工艺范围与校准范围及公差(允差)之间的关系

When deciding on calibration ranges and limits, the instrument ranges, the manufacturer’s accuracy, and the process requirements should be taken into account. Process ranges, tolerances, alert, and action limits are interrelated.

在确定校准范围和限值时，需综合考虑仪器的量程、制造商的精度以及工艺要求。工艺范围、公差、警戒限和行动限之间存在着密切的相互关联。

The full range of an instrument may prove most appropriate for the calibration range. Conversely, for instruments that have a full calibrating range much greater than the actual operating values, it may be appropriate to reduce the maximum and minimum calibration range closer to that of the standard operating values.

对于某些仪器而言，其全量程或许是最为理想的校准范围。然而，对于那些校准范围远超实际操作值的仪器，将最大和最小校准范围缩小至更贴近标准操作值的区间，可能更为适宜。

Suitable test points across the process range should be defined to ensure that instrument accuracy and precision is clearly demonstrated. For a critical loop, these should include rising and falling values, and wherever possible, values close to operating setpoints and any critical decision limits.

应在整个过程中合理定义测试点，以确保清晰展示仪表的准确性和精密度。对于关键回路，测试点应涵盖上升和下降值，并在可能的情况下， 涵盖接近操作设定值及所有关键决策限值的数值。

Where performance and operating history of instrumentation is not available, it is recommended that full scale calibration ranges should be adopted for the initial calibrations performed. As suitable evidence and trend data accumulates, a review may be performed, and where appropriate, adjustments to the calibration limits can be justified.

在无法获取仪表性能及运行历史数据的情况下，建议在初始校准阶段采用全量程校准范围。随着相关证据和趋势数据的逐步积累，可以进行定期审查，并在适宜的情况下，对校准限值进行相应调整。

See Appendix 1 for an overview of the relationship between Process Limits and Calibration Ranges and Tolerances.

有关 工艺限值与校准范围及公差之间关系 的概述，请见附录 1 。

Appendix 1 – Worked Example Showing Tolerance 公差设定示例

Setting and using process alarm, calibration adjustment, and tolerance.

设定和使用 工艺 报警、校准调整以及公差。

Figure 10.1 provides an example for a fictional case where the product being processed needs to be controlled to 5 ℃ ±3 ℃ . Processing outside this temperature range will result in out of spec material. It is known that the control system can consistently achieve ±2 ℃ , this allows ±1 ℃ for the instrument. The instrument itself is capable of achieving ±0.4 ℃ . The settings are therefore:

图 10.1 提供了一个虚构案例的示例：被处理的 产品需要控制在 5 ℃ ±3 ℃ 的温度范围内 。超出此温度范围进行加工将导致物料 不符合 标准 。已知 控制系统能稳定 控制在 ±2 ℃ 内 ，这为 仪表留出了 ±1 ℃ 的余量 。而 仪表本身能够达到 ±0.4 ℃ 。因此，设定如下：

o Process Alarm Limit ±2 ℃ 工艺报警限： ±2 ℃

o Tolerance: ±1 ℃ 公差： ±1 ℃

o Calibration Adjustment Limit: ±0.4 ℃ 校准调整限： ±0.4 ℃

Figure 10.1: Example – Control to 5 ℃ ±3 ℃ 示例 – 控制目标为 5 ℃ ±3° ℃

C and E: Process Control

The shown/recorded reading has exceeded the Process Alarm Limit ; adding in the allowable error for the temperature instrument (1 ℃ ), it can be seen that the absolute allowable value may have been exceeded and an alarm must be raised to test the quality of the product made at that time.

显示或记录的读数已超出 工艺报警 限值；鉴于温度仪表的 允许误差为 1 ℃ ，可以 判断绝对允许值 可能已被 超出 ，因此必须立即触发报警，并对该时段内生产的产品质量进行检验。

B, D, F, and G: Scheduled Calibrations

Calibrations are carried out at regular, timed intervals, indicated at points B, D, F, and G and marked:

校准在 固定 的时间间隔内进行，分别在 B 、 D 、 F 和 G 点进行，标记为：

Thearrows: indicate the ‘as found reading’ error.

箭头： 指示 校准前读数 的误差。

Thedotted line then indicates what the actual value may have been assuming the

founderror to have been present at all times since the previous calibration.

虚线： 虚线则表明，假定自上次校准以来所发现的误差一直存在，实际值可能达到的范围。

Calibration checks at B and G show that the tolerance has been exceeded and an exception report should be raised and an investigation carried out on the product made and/or process conditions since the previous calibration.

校准检查 B 和 G 的结果显示，公差已超出，应立即启动偏差程序，并对自上次校准以来生产的产品及 / 或工艺条件进行调查。

The calibration check at B will trigger an investigation of the process conditions between B and the previous calibration check. In this case, a potential problem at A will be highlighted, indicating that the actual temperature may have exceeded the absolute alarm condition of 8 ℃ . Product made at this time will need to be tested for quality.

校准检查 B 将启动对 B 点与上次校准检查点之间工艺条件的调查。 在此案例中， A 点处的潜在问题将得以显现，表明实际温度可能已超出 8 ℃的绝对报警值。 该时段内生产的产品需进行质量检验。

The calibration check at G will trigger an investigation of the process conditions between G and the previous calibration check at F . In this case, it can be seen that there is no potential for the product processing temperature to have exceeded the absolute alarm condition, and all that is needed is an investigation of the instrument before adjusting it to within its calibration adjustment limits or replacing/repairing it.

在 G 点进行的校准检查将引发对 G 点与前一次在 F 点进行的校准检查之间工艺条件的调查。在这种情况下， 可以看出产品加工温度没有超出绝对报警条件的可能，只需要对仪器进行调查，然后将其调整到校准调整范围内，或者进行更换 / 维修即可。

The calibration check at F shows that the tolerance has not been exceeded, but that the calibration adjustment limits have been exceeded and the instrument can be simply adjusted to within its adjustment limits.

校准检查 F 的结果显示， 公差未被超出 ，但 校准调整限已被超出 。此时， 仅需将仪器简单调整至其调整限内 。

The calibration check at D shows that the instrument has not exceeded its adjustment limits and no further action is required.

校准检查 D 的结果表明，仪器未超出其调整限值，因此无需采取进一步措施。