Compressed Gas Safety: Emergency Planning & Response

As a Reminder…

PIs, core facilities directors, and other managers are obligated to:

  • Ensure that personnel under their supervision are appropriately trained and that adequate safety controls are in place before work with hazards is commenced.
  • Maintain ongoing safety management, which includes being aware of activities taking place in their facilities, monitoring safety practices, and correcting safety non-compliances through re-training or other appropriate measures.

Staff, students, and other users are obligated to:

  • Adhere to safe work practices communicated to them through trainings, lab safety rules, and SOPs.
  • Communicate safety concerns to their manager/supervisor, including prompt reporting of any incidents or near-misses.

Sections

Safety Controls and Emergency Planning Overview

The following are typical safety controls for reducing the adverse consequences of an emergency:

Engineering Safety Controls

  • Emergency shutoff (manual or automatic)
  • Automatic fire suppression system
  • Emergency exhaust
  • Over-pressure relief
    • Relief valves
    • Bursting discs
  • Blast shield
  • Other safety controls
    • Gas alarms
    • Flame detector

Administrative Safety Controls

  • Emergency response plan incorporated into an SOP
    • Review annually and update as needed (e.g., procedural changes, emergency contact information)
  • Initial and refresher emergency response training
  • Signage and labeling
    • Signage in conspicuous areas that outline basic details of emergency response and notification (e.g., what to do if gas-related alarm sounds)
    • Clear signage/labeling of emergency shutoff valves and other emergency-critical controls and equipment

Personal Protective Equipment (PPE)

  • Last line of defense in the event of an uncontained emergency.
  • Basic PPE: lab coat, safety glasses (or goggles if there is a splash hazard), disposable nitrile gloves
  • Additional PPE which may be required for higher-hazard gas systems:
    • Hearing protection, in case of expected or unexpected high-pressure gas venting
    • Face shield (worn over splash goggles or safety glasses) if there is a significant projectile hazard.
    • Flame-resistant gloves
    • Respiratory protection. NOTE: Engineering safety controls (e.g., ventilation systems, gas cabinets, fume hoods, and cross-purge setups) should always be used to eliminate airborne exposure hazards, obviating the need for respiratory protection. 
      • Special regulations apply — Use of respiratory protection is governed by the USC Respiratory Protection Program.
      • Requests for respiratory protection are subject to EH&S assessment before approval.

Emergency Plans

General guidelines and considerations are provided below to aid in developing an emergency response plan for your gas SOP. Tailor the SOPs to your specific gases, equipment, and facilities.

Note that having a good emergency response plan does not lessen the need to implement adequate engineering, administrative, and other safety controls to minimize the probability of a safety incident occurring.

Types of Hazards/Failures

Assess potential failure modes and consequent hazards for the specific gas/equipment/procedures. Focus on failure modes that are relatively probable (e.g., from simple operator errors) as well as those which give rise to serious hazards.

Remember, when assessing risk, consider both the likelihood and adverse impact of potential events.
Fundamental failure modes of gas systems are as follows:

  • Leaks. Depending on the gas, the pressure, presence or absence of flow restrictions, etc., the hazard might range from zero to IDLH (immediately dangerous to life or health). Hazards may include:
    • Oxygen deficiency
    • Toxicity
    • Flammability
    • Formation of explosive atmosphere
    • Corrosivity
    • Loud sound sufficient to cause hearing damage
  • Vessel or pipework explosive failure. This might be due to direct over-pressurization, or indirect overpressure arising from a chemical reaction or gas ignition within the system. Explosive failure may also result from mechanical damage, corrosion, or the system having an insufficient pressure rating due to flaws in design or construction. Hazards may include:
    • ExplosionProjectilesFire
    • All hazards listed under Leaks

The above fundamental failure modes have many variations and root causes specific to the particular system being risk-assessed. The system owner/manager (e.g., PI) is ultimately responsible for ensuring adequate assessment of risk. Where hazards are unusually high (e.g., toxic gases or high working pressure), or complex systems are involved, it may be necessary for the system owner or manager to hire a qualified consultant to design the appropriate safety controls if adequate expertise is not available in-house.

Hazard Recognition

Users need to be trained on how to recognize a potentially hazardous non-routine situation. A failure such as a major leak or explosive vessel failure is difficult to miss. Others may not be directly discernible by human senses, in which case an appropriate alarm system may be needed. It is highly recommended to incorporate details of hazard recognition pertinent to the particular gas and system into SOPs.

