Operation and Calibration of Vacuum Oven

  1.  Objective

To lay down a procedure for operation and Calibration of vacuum oven. It is used for determination for loss on drying.

  • Scope

This SOP is applicable for operation of vacuum oven (Make: LABCO) in Quality Control.  

  • Responsibility

QC Chemist / Officer : Follow the procedure and maintain record as applicable.   

  • Accountability

Head Quality Control  : System Compliance

  • Procedure:  
    • Operation:
      • Ensure that vacuum oven is clean.
      • Check the calibration due date.
      • Ensure that vacuum pump is attached properly.
      • Open the door, place the sample and close the door tightly.
      • Switch ON the mains.
      • Switch ON the oven by pressing the green main indicator switch downwards.
      • Set the temperature on the temperature gauge by pressing Ú or Ù and then press enter key.
      • On the vacuum pump, open the valve and let it attain the required vacuum in mm Hg.
      • After attaining the required vacuum close the valve and off the vacuum pump.
      • Start the heater by pressing red load indicator switch downwards.
      • Control the speed of heating by rotating the regulator knob at desired rate.
      • After completion of work press the red load indicator switch to upward to off the heater.
      • Then release the vacuum by opening the valve.
      • Finally press the green main indicator switch to upward to off the oven.
      • Open the door, remove the sample and close the door.
      • Enter the details in Instrument log.
      • In case any problem exists inform to Engineering Department.
      • Sample placed time in vacuum oven and withdrawn time from vacuum oven and actual temperature shall be recorded on test data sheet.
    • Calibration:
      • Operate the equipment.
      • Set the vacuum at pressure 760mm/30inch.
      • Set the temperature of oven at 60ºC.
      • Insert the calibrated thermometer (110 ºC) from the side hole.
      • Leave the instrument till the desired temperature is obtained.
      • Record the reading of thermometer on annexure I.
      • Similarly raise the temperature to 100 & 105ºC and record the observation on annexure I.
      • Acceptance Criteria: All the observed reading should be within limit of ±1°C.
      • Prepare the calibration tag and affix it with equipment.
      • Attach the old calibration tag with the record and do not throw it.
      • Frequency: 6 months ± 3 days.
      • If the variation is not within the specified tolerance limits:
        • Label the equipment with a tag, “OUT OF CALIBRATION”.
        • Inform the Department Head.
        • Do not use equipment until all errors are rectified. After rectification, again calibrate the equipment & record the observation.
      • Note: Vacuum Gauge & Temperature Controller is calibrated by external Agency at-least once in a six month.
  • Annexure (S)           


  • Reference (S)


  • Glossary

SOP            :    Standard Operating Procedure

QA              :    Quality Assurance

QC              :    Quality Control

ºC               :    Degree Celsius

mm             :    Millimeter

  • Revision History
Rev. No. Details of changes Reason for change

Bhanu Pratap Singh


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