黑度计校验工艺规程

NJBST Co Ltd QCD 016Rev 0Page 1 of 3 Title DENSITOMETER CALIBRATION PROCEDURE DENSITOMETER CALIBRATION PROCEDURE 黑黑 度度 计计 校校 验验 工工 艺艺 规规 程程 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 016Rev 0Page 2 of 3 Title DENSITOMETER CALIBRATION PROCEDURE 1 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 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 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 the purpose of measuring the range of film densities described in 2 1 1 shall be used 2 1 3 Manufacturer s Operating Instruction for Appropriate Transmission Densitometer 3 Calibration 3 1 Full scale linearity calibration of densitometer shall be performed at least every 90 days during use 3 1 1 Allow 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 recorded 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 density 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 Documentation 4 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 0 4 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 016Rev 0Page 3 of 3 Title DENSITOMETER CALIBRATION PROCEDURE calibration log A calibration label that indicates the date the calibration was performed and the identification of the individual performing the calibration shall be applied to the densitometer to verify the calibration reference check recorded in the calibration log 5 Periodic Verification 5 1 Periodic calibration verification check shall be performed at the beginning of each shift after 8h of continuous operation after change of operators or change of apertures whichever occurs first 5 1 1 If the verification reading is within 0 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 than 0 05 then all radiographs examined since the las