Yes, the **reference standard** placed in the dry block calibrator must have a valid calibration certificate to ensure the accuracy and traceability of its measurement results. Here are the specific reasons and relevant regulatory support:

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### 1. **Calibration specifications and regulatory requirements**

- According to **JJF 1257-2010 "Calibration Method for Dry Block Temperature Calibrators", the reference standard thermometer used in calibrating the dry block must be **traceable to a national or international temperature benchmark**, and its calibration certificate must contain complete measurement data and uncertainty assessment.

- The **GMP specification** of the pharmaceutical industry clearly requires that standard instruments used for calibration must provide a traceable calibration certificate with an expiration date and a metrological qualification certificate number.

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### 2. **Accuracy assurance of the calibration process**

- The **core steps of dry block calibration** include verifying the accuracy of the reference standard. For example, during the dry block calibration process, the reference standard needs to be compared with the instrument being calibrated. If the reference standard is not calibrated, it may cause systematic errors.

- The calibration certificate ensures that the key parameters of the reference standard, such as **temperature deviation, stability, uniformity**, meet the requirements (such as temperature fluctuation ≤ 0.04℃), thereby ensuring the reliability of the overall calibration results of the dry block furnace.

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### 3. **International standards and industry practices**

- **ISO/IEC 17025** stipulates that the reference standards used in the laboratory must be calibrated regularly and have traceability certificates to meet international mutual recognition requirements.

- For example, the calibration scheme of **PANRAN dry block furnace** explicitly requires the use of reference probes with **NIST or EA traceability certificates** to ensure the strict requirements of the pharmaceutical industry for cleanliness and compliance.

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### 4. **Specific content requirements of the calibration certificate**

- The calibration certificate should contain the following information:

1. **Unique identification** of the reference standard (such as model, serial number);

2. **Calibration date and validity period**;

3. Measurement results and **uncertainty assessment**;

4. Statement of traceability to international or national standards

- For special applications of dry block furnaces (such as short probe calibration), the certificate must also state the performance of the reference standard under **specific load conditions**.

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### 5. **Risk avoidance in practical applications**

- If the reference standard is not calibrated, it may lead to:

- Temperature deviation in the production process (such as product quality risk in the pharmaceutical industry);

- Calibration report rejected by auditing agencies (such as FDA, EU);

- Legal disputes caused by non-traceability of data.

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### Conclusion

To ensure the compliance and accuracy of dry block calibration, the reference standard must have a valid and traceable calibration certificate. It is recommended to follow the following steps:

1. **Regular calibration**: Update the calibration certificate of the reference standard according to industry standards (usually once a year);

2. **Select an accredited body**: Prefer calibration by a laboratory accredited by **ILAC-MRA** or **CNAS**;

3. **Record management**: Clearly cite the certificate information of the reference standard in the calibration report for traceability.