Overview

Calibrating the HFRR can be performed in approximately 5-10 minutes. Calibration is primarily required to check if the instrument is working correctly if for example a test fails, although we recommend calibration every three months as good practice. The alarm RTD does not have to be recalibrated periodically after once set.

The HFRR calibration kit comprises of a Calibration device including stroke gauge (Part code:HFRCAL) and temperature calibration plugs (Part code:HFRCAL2).

HFRR Calibration device

The HFRR is supplied with a combined calibration device for stroke length, force transducer and contact resistance calibration.

Part code: HFRCAL.

Temperature calibration plugs

The temperature calibrator plugs simulate the temperature between two set points. The lower calibration set point is 0°C and higher set point is 62°C.

Part code: HFRCAL2

After each calibration, the new calibration constants are saved in the instrument's flash memory. These can be accessed either directly using the keypad, or, if the system is attached to the PC by downloading the calibration information. Note that the calibration values cannot be changed manually.

The list below shows what can be calibrated/checked on the HFRR rig.

• Stroke Length - Calibrates mechanical unit LVDT that will control the stroke length of the pushrod.
• Force Transducer - Calibrates the mechanical unit force transducer that will measure the friction coefficient.
• Film Sensor - Calibrates the ECR (electrical contact resistance) of the HFRR. This is measured between the mechanical unit pushrod and heater block.
• Main Temperature Probe (RTD) - Two temperature calibration plugs (0°C and 62°C) are used to calibrate the HFRR so the temperature to the lower specimen holder can be read accurately.
• Alarm Temperature Probe (RTD) - Sets the maximum heat allowed to the heater block and will shut down the heaters if exceeded. This is normally set to 10°C above the test temperature as a safety feature of the rig..
• Stroke Length Check - Checks that the HFRR is measuring the stroke length correctly.

Recalibrating Services

It is recommended to recalibrate the calibration device every two years. A certificate will be supplied confirming that the device has the correct force value and is in good working order.

The temperature calibration plugs cannot be recalibrated although they can be checked so they comply with the test standards.

For recalibration please contact your local distributor or PCS Instruments.