Automated Thermal Characterization Tool for Heated Hoses

Context

Heated hoses and heated analysis lines are used to maintain a controlled temperature along flexible piping. Applications range from industrial measurement systems to processes in which temperature-sensitive materials such as chocolate or honey need to remain flowable during transport.

For custom-designed heating solutions, the temperature distribution along the hose had to be characterized to verify that it heated uniformly. The measurements were used both for R&D verification and quality assurance.

Previously, this was performed manually. Temperature values were measured at selected positions along the hose and entered into Excel for subsequent evaluation. Because a complete measurement typically took 30 minutes to one hour, the process required considerable operator attention and limited the practical number of measurement points.

The objective was to automate the data-acquisition process while retaining the established downstream evaluation workflow.

My Role

I developed the complete C# / WPF application and automated test workflow from scratch.

My responsibility covered the user interface, test sequencing, motion-control integration, communication with the measurement instrument and heating controller, data acquisition, test configuration, timing calculations, manual control, fault and abort handling, CSV generation and storage.

The mechanical test rig itself already existed in an earlier form. It had originally been developed by a mechanical-engineering intern using a stepper-driven mechanism to extend and retract a temperature sensor along the heating hose.

Before the software development, the measurement concept was mechanically improved by a colleague: the original PT100 arrangement was replaced with a more rigid Type K thermocouple, and a rolling drum was added to manage the sensor cable during automatic retraction.

My work focused on turning this mechanical measurement concept into a controlled, automated test system.

Test System

The test setup combines several independent components under control of the PC application:

• Motorized positioning mechanism for moving the thermocouple along the hose
• Type K thermocouple for local temperature measurement
• Thermocouple measurement instrument connected to the PC via USB / virtual COM port
• Heating controller connected to the application through a COM interface
• C# / WPF application coordinating movement, timing, measurement and data recording

The application sends commands to the stepper-motor system to position the thermocouple and reads the measured temperature automatically from the thermocouple instrument using its data-transfer protocol.

Communication with the heating controller allows the software to monitor the heating process and begin the spatial measurement once the specified temperature condition has been reached.

Configurable Measurement Sequence

Before starting a test, the engineer configures the measurement according to the hose being evaluated.

Parameters include:

• hose length
• number and spacing of measurement points
• equilibrium time after each movement
• forward-only or forward-and-return measurement
• distribution of measurement positions

Measurement points do not have to be evenly distributed. For long hoses, the engineer can use larger spacing through the middle of the hose while measuring more closely near the beginning and end, where the temperature profile is more relevant.

From the configured sequence, the software calculates an estimated test duration before the measurement starts. This was particularly useful because a complete test commonly runs for 30 to 60 minutes and no longer requires the operator to remain at the test station throughout the measurement.

Automated Measurement

Once the heating hose is mounted and the test parameters are entered, the operator starts the measurement.

The application waits for the required heating condition and then performs the configured sequence automatically:

Move thermocouple → stop at measurement position → wait for equilibrium → acquire temperature → record value → move to next position

This continues until all configured positions have been measured.

The thermocouple position is derived from the calibrated relationship between stepper-motor movement and linear sensor travel. Correct mechanical calibration and zeroing were therefore important parts of commissioning the automated system, particularly to keep the calculated position aligned with the physical sensor position over the hose length.

When the sequence is complete, the application notifies the operator.

A separate manual mode is also available. The thermocouple can be moved using the keyboard and individual temperature values can be recorded manually at the press of a button when an automated sequence is not appropriate.

Data Acquisition & Existing Analysis Workflow

The purpose of the new software was to automate measurement, not to unnecessarily replace an established evaluation process.

After completing a test, the application exports the acquired position and temperature data as a CSV file structured specifically for compatibility with the existing Excel macros.

The established Excel workflow could therefore continue to perform the subsequent processing and evaluation without modification.

This kept the project focused on the part of the process that consumed the most engineering and operator time: collecting a consistent spatial temperature profile along the heating hose.

Fault & Emergency Stop Handling

A running test stops if communication with the required equipment is lost.

The operator can also stop the experiment immediately through either:

• a software emergency stop using the space bar
• an external emergency-stop button integrated into the test setup

The application was designed so that an interrupted measurement does not continue after loss of communication.

Result

The automated system completely replaced the previous manual data-collection method for these measurements.

Instead of manually moving the sensor, waiting, reading each temperature and entering the result into Excel, an engineer can configure the hose and measurement sequence, start the experiment, see the estimated completion time and continue with other work while the system collects the temperature profile automatically.

Automation also made it practical to use more measurement points without increasing operator workload, increasing the amount of spatial data available for evaluating custom heating solutions.

The system is used by both production and R&D for custom, non-series heating solutions. It has remained in operation since its introduction approximately four years ago and is still in use today. Based on practical experience, it is estimated to have been used for at least 300 measurements during that period.

For me, the project is particularly representative of multidisciplinary engineering: software development had to work together with an existing mechanical system, motion control, temperature measurement, heating-controller communication and established workflows used across different departments.

Technologies

C# WPF Test Automation Serial Communication USB COM Ports Stepper Motor Control Type K Thermocouple Temperature Measurement Data Acquisition CSV Excel Integration