Handling/Maintenance of Water Electrolysis Cell Stacks – Avoiding Electrical Discharge
Water electrolysis bipolar cell stacks are composed of many individual electrochemical cells in electrical series. In practice, water electrolysis cell stacks that have just been stopped can retain a significant electrical charge due to residual hydrogen and oxygen remaining within each cell. Left alone, it may take many hours for this residual electrochemical charge to dissipate. System service and maintenance personnel must exercise extreme caution if attempting to service or replace these cell stacks soon after operation. For instance, a metal tool such as a wrench could inadvertently bridge a gap between a cell stack positive current terminal plate and an earth-grounded metal support frame, drawing a large current or an electrical arc with damage and injury as an unwanted result. Personnel not wearing appropriate insulating protective equipment are at risk as well.
Best practice for maintenance and service personnel is to verify that no significant electrical charge remains in the cell stack before removing safety guards and electrical connections from the cell stack. Personnel are advised to perform a cell stack voltage measurement to verify that the cell stack is discharged. In some cases, service personnel may also apply a properly designed service tool composed of a high-current shorting resistor across the discharged cell stack as an additional safeguard.
CGA G5.5, Hydrogen Vent Systems
CHS Webinar: Safety of Water Electrolysis
CSA/ANSI 22.2 No. 22734 (to be published in 2023)
EIGA Doc 154 09 E, Safe Location of Oxygen and Inert Gas Vents
EIGA Doc 211 17, Hydrogen Vent Systems for Customer Applications
IEC 61010-1, Safety requirements for electrical equipment for measurement, control, and laboratory use - Part 1: General requirements
ISO 22734, Hydrogen generators using water electrolysis — Industrial, commercial, and residential applications (current version 2019)
ISO/TR 22734-2, Hydrogen Generators Using Water Electrolysis – Part 2: Testing guidance for performing electricity grid service (to be published in 2023)
NFPA 2, Hydrogen Technologies Code