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PARTLOW CHART EXERCISE

PARTLOW CHART EXERCISE. GENESIS. Introduced as a back up for manual recording of temperatures Works as a stand alone unit not requiring external power supply Mechanical clock winding mechanism provides drive for a rotating chart.

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PARTLOW CHART EXERCISE

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  1. PARTLOW CHART EXERCISE

  2. GENESIS • Introduced as a back up for manual recording of temperatures • Works as a stand alone unit not requiring external power supply • Mechanical clock winding mechanism provides drive for a rotating chart. • Provides continuous temperature recording for 31 days irrespective of power supply availability, whether container is empty or cargo loaded.

  3. Disadvantages • Provides only return temperature recording • Can be manually fudged – not 100% foolproof • Since it is a mechanical device, there is a little amount of sluggishness and hunting. • Prone to damage from external elements even though located in a protective enclosure • Needs regular calibration

  4. Subsequently replaced with Electronic datarecorder. • However some container owners still persist with Partlow Chart as it provides a readily readable record of temperature.

  5. Location of Partlow Mechanism and Sensor

  6. Partlow Chart Mechanism

  7. Fault Finding from Partlow Charts • Stylus contact on chart is not correct • System running with choked expansion valve passage or less refrigerant charge

  8. Fault Finding from Partlow Charts • Excessive Moisture in the Cargo Space • Compressor Tripped

  9. Partlow Chart Exercise-Chilled Cargo • Cargo Temp Setpoint: +8ºC • Date and Time of Plugging on board: 2nd noon • Temp at the time of plugging: 14ºC • Defrost Interval; 6 hours • Temp rise during Defrost: 3ºC • Start of Power Breakdown: 5th noon • Power restored: 5th midnight • Temp rise during power breakdown: 8ºC • Container Unplugged: 14th noon Draw a Partlow Chart based on the foll: data

  10. Partlow Chart Exercise-Chilled Cargo SOLUTION • Identify +8ºC on the Chart and draw a light circle representing Setpoint • Identify and mark 2nd noon and 14ºC to identify the time and temp at plugging • Draw the curve to reduce the temp to 10ºC in 6 hrs • Show a gradual increase of temp to 13ºC for max period of 2 hrs • At the end of 2 hrs show a sharp drop of temp to 10ºC in about 1 hr • Repeat the Defrost cycle after every 6 hrs. • From 5th noon till 5th midnight show a gradual rise of temp upto 18ºC

  11. Partlow Chart Exercise-Chilled Cargo SOLUTION Contd. • After power is restored at 5th midnight, show a rapid fall in temp upto12ºC in 6 hours when the next defrost cycle starts. • Repeat the defrost cycle for 2 hours showing temp rise of 3ºC • After the next defrost cycle show temp fall upto 10ºC in about 1 hr • Repeat the cooling and defrost cycle till 14th noon when the container is unplugged • Thereafter show a gradual rise in temp.

  12. Partlow Chart Exercise-Frozen Cargo Draw a Partlow Chart based on the foll: data • Cargo Temp Setpoint: -15ºC • Date and Time of Plugging on board: 18th noon • Temp at the time of plugging: -8ºC • Defrost Interval: 24 hours • Temp rise during Defrost: 4ºC • Start of Power Breakdown: 22nd noon • Power restored: 23rd midnight • Temp rise during power breakdown: 5ºC • Container Unplugged: 30th noon

  13. Partlow Chart Exercise-Frozen Cargo SOLUTION • Identify -15ºC on the Chart and draw a light circle representing Setpoint • Identify and mark 18th noon and -8ºC to identify the time and temp at plugging • Draw the curve to reduce the temp to -15ºC in 3 hrs • Maintain the same temp for about 24 hrs till the start of the first defrost cycle • Show a gradual increase of temp to -11ºC for max period of 2 hrs • At the end of 2 hrs show a sharp drop of temp to -15ºC in about 1 hr • Repeat the Defrost cycle after every 24 hrs. • From 22nd noon till 23rd noon show a gradual rise of temp upto -10ºC

  14. Partlow Chart Exercise-Frozen Cargo SOLUTION Contd. • After power is restored at 23rd noon, show a rapid fall in temp upto -15ºC in 2 hours and maintain it till the next defrost cycle starts. • Repeat the defrost cycle for 2 hours showing temp rise of 3 ºC • After the next defrost cycle show temp fall upto -15ºC in about 1 hr • Repeat the cooling and defrost cycle till 30th noon when the container is unplugged • Thereafter show a gradual rise in temp.

  15. SOLUTION

  16. Points to PONDER • For Chilled cargoes, the minimum temp recorded on Partlow Chart is 2-3ºC more than the Setpoint Temp whereas for Frozen cargoes, the minimum temp goes as low as the Setpoint Temp. WHY? • The max. Defrosting time is 2 hrs. WHY? • For Chilled cargoes, the rise is temp is faster than for frozen cargoes - both during defrosting time and also during power breakdown. WHY? • Defrosting interval is 6 hrs and 24 hrs respectively for chilled cargoes and frozen cargoes. WHY?

  17. IMPROVEMENTS ON PARTLOW CHARTS • Mechanical hand winding mechanism replaced by battery • Design with 2 sensors used for non-transport applications. • Electronic Partlow Recorders

  18. THANK YOU

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