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Alejo Bejemino

  Individual Last seen online, 3 years ago
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  • Joined 13 years ago
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  • Thank you, Jenny, for sharing the report and John for the comments.  These are very useful. We look forward that WHO PQS team and vaccine refrigerator manufacturers will consider these data for the improvement and development of existing and future cold chain equipment. Other LMICs may have the same problems but were not documented.  Hope similar study will be extended to other LMICs.  

    Please find a summary table of some important aspects mentioned in the report and comments namely: 1) power supply source, 2) voltage stabilization, 3) refrigeration system, 4) holdover, and 5) temperature monitoring.   Remarks and commentsmay be used for improvement and development of future vaccine refrigeration equipment.

    Power supply source 

    Voltage stabilization

    Refrigeration system

    Holdover (Passive cooling)

    Temperature monitoring

    Remarks/Comments

    1. On-grid

    a) within ±10% of nominal value

    Not required but useful if installed

    Electric...

    Thank you, Jenny, for sharing the report and John for the comments.  These are very useful. We look forward that WHO PQS team and vaccine refrigerator manufacturers will consider these data for the improvement and development of existing and future cold chain equipment. Other LMICs may have the same problems but were not documented.  Hope similar study will be extended to other LMICs.  

    Please find a summary table of some important aspects mentioned in the report and comments namely: 1) power supply source, 2) voltage stabilization, 3) refrigeration system, 4) holdover, and 5) temperature monitoring.   Remarks and commentsmay be used for improvement and development of future vaccine refrigeration equipment.

    Power supply source 

    Voltage stabilization

    Refrigeration system

    Holdover (Passive cooling)

    Temperature monitoring

    Remarks/Comments

    1. On-grid

    a) within ±10% of nominal value

    Not required but useful if installed

    Electric compression using digital inverter compressor

    ILR with at least 120 hours holdover

    30 DTR

    RMTD

    WHO PQS compliant refrigerators and freezers have varied holdover at different vaccine storage capacity.  Holdover to at least 120 hours will ensure vaccine protection when power supply becomes intermittent.

    Almost all designs of vaccine refrigerators/freezers are electric compression with the following features: 

    *single speed, 

    *start and stop at preset thermostat setting.

    *need high starting current to start motor

    *noisy operation

    Latest electric compressor design has the following features:

    *digital inverter 

    *multi speed *compressor does not stop but adjust its speed based on heat load requirements. No need for frequent start and stop of motor compressor 

    *upfront cost is high but can be recovered by savings in electricity

    *quiet operation

    b) fluctuating voltages

    Extended voltage stabilizers

    Digital inverter compressor

    ILR with at least 120 hours holdover

    30 DTR 

    RMTD

    Same remarks/ comments as above

    c) extreme voltages: low (undervoltage) and high (overvoltage) 

    Voltage stabilizers to automatically shut off

    Refrigerant compressor and electronic control automatically shut off

    ILR with at least 120 hours holdover

    30 DTR

    Voltage stabilizers and compressor to shut off at extreme conditions to prevent damage to both

    2. SDD

    Not required

    Digital inverter compressor or purely 12/24V DC compressor

    SDD with at least 5 days autonomy 

    30 DTR

    Continuous operation during daytime but switch off at night

    3. Hybrid 

    a) electricity (with fluctuating voltages) and SDD

    Extended voltage stabilizers

    Single digital inverter compressor 

    ILR with at least 120 hours holdover

    30 DTR

    Electricity (AC) and Solar (DC) goes to the grid to power the digital inverter compressor.

    b) electricity (with fluctuating voltages) and SDD

    Extended voltage stabilizers

    Dual compressors with dual refrigeration system

    ILR with at least 120 hours holdover and SDD with at least 5 days autonomy 

    30 DTR

    At nighttime digital inverter compressor will operate.

    At daytime when electricity is fluctuating SDD will operate.

    4. Both power sources are not available

    Not applicable

    Not applicable

    Use freeze free cold boxes with cold life of at least 30 days

    30 DTR

    Freeze tag

    Replacement of melted icepacks has to be done on regular basis

    Hope these are useful.  

    Alejo H. Bejemino

    Consultant

    Cold chain and Vaccine Management

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  • Thank you for the document on “Decommissioning and safe disposal of cold chain equipment”.  This is very useful and will surely assist countries in the decommissioning and safety disposal of their obsolete cold chain equipment.

    Here are some observations which may be used to improve the document:

    1. There is no statistics on the number of absorption refrigeration units used in health centers around the world. Based on work experience in underdeveloped and developing countries, EPI activities (since the start of the program) were sustained using absorption refrigerators (kerosene or lp gas fueled systems). With the emergence of new and more efficient technologies, absorption refrigerators were gradually phased out from the immunization system.  The guidance document should include some actions on what to do with these absorption units that are functional but are obsolete. Most of these units are still charged with ammonia, water and hydrogen.  Is it safe to vent or release...

    Thank you for the document on “Decommissioning and safe disposal of cold chain equipment”.  This is very useful and will surely assist countries in the decommissioning and safety disposal of their obsolete cold chain equipment.

    Here are some observations which may be used to improve the document:

    1. There is no statistics on the number of absorption refrigeration units used in health centers around the world. Based on work experience in underdeveloped and developing countries, EPI activities (since the start of the program) were sustained using absorption refrigerators (kerosene or lp gas fueled systems). With the emergence of new and more efficient technologies, absorption refrigerators were gradually phased out from the immunization system.  The guidance document should include some actions on what to do with these absorption units that are functional but are obsolete. Most of these units are still charged with ammonia, water and hydrogen.  Is it safe to vent or release ammonia gas to the atmosphere or it is safe to bury by encapsulation the entire absorption refrigerator/freezer?  Venting the fluids from the absorption refrigeration system will cause no harm to the environment as ammonia has zero ODP and zero GWP. However, ammonia is very toxic and a health hazard to technicians who handle them.  It is of utmost importance to provide guidance for the proper, safe disposal, and management of risks in handling ammonia gases.
    1. Many old CFC or HCFC refrigerators and freezers are still charged with refrigerant gas but are not efficient and are obsolete thus need to be replaced. Many countries do not have service equipment and trained staff to remove or recover the refrigerant and oil from the refrigeration system. Thus, the need to provide training in good service practices and necessary equipment for recovery and safety of technicians.  Most of the new cold chain equipment are provided by GAVI, UNICEF, WHO and other international organizations.  They could also include some funding for the training and procurement of related service equipment.
    1. Recovered refrigerant, compressor oil and other contaminants from the refrigeration unit have to be kept in a sealed container and have to be disposed of properly to prevent contamination of the environment.An agency who has the capacity to handle these wastes disposal should be designated in every region.WHO, UNICEF, GAVI and other stakeholders may provide financial and technical assistance to these countries in order to protect the environment from ozone depletion and global warming effects.

    Hope these are useful.

    Alejo H. Bejemino

    Cold Chain and Vaccine Management Consultant

     

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