To perform on-site temperature and pressure calibration in accordance with ISO 17025, you'll need to follow a set of defined steps to ensure that your process is accurate, traceable, and meets the required standards. Here's a guide to help you get started:

1. Understand ISO 17025 Requirements

ISO 17025 outlines the general requirements for the competence of testing and calibration laboratories. It ensures that your calibration procedures are accurate, reliable, and meet traceability requirements.

• Competence: The personnel conducting the calibration must have the appropriate qualifications and experience.

• Traceability: Calibration equipment must be traceable to national or international standards (e.g., NIST or UKAS).

• Environment: Ensure the on-site environment is controlled in terms of temperature, humidity, and other factors that might affect calibration.

2. Prepare Your Equipment

You’ll need specific calibration equipment for temperature and pressure calibration:

For Pressure Calibration:

• Precision Pressure Calibrator: For pressure, you need a high-accuracy calibrator that can cover the range of pressures you will be working with (e.g., up to 400 bar). The calibrator should be traceable to national or international standards.

• Reference Pressure Gauge: This will be used for comparing the readings of the pressure gauges you are calibrating. The reference gauge must have an accuracy greater than or equal to the pressure gauges you're calibrating.

• Calibration Pump (if required): If you're working with a pressure range that requires manual pumping (e.g., 0-400 bar), you'll need a high-quality pressure pump to generate known values.

For Temperature Calibration:

• Temperature Source (Dry Block, Liquid Bath, or Furnace): A portable dry block or liquid bath is ideal for on-site temperature calibration. These tools generate precise, stable temperatures at various points in the range.

• Reference Thermometer: A high-precision thermometer or temperature probe, which is traceable to national or international standards (e.g., NIST, PTB). It is used to compare the reading of the thermometer or temperature sensor under test.

• Thermocouple or RTD: Depending on the type of temperature sensors you are calibrating, you’ll need a reference standard that matches the sensors' type (thermocouple, RTD, etc.).

3. Follow ISO 17025 Calibration Procedures

Create detailed procedures for both temperature and pressure calibration based on ISO 17025 standards. Here’s what to include in the procedure:

General Steps for Both Temperature and Pressure Calibration:

1. Preparation:

• Ensure all equipment is properly calibrated and traceable.

• Check that your working environment is suitable for calibration (i.e., avoid extreme temperature, humidity, or vibrations).

• Verify that you have the required tools: reference gauges, temperature sources, multimeters, or handheld communicators.

2. Connect Equipment:

• For Pressure Calibration: Connect the pressure gauge under test to the precision pressure source and reference gauge.

• For Temperature Calibration: Place the temperature sensor (under test) in the temperature source (e.g., dry block or bath) and connect the reference thermometer to a suitable measurement device.

3. Apply Calibration Points:

• For Pressure Calibration: Apply different pressure values (e.g., 0%, 25%, 50%, 75%, and 100% of full scale) and compare the readings of the pressure gauge under test to the reference gauge.

• For Temperature Calibration: Apply different temperature set points (e.g., 0°C, 25°C, 50°C, 75°C, and 100°C) and compare the readings of the test sensor to the reference thermometer.

4. Check Linearity and Accuracy:

• Check that the gauge or sensor’s readings are within the specified tolerance for each applied calibration point. Adjust the equipment under calibration if necessary to match the reference value.

5. Adjust the Equipment (if necessary):

• Make any necessary adjustments to the equipment (e.g., zero or span adjustments for pressure gauges, calibration adjustments for temperature sensors).

6. Document Results:

• Record the calibration data for each point, including the pressure or temperature applied, the reading of the reference equipment, and the reading of the equipment being calibrated.

• Document any adjustments made and any issues encountered during calibration.

7. Re-verify After Adjustments:

• After making adjustments, verify the calibration by re-testing the equipment at various points and confirming that it’s within tolerance.

4. Ensure Compliance with ISO 17025:

• Documentation and Traceability:

• Calibration Certificates: You’ll need to generate calibration certificates for each piece of equipment, documenting the calibration results and ensuring traceability to national/international standards.

• Calibration Records: Maintain detailed records of each calibration, including the equipment used, the reference standards, calibration data, and any adjustments made.

• Environmental Conditions: Document the environmental conditions during calibration (e.g., temperature and humidity) since they can impact results.

• Personnel Qualifications:

• Ensure that personnel conducting the calibration are qualified and trained according to the requirements outlined in ISO 17025.

5. Periodic Verification and Maintenance:

• Routine Audits: Perform internal audits to verify that your calibration processes continue to meet ISO 17025 standards.

• Calibration Intervals: Establish and maintain appropriate calibration intervals for all instruments based on manufacturer recommendations, use case, and the importance of accuracy in your processes.

6. Calibration Equipment Traceability:

Ensure that all of your calibration equipment (pressure gauges, thermometers, pressure calibrators, etc.) is traceable back to a national or international standard (e.g., NIST, PTB). You may need to provide certificates of traceability to demonstrate compliance.

Key Tips for On-Site Calibration:

• Portable Calibration Systems: Use portable systems where possible to facilitate on-site calibration.

• Testing under Operational Conditions: Perform calibration under conditions as close to the equipment’s typical operating environment as possible, considering factors like pressure, temperature, and vibration.

• Environmental Control: For temperature calibrations, ensure that the ambient conditions (such as temperature and humidity) do not significantly impact the results.

Summary of Key Steps:

1. Review ISO 17025 requirements and understand the standards.

2. Gather and prepare the appropriate calibration equipment for temperature and pressure.

3. Perform the calibration at various points (0%, 25%, 50%, 75%, 100% of the range).

4. Verify accuracy, adjust if necessary, and document the results.

5. Ensure traceability and maintain proper records for audits and certification.

If you need more details about any of the steps or equipment, let me know!