The core equipment for testing the time constant of hot runner sensors includes a thermostatic bath, a thermal oil bath, a high-speed data acquisition system, a temperature recorder, and a self-heating test device. These devices accurately measure the sensor's response speed by simulating temperature steps or cooling processes.
1. Thermostatic Bath and Thermal Oil Bath (Provides a stable temperature field)
Function: Used to create controllable low and high temperature environments to achieve temperature step testing;
Recommended Models: Precision water bath thermostatic bath (e.g., Julabo F34 HC) High-temperature thermal oil bath (e.g., Huber Unistat 915w)
Applicable Scenarios: Rapidly transferring sensors from a low-temperature environment to a high-temperature oil bath and recording their temperature rise response process.
Advantages: Temperature control accuracy up to ±0.1℃, meeting the requirements of GB/T 30121-2013 standard.
2. High-Speed Data Acquisition System (Accurate Recording of Dynamic Response)
Function: Records sensor output voltage or resistance changes at millisecond-level sampling frequencies;
Core Components: Multi-channel data acquisition card (e.g., NI USB-6216)
Paired with SCQ-04 type intelligent data acquisition unit (supports dual input of thermocouple and heat flux sensor)
Software Support: LabVIEW or customized analysis program for automatic calculation of the 63.2% response time τ.
Engineering Applications: Captures the sensor's rapid response characteristics within 0.5 seconds in dynamic fluid testing.
3. Self-Heating Test Device (Suitable for NTC Sensors)
Components: Adjustable DC power supply (provides constant excitation current)
Digital multimeter or voltmeter (monitors voltage changes)
Static air test chamber (controls ambient wind speed and humidity)
Test Principle: Utilizes current to cause the NTC to self-heat, then disconnects power for cooling, recording the time required for the temperature to drop to 63.2% in the cooling curve.
Note: The time constant measured by this method is relatively large and should only be used as a preliminary evaluation reference.
4. Flow Medium Testing Platform (Simulating Real-World Operating Conditions)
Structure: A circulating pump drives the flow of heat transfer oil or air. The sensor to be tested is installed inside the pipeline. Temperature surge testing is achieved under controllable flow rates.
Parameter Control: Flow rate range 0.5~2 m/s, temperature difference can reach over 60℃.
Value: Closer to the actual operating environment of hot runners, enhancing the engineering guidance significance of the test results.
