RP

LS_CHT_BIA_L36_Maintenance in Thermal Analysis

Lesson 36: Maintenance in Thermal Analysis

Lesson Objectives

  • Cleaning of detector

  • Maintenance of DSC system

  • Standard calibration procedure for DSC system

Cleaning of Detector

  • Purpose: Remove substances formed during analysis.

  • Inspection: Check sample/reference pans, lids, and crucibles for contaminants before and after each use.

  • Cleaning function in TA-60W software:

    • Increases temperature to 600°C immediately and holds it constant for the set time.

Cleaning Procedure

  1. Ensure no sample runs remain on the detector.

  2. Click {Detector}-{Cleaning Run…}

  3. Enter {Hold Time(min)}, select gas type, and press {Start}.

    • Cleaning gas example: Air at 200-300 ml/min.

Maintenance

  • Hardware Maintenance:

    • Clean instrument’s exterior with a cloth soaked in ethanol.

  • Long Storage:

    • Disconnect gas pipelines and close respective ports.

    • Close furnace lid and cover; ensure no items on detector plate.

    • Store away from sunlight, dust, and vibration.

  • Vacuum System:

    • Ensure functioning properly; check for leaks and vacuum pump condition.

Performance Maintenance

  • Check performance by measuring melting temperature and heat of fusion of standard material (e.g., Indium).

  • Heat indium sample from ambient to 180°C at 10°C/min:

    • Accepted range: Tm = 156.5 ± 1.0°C, Heat of fusion = 27 ~ 30 J/g.

  • Perform calibration if results are outside the accepted range.

  • Recommended checks: once a month or preferably weekly.

Calibration Procedure

  1. Enter TA-60 collection program.

  2. Ensure DSC-60 is connected.

  3. Click DETECTOR menu and select TEMPERATURE CALIBRATION.

  4. Click CALCULATE.

  5. Set Expected & Measured values for:

    • Indium: 156.63°C

    • Zinc: 419.58°C

  6. Click OK.

Additional Calibration Steps

  • Set Coefficient A & B to 0.00000.

  • Click DOWNLOAD, then YES, and EXIT.

  • Click DETECTOR menu and select HEAT CALIBRATION.

  • Set Expected & Measured values to:

    • 28.45 J/g

  • Click OK, DOWNLOAD, then YES, then EXIT.

Sample Run Preparation

  1. Place Indium sample in DSC-60, fill in:

    • Sample Name: Indium

    • Sample Weight: 5.5 mg

    • Pan: Aluminium

    • Atmosphere: Nitrogen

    • Rate flow: 50 ml/min

  2. Program for Indium:

    • Hold Temp: 200.0°C, Rate: 10.00°C/min.

  3. Analyze using DSC Peak analysis after the run.

  4. Repeat for Zinc sample:

    • Sample Weight: 3.56 mg

    • Hold Temp: 500.0°C, Rate: 10.00°C/min.

Inspect and Clean Gas Flow Path

  • Check gas flow path and connections; clean/replace as necessary.

  • Inspect electrical connections for damage or loose fittings.

  • Check seals and gaskets for wear; replace as needed.

  • Replace gas filters as per manufacturer recommendations.

Troubleshooting Symptoms

  • Abnormal Temperature Indication:

    • Replace defective cold junction element.

    • Ensure correct connections for detector thermocouples.

  • Temperature Doesn’t Rise:

    • Check for blown/missing fuse.

    • Ensure proper connection at heater terminal.

  • Temperature Deviates:

    • Change control constants for stability.

    • Address issues with wiring and power supply.

References