Instruments & Controls

Safety of a facility may be improved by using interlock systems working in unison with hydrogen and fire detectors. Instrumented leak and flame detection systems should be integrated into the control systems such that when a hydrogen leak or a fire is detected they:

• Shut-off and isolate hydrogen sources
• Shut down/deactivate/deenergize process equipment to a safe mode
• Activate audible and visual alarms
• When applicable, increase active ventilation
• Require manual reset to restart

Remote notification of facility management and first responders should also be considered where appropriate.

Shutdown tables are sometimes used to document control actions resulting from specific events. Here is an example of a shutdown table:

Warning systems should be installed to detect abnormal conditions, malfunctions, and incipient failures. An alarm system (consisting of both audible and visible alarms) should be established, with distinctive signals used for each type of emergency. Practice drills should occur periodically to ensure that employees are familiar with the alarms and are trained at regular intervals about how to respond. The meanings of the various signals should be posted in all operational areas.

If no alarm system is provided in the facility, a means for notifying employees (e.g., a public address system) should be identified and practiced to ensure its adequacy during an emergency.

Leak Detector
(Pacific Northwest National Laboratory)