filter media specified in the three procedures are all suitable for the materials in the . Specifications calling up this test method should state the procedure required.5.3 A change in filtration performance after storage or pretreatment can be indicative of changes of fuel condition.5.4 The filterability of fuels varies depending on filter porosity and structure and therefore results from this test method might not correlate with full-scale filtration.5.5 Causes of poor filterability in industrial/refinery filters include fuel degradation products, contaminants (including water) picked up during storage or transfer, effects due to temperature or composition for bio fuels, incompatibility of commingled fuels, or interaction of the fuel with the filter media. Any of these could correlate with orifice or filter system plugging, or both.5.6 The results of the FBT test can range from 1 with a fuel with very good filterability, to over 100 for a fuel with poor filterability. The selection of a single FBT number to define a pass or fail criteria is not possible as this will be dependent on the fuel type and applications.1.1 This test method covers three procedures for the determination of the filter blocking tendency (FBT) and filterability of middle distillate fuel oils and liquid fuels such as biodiesel and biodiesel blends. The three procedures and associated filter types are applicable to fuels within the viscosity range of 1.3 mm2 to 6.0 mm2/s at 40 °C.NOTE 1: ASTM specification fuels falling within the scope of this test method are: Specification D396 Grades No 1 and 2; Specification D975 Grades 1-D, low sulfur 1-D and 2-D; Specification D2880 Grades 1-GT and 2-GT; Specification D6751.1.2 This test method is not applicable to fuels that contain free (undissolved) water (see 7.3).1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 This test method assists in evaluating the effect of layout, typeface, type size, color, and background on the legibility of printed matter.5.2 Previous research3 has shown that results are more significantly impacted by subject age than any other effect. Older subjects tend to require more light when using this instrument. Because subjects age at different rates as a result of lifestyle and genetics, variability of data tends to increase with increasing age. This test method was developed using subjects of ages 19 to 28 years. It is advised that subjects age 19 to 28 be used in cases where variability needs to be kept to a minimum.5.3 Testers can compare legibility between various groups of subjects (by age, light intensity, distance, vision characteristics of the subjects) and one against other label configurations within groups of subjects1.1 This test method provides an objective means to comparatively measure the ease of reading printed matter for use in package labeling.1.2 This test method is not intended to quantify the legibility of a printed item against a standard but to compare its legibility against other items.1.3 This test method uses human subjects to view printed matter mounted in a specialized instrument.1.4 The user of this test method must be aware that results may differ from one age group of subjects to another.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 / 折扣价： 502 元 加购物车

5.1 Stray radiant power can be a significant source of error in spectrophotometric measurements. SRP usually increases with the passage of time; therefore, testing should be performed periodically. Moreover, the SRPR test is an excellent indicator of the overall condition of a spectrophotometer. A control-chart record of the results of routinely performed SRPR tests can be a useful indicator of need for corrective action or, at least, of the changing reliability of critical measurements.5.2 This test method provides a means of determining the stray radiant power ratio of a spectrophotometer at selected wavelengths in a spectral range, as determined by the SRP filter used, thereby revealing those wavelength regions where significant photometric errors might occur. It does not provide a means of calculating corrections to indicated absorbance (or transmittance) values. The test method must be used with care and understanding, as erroneous results can occur, especially with respect to some modern grating instruments that incorporate moderately narrow bandpass SRP-blocking filters. This test method does not provide a basis for comparing the performance of different spectrophotometers.NOTE 8: Kaye (3) discusses correction methods of measured transmittances (absorbances) that sometimes can be used if sufficient information on the properties and performance of the instrument can be acquired. See also A1.2.5.5.3 This test method describes the performance of a spectrophotometer in terms of the specific test parameters used. When an analytical sample is measured, absorption by the sample of radiation outside of the nominal bandpass at the analytical wavelength can cause a photometric error, underestimating the transmittance or overestimating the absorbance, and correspondingly underestimating the SRPR.5.4 The SRPR indicated by this test method using SRP filters is almost always an underestimation of the true value (see 1.3). A value cited in a manufacturer’s literature represents the performance of a new instrument, tested exactly in accordance with the manufacturer’s specification. The implication is that the manufacturer’s stated SRPR can serve as a benchmark for future performance, provided that the user performs the manufacturer’s specified test. It is recommended that users test new instruments promptly, thereby establishing a comparative benchmark in terms of their own testing facilities. The solution filter ratio method (4.3) is a convenient method for control-charting SRPR. Mielenz, et al., (4) show that its results tend to correlate well with those of the specified wavelength method, but for critical comparison with the manufacturer’s specification, the method used by the manufacturer must be used. Because some instruments reduce SRP by incorporating moderately