2.  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.  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.

7.  Stylus contact on chart is not correct  System running with choked expansion valve passage or less refrigerant charge

8.  Excessive Moisture in the Cargo Space  Compressor Tripped

9. º 1. Cargo Temp Setpoint: +8ºC 2. Date and Time of Plugging on board: 2 nd noon º 3. Temp at the time of plugging: 14ºC 4. Defrost Interval; 6 hours º 5. Temp rise during Defrost: 3ºC 6. Start of Power Breakdown: 5 th noon 7. Power restored: 5 th midnight º 8. Temp rise during power breakdown: 8ºC 9. Container Unplugged: 14 th noon Draw a Partlow Chart based on the foll: data

10. º  Identify +8ºC on the Chart and draw a light circle representing Setpoint º  Identify and mark 2 nd noon and 14ºC to identify the time and temp at plugging º  Draw the curve to reduce the temp to 10ºC in 6 hrs º  Show a gradual increase of temp to 13ºC for max period of 2 hrs º  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. º  From 5th noon till 5 th midnight show a gradual rise of temp upto 18ºC SOLUTION

11. º  After power is restored at 5 th midnight, show a rapid fall in temp upto 12ºC in 6 hours when the next defrost cycle starts. º  Repeat the defrost cycle for 2 hours showing temp rise of 3ºC º  After the next defrost cycle show temp fall upto 10ºC in about 1 hr  Repeat the cooling and defrost cycle till 14 th noon when the container is unplugged  Thereafter show a gradual rise in temp. SOLUTION Contd.

12. º 1. Cargo Temp Setpoint: -15ºC 2. Date and Time of Plugging on board: 18 th noon º 3. Temp at the time of plugging: -8ºC 4. Defrost Interval: 24 hours º 5. Temp rise during Defrost: 4ºC 6. Start of Power Breakdown: 22nd noon 7. Power restored: 23rd midnight º 8. Temp rise during power breakdown: 5ºC 9. Container Unplugged: 30 th noon Draw a Partlow Chart based on the foll: data

13. º  Identify -15ºC on the Chart and draw a light circle representing Setpoint º  Identify and mark 18th noon and -8ºC to identify the time and temp at plugging º  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 º  Show a gradual increase of temp to -11ºC for max period of 2 hrs º  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. º  From 22nd noon till 23 rd noon show a gradual rise of temp upto -10ºC SOLUTION

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

16. º  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.  Mechanical hand winding mechanism replaced by battery  Design with 2 sensors used for non-transport applications.  Electronic Partlow Recorders