1、Designation: E1079 16Standard Practice forCalibration of Transmission Densitometers1This standard is issued under the fixed designation E1079; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in p
2、arentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice2covers the calibration of transmissiondensitometers used to perform radiographic film density mea-surements (see Note 1).1.2 This st
3、andard 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.NOTE 1For further informat
4、ion on the design and use ofdensitometers, the following literature is suggested as additional back-ground information: ISO 51:2009, ISO 52:2009, ISO 53:2009, andISO 14807:2001.2. Referenced Documents2.1 ASTM Standards:3E1316 Terminology for Nondestructive Examinations2.2 ISO Standards:4ISO 53:2009
5、Photography and Graphic Technology - Den-sity Measurements - Part 3: Spectral ConditionsISO 14807:2001 Photography - Transmission and ReflectionDensitometers - Method for Determining Performance3. Terminology3.1 DefinitionsFor definitions of terms used in thispractice, see Terminology E1316.4. Signi
6、ficance and Use4.1 This practice provides a means for calibrating transmis-sion densitometers used for the measurement of radiographicfilm density. A transmission densitometer calibrated in accor-dance with this practice provides the assurance that accuratedensity values of radiographs are obtained.
7、5. Apparatus5.1 Apparatus should consist of the following:5.1.1 A calibrated step tablet covering the density rangeused in production radiographs shall be used. The step tabletmay be a NIST X-ray Step Tablet (X-Ray Film Step TabletTransmission Density Standard 38100C)5, or alternately a steptablet f
8、rom another supplier that is traceable to the NIST steptablet in the range provided by NIST certification. The steptablet shall have at least five step densities, which cover thedensity range that is used for production radiographs. Acalibration certificate shall be provided with the step tabletindi
9、cating the tablet ID and recorded values for each stepdensity. For suppliers of step tablets other than NIST, thecertificate shall indicate conformance of traceability to NIST,applicable ISO or ANSI standards (for example, ISO 53)used, verification of measurement on a NIST step tablet, the IDnumber
10、of the step tablet, and calibration date of the step tablet.Precautions should be taken in the storage, handling, and use ofthe step tablet. In the event it becomes scratched, blemished, orexhibits other signs of deleterious wear, it should be replacedimmediately. The NIST (or alternate, if used) st
11、ep tablet shallbe replaced four years from the date of first use.65.1.2 Transmission Densitometers, with either direct-scalereadout or digital readout displays specifically manufacturedfor the purpose of measuring the range of film densitiesdescribed in 5.1.1 may be used.5.1.3 Manufacturers Operatin
12、g Instructions for Appropri-ate Transmission Densitometer.6. Calibration6.1 Full-scale linearity calibration should be performed atleast every 90 days during use as follows:6.1.1 Use the manufacturers recommended warm-up timeto stabilize circuitry before starting the calibration procedure orthe peri
13、odic verification checks described in Section 7. Adjustthe “0” reading of the densitometer after the warm-up period.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.01 onRadiology (X and Gamma) Method.Curre
14、nt edition approved June 1, 2016. Published June 2016. Originallyapproved in 1985. Last previous edition approved in 2010 as E1079 - 10. DOI:10.1520/E1079-16.2For ASME Boiler and Pressure Vessel Code applications see related PracticeSE-1079 in Section II of that Code.3For referenced ASTM standards,
15、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 ASTM website.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New Y
16、ork, NY 10036.5Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.6Expiration interval of the NIST or alternate step tablet may be different than therequirements of this practice. Unless otherwise specified,
17、 requirements of thispractice shall apply.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.1.2 Select and measure three steps on the calibrated steptablet densities below, above, and near the midpoint of therange that is used for pro
18、duction radiographs.6.1.3 Compare the measured densities with the actual den-sity values on the calibrated step tablet or the density valueslisted on the calibration certificate. Calibrate the densitometer,in accordance with manufacturer recommendations, in order toachieve measured densities which a
19、re as close as possible tothe actual density values on the step tablet. If the densitometerhas been calibrated properly, the measured densities at thethree steps should not vary more than 60.05 density units fromthe actual step tablet density values. If any of the measureddensity values vary more th
20、an 60.05 density units from thedensity values on the step tablet, the linearity of the densitom-eter is out of tolerance and should be taken out of service untilcorrected and recalibrated.6.2 Any densitometer that is dropped, repaired, or has hadcritical parts replaced should be recalibrated prior t
21、o use.7. Periodic Verification7.1 Periodic calibration verification checks using the proce-dure described in Section 6 should be performed at thebeginning of each shift, after 8 h of continuous operation, orchange of apertures, whichever occurs first.7.1.1 If the verification reading is within 60.05
22、 of thedensity values listed on the calibration step tablet or calibrationcertificate, the densitometer is ready for continued use. If thedensity values are not within the tolerance, recalibration isrequired and it shall be performed in accordance with Section6.7.1.2 If the verification check shows
23、a variation greater than60.05, then all radiographs examined since the last acceptabledensity check shall be subject to a re-verification for densityafter the densitometer has been recalibrated.7.2 Consult the Manufacturers Technical Manual fortroubleshooting information.8. Records and Associated Do
24、cumentation8.1 Note the densitometer calibration and periodic verifica-tion acceptance condition in an appropriate log. This log shallalso indicate the date the calibration/verification was per-formed and the identification of the individual who performedthe calibration/verification and shall be tra
25、ceable to the appli-cable densitometer. The retention period for calibration/verification documentation should be agreed upon by thepurchaser and supplier.8.2 An alternative calibration/verification documentationsystem may be used provided the calibration/verification trace-ability requirements iden
26、tified in 8.1 can be satisfied anddocumented properly. A pressure sensitive label or tag thatindicates the date the calibration/verification was performed,and the identification of the individual performing thecalibration/verification, may be applied to the densitometer forverification of the calibr
27、ation reference check recorded in thecalibration/verification log.8.3 Note and record the date of first use of the calibration/verification step tablet so that the requirements of 5.1.1 can besatisfied.9. Keywords9.1 calibration; densitometer; density; periodic verification;radiographic filmASTM Int
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29、y their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand sh
30、ould be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on St
31、andards, 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). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 162
