1、 NJBST Co.,Ltd. QCD-016 Rev.:0 Page:1 of 3Title: DENSITOMETER CALIBRATION PROCEDUREDENSITOMETER CALIBRATION PROCEDURE黑 度 计 校 验 工 艺 规 程CONTROLLED 在控本UNCONTROLLED 非在控本COPY NO 副本编号：PREPARED BY 编制： DATE 日期：REVIEWED BY 审核： DATE 日期： APPROVED BY 批准： DATE 日期：NJBST Co.,Ltd. QCD-016 Rev.:0 Page:2 of 3Title: D
2、ENSITOMETER CALIBRATION PROCEDURE1. Scope This procedure covers the calibration of transmission densitometers used to perform radiographic film density measurements and provides a means of evaluating the reliability of transmission densitometers used for the measurement of radiographic film density.
3、 This procedure is prepared reference to SE-1079 “STANDARD PRACTICE FOR CALIBRATION OFTRANSMISSION DESITOMETERS“ of ASME Sect.2. Apparatus 2.1 Apparatus should consist of the following: 2.1.1 The X-ray film step tablet standard of the National Center of Measuring having at least 5 steps with neutral
4、 densities from at least 1.0 through 4.0. The calibration of the step wedge film shall have been verified within the last 12 month by comparision with a National Center of Measuring serialized step tablet.2.1.2 Transmission Densitometers with digital readout displays specifically manufactured for th
5、e purpose of measuring the range of film densities, described in 2.1.1 shall be used.2.1.3 Manufacturers Operating Instruction for Appropriate Transmission Densitometer.3. Calibration3.1 Full-scale linearity calibration of densitometer shall be performed at least every 90 days during use.3.1.1 Allow
6、 a minimum of 30min “warm-up“ time. After this warm-up period, adjust the “0“ reading of the densitometer.3.1.2 Select and position for reading the neutral density closest to 1.0，2.0，3.0，4.0 on the calibrated step tablet. Read and record the density for each step. 3.1.3 Compare the densities recorde
7、d with the actual density values listed on the calibrated or the density value listed on the calibration certificate. If the densitometer has been calibrated properly, the densities at 1.0，2.0，3.0，4.0 should not vary more than 0.05 density units. If any of the recorded density vary more than 0. 05 d
8、ensity units from the density values on the calibrated step tablet, the linearity of the densitometer is out of tolerance and shall be corrected. 4. Records and Associated Documentation4.1 Note and record the calibration reading in an appropriate 1.范围本规程用于对射线照相底片的黑度测量的黑度计的校验,使黑度计能够对射线底片黑度作出可靠的评定，本规程
9、按照 ASME 第卷 SE-1079“黑度计校验的实施标准”制定。2. 仪器2.1 仪器组成如下:2.1.1 中国国家计量中心 X 射线阶梯片(标准参考材料 1001)或其它阶梯黑度片，在 1.04.0 范围内至少应有 5 个阶梯黑度。阶梯片的校验应至少在最近 12 个月内与国家计量中心的 X 射线阶梯母片核对。2.1.2 黑度计应使用测量 2.1.1 所述底片黑度范围的数显型透射式黑度计。2.1.3 制造厂提供的黑度计操作说明书。3. 校验3.1 黑度计使用期间应至少 90 天作一次满刻度的线性校验。3.1.1 校验开始前或测试底片前，预热30min (或按制造商推荐)预热后将黑度计读数调到
10、零。3.1.2 在校正阶梯黑度表上,选择最接近于 1.0，2.0，3.0，4.0 黑度的测点进行测试。读出并记录各阶梯上测出的黑度值。3.1.3 将记录的黑度，与校正阶梯黑度表上 1.0，2.0，3.0，4.0 的实际黑度比较。若黑度计已作适当校准，则1.0，2.0，3.0，4.0 各阶梯上的黑度不得大于0.05。若记录的任何黑度值与校正阶梯黑度表上的黑度值相比，大于0.05，则黑度计线性超差，应予修正。4. 记录和有关文件4.1 在相应的校验登记薄上记录校正读数。在黑度计上加校验标签,校验标签上应表明校正的日期及进行校验的人员代号。5. 定期校验5.1 应在每班工作前，8 小时连续操作后，或
11、改变光孔等任一种情况最先出现时进行校验。5.1.1 如果校验的读数在校验日记中标定值的0.05 以内,该仪器可以使用NJBST Co.,Ltd. QCD-016 Rev.:0 Page:3 of 3Title: DENSITOMETER CALIBRATION PROCEDUREcalibration log. A calibration label that indicates the date the calibration was performed, and the identification of the individual performing the calibration,
12、 shall be applied to the densitometer to verify the calibration reference check recorded in the calibration log.5. Periodic Verification5.1 Periodic calibration verification check shall be performed at the beginning of each shift, after 8h of continuous operation, after change of operators, or chang
13、e of apertures, whichever occurs first.5.1.1 If the verification reading is within0. 05 of the values marked in the calibration log referenced in 4.1, the equipment is ready for use. If not, recalibration is required and shall be accomplished as detailed in 3.1.5.1.2 If the calibration verification check shows a variation grester than0.05, then all radiographs examined since the last acceptable daily density check shall be subject to a reverification for density after the densitometer has been recalibrated.否则, 应按 3.1 要求重新校验过后再确认。5.1.2 若校验得出的值超过标定值0.05,则自上次有效校验期后的所有底片都得在黑度计重新校验合格后再作评定。