narrow bandpass SRP-blocking filters that are changed as the wavelength range is scanned, it is possible for SRPR determinations to be highly inaccurate if the cutoff wavelength of the SRP filter falls too close to the absorption edge of an instrument’s SRP-reducing filter (3).1.1 Stray radiant power (SRP) can be a significant source of error in spectrophotometric measurements, and the danger that such error exists is enhanced because its presence often is not suspected (1-4).2 This test method affords an estimate of the relative radiant power, that is, the Stray Radiant Power Ratio (SRPR), at wavelengths remote from those of the nominal bandpass transmitted through the monochromator of an absorption spectrophotometer. Test-filter materials are described that discriminate between the desired wavelengths and those that contribute most to SRP for conventional commercial spectrophotometers used in the ultraviolet, the visible, the near infrared, and the mid-infrared ranges. These procedures apply to instruments of conventional design, with usual sources, detectors, including array detectors, and optical arrangements. The vacuum ultraviolet and the far infrared present special problems that are not discussed herein.NOTE 1: Research (3) has shown that particular care must be exercised in testing grating spectrophotometers that use moderately narrow bandpass SRP-blocking filters. Accurate calibration of the wavelength scale is critical when testing such instruments. Refer to Practice E275.1.2 These procedures are neither all-inclusive nor infallible. Because of the nature of readily available filter materials, with a few exceptions, the procedures are insensitive to SRP of very short wavelengths in the ultraviolet, or of lower frequencies in the infrared. Sharp cutoff longpass filters are available for testing for shorter wavelength SRP in the visible and the near infrared, and sharp cutoff shortpass filters are available for testing at longer visible wavelengths. The procedures are not necessarily valid for “spike” SRP nor for “nearby SRP.” (See Annexes for general discussion and definitions of these terms.) However, they are adequate in most cases and for typical applications. They do cover instruments using prisms or gratings in either single or double monochromators, and with single and double beam instruments.NOTE 2: Instruments with array detectors are inherently prone to having higher levels of SRP. See Annexes for the use of filters to reduce SRP.1.3 The proportion of SRP (that is, SRPR) encountered with a well-designed monochromator, used in a favorable spectral region, typically is 0.1 % transmittance or better, and with a double monochromator it can be less than 1×10-6, even with a broadband continuum source. Under these conditions, it may be difficult to do more than determine that it falls below a certain level. Because SRP test filters always absorb some of the SRP, and may absorb an appreciable amount if the specified measurement wavelength is not very close to the cutoff wavelength of the SRP filter, this test method underestimates the true SRPR. However, actual measurement sometimes requires special techniques and instrument operating conditions that are not typical of those occurring during use. When absorption measurements with continuum sources are being made, it can be that, owing to the effect of slit width on SRP in a double monochromator, these test procedures may offset in some degree the effect of absorption by the SRP filter; that is, because larger slit widths than normal might be used to admit enough energy to the monochromator to permit evaluation of the SRP, the stray proportion indicated could be greater than would normally be encountered in use (but the net effect is still more likely to be an underestimation of the true SRPR). Whether the indicated SRPR equals or differs from the normal-use value depends on how much the SRP is increased with the wider slits and on how much of the SRP is absorbed by the SRP filter. What must be accepted is that the numerical value obtained for the SRPR is a characteristic of the particular test conditions as well as of the performance of the instrument in normal use. It is an indication of whether high absorbance measurements of a sample are more or less likely to be biased by SRP in the neighborhood of the analytical wavelength where the sample test determination is made.1.4 The principal reason for a test procedure that is not exactly representative of normal operation is that the effects of SRP are “magnified” in sample measurements at high absorbance. It might be necessary to increase sensitivity in some way during the test in order to evaluate the SRP adequately. This can be accomplished by increasing slit width and so obtaining sufficient energy to allow meaningful measurement of the SRP after the monochromatic energy has been removed by the SRP filter. However, some instruments automatically increase sensitivity by increasing dynode voltages of the photomultiplier detector. This is particularly true of high-end double monochromator instruments in their ultraviolet and visible ranges. A further reason for increasing energy or sensitivity can be that many instruments have only absorbance scales, which obviously do not extend to zero transmittance. Even a SRP-proportion as large as 1 % may fall outside the measurement range.NOTE 3: Instruments that have built-in optical attenuators to balance sample absorption may make relatively inaccurate measurements below 10 % transmittance, because of poor attenuator linearity. The spectrophotometer manufacturer should be consulted on how to calibrate transmittance of the attenuator at such lower level of transmittance.1.5 High accuracy in SRP measurement is not always required; a measurement reliable within 10 or 20 % may be sufficient. However, regulatory requirements, or the needs of a particular analysis, may require much higher accuracy. Painstaking measurements are always desirable.1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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