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

• Principles of Instrumental Analysis (5th Edition) Skoog, Holmer, Nieman.

• Differential Scanning Calorimetry Resources