What sample compartment temperature improvements can be expected when using the "Auto-defrost" feature with H-Class and I-Class Sample Managers? - WKB23445

ENVIRONMENT

• ACQUITY H-Class Sample Manager - Flow Through Needle (SM-FTN)
• ACQUITY H-Class Bio SM-FTN
• ACQUITY I-Class SM-FTN
• ACQUITY I-Class Sample Manager - Fixed Loop (SM-FL)

ANSWER

• The auto-defrost feature mitigates the formation of ice in higher ambient and higher humidity environments.
  • When ice forms and the heater/cooler engine loses efficiency 
  • Gradually (if no user intervention), sample compartment temperature can rise above the 8 °C limit, unacceptable to users
• Auto defrost allows the engines heat sink to be operated at -2 °C versus previously maintained/controlled at 0.25 °C.
  • A colder heat sink temperature ensures lower in-compartment temperature performance 
  • Operating the heat sink at -2 °C increases risk of ice formation, leading to inefficiency and rising temperatures 
  • Auto-defrost addresses these risks by:
    1. Icing is mitigated with a 2-minute auto-defrost cycle that occurs once every 4 hours.
       • Users will observe a brief transient increase in compartment temperature during the auto defrost cycle, followed by compete recovery.
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    2. Minimize ice formation across the heat sink by reducing cooling power of the engine when the compartment door is open.
       • Users will observe a brief transient increase in compartment temperature (red) when the door is opened, followed by compete recovery.
       • 

ADDITIONAL INFORMATION

Requirements:

• ICS/Firmware: Update to Driver Pack 2018 R1 or newer
• Serial Number Cutoff:  Sample Managers with serial numbers of A17 or later contain the hardware for enabling auto-defrost capability.
  • Early model instruments may have been previously updated with proper engine/fan hardware by a Waters Field Service Engineer.

For more information, see the article " How to enable the auto defrost feature in H-Class and I-Class Sample Managers".