Hazard identification techniques may include:

  • Inspection
    • Visible damage
    • Leak testing
    • If a system requires routine inspection (e.g., before every use), record the appropriate inspection procedure in the SOP and log each inspection in a logbook or checklist.
  • Sounds e.g., abnormal hissing
  • Alarm activation
    • Gas detection alarm — toxic gas, flammable gas, high CO2
    • Low oxygen alarm
    • Fire alarm e.g., UV/IR flame detector for hydrogen (which burns with an almost invisible flame)
    • Loss-of-exhaust alarm
  • Physiological effects
    • Odor
    • Irritant properties
    • DO NOT design safety controls with physiological effects as a primary warning method!
  • Loss-of-exhaust
    • Audible alarm when a monitored exhaust ventilation system (e.g., chemical fume hood) is interrupted. It is also important to consider the following:
      • Legacy systems may not be alarmed
      • Alarms may not be calibrated or fully functional
    • Check mechanical exhaust indicator (e.g. Vaneometer™) before starting as a required work practice.
    • Train users to respond to other indicators, e.g., unusual sounds/lack-of-sound from ventilation system.
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Emergency Response

Build emergency response procedures into the SOP that are appropriate and specific for the facility. Procedures may include a combination of the following:

Situational Assessment

  • Determine the nature of the emergency from a safe location.
  • Remote access to gas alarms and systems provides critical diagnostics.

Alert and Evacuate

  1. For severe hazards or uncontrollable situation, notify all personnel to evacuate the area.
  2. Activate fire alarm if building evacuation seems warranted.
  3. Call DPS relaying the nature of the emergency.
  4. Remain in the vicinity of the building, to provide information to first responders.

Gas Fire

  • Turn off gas supply only if safe to do so.
  • If gas supply cannot be stopped, extinguishing the fire may result in a more hazardous situation
    • Escaping unburned gas may build up and cause an explosion
    • Evacuate, activate fire alarm, and call DPS
    • Remain on site to inform first responders.

Fires Impinging on Gas Cylinder

  • The cylinder can heat up and potentially explode if in close proximity to an active fire.
  • If the fire is small and burning for a very short time, attempt to extinguish if it is safe to do so. Otherwise, evacuate the area, activate the fire alarm and call DPS.
  • All other fires
    • Extreme danger of explosion!
    • Do not attempt to extinguish.
    • Evacuate, activate the fire alarm, and call DPS.

Hazardous Atmospheres

  • Low O2/High CO2
    • If a low oxygen or high carbon dioxide alarm sounds, IMMEDIATELY evacuate the area and close all doors behind you. If any personnel become unconscious, DO NOT attempt a rescue as you will likely become another victim. Remember, oxygen deficiency is not clearly sensed by humans and may cause loss of consciousness suddenly with no prior symptoms or warning.
    • Call DPS relaying the nature of the emergency.

Gas Leaks

The response to gas leaks is largely dependent on the material that is being used or stored and whether the leak is an accidental release or contained within an exhausted enclosure.

  • Toxic gases
    • Evacuate and call DPS
    • Owners (PI, School) of toxic gas systems are responsible for implementing a response protocol to their gas alarms, including having on-call personnel.
  • Flammable gases
    • Small leak
      • In well-ventilated normal sized spaces, small leaks are not likely to build up and create an explosive atmosphere; however, a small leak can still result in a localized fire if an ignition source is present.
      • Leaks in confined spaces are more likely to build up and create an explosive atmosphere and ignite.
      • If safe to do so, turn off cylinder valve.
    • Major leak
      • If the gas supply can be quickly cut off from a safe remote position, then do so. If not, immediately evacuate, activate fire alarm, and call DPS.
    • Hydrogen
      • Poses unusually high fire and explosion risks
        • Wide flammability range in air
        • High flame velocity and mixtures with air readily transition to supersonic detonation
        • Extremely low ignition energy — often ignites/explodes “spontaneously” from miniscule sparks of static electricity
        • A high-pressure stream of hydrogen discharged into air often ignites spontaneously
        • Hydrogen flames are nearly invisible, raising the risk of contact and burns
      • Approach with great caution when responding to a hydrogen leak.

Catastrophic Failure/Explosive Depressurization

Immediately evacuate and call DPS.

First Responder Coordination

  • Inform first responders of the type of gas and provide Safety Data Sheets (SDS), if known.
  • Describe incident and actions taken, if any, to the best of your ability.
  • Comply with any additional instructions given by emergency responders.
  • Remain on-site until confirmed that the situation is under control and your presence is no longer required.
  • Leave your name and phone number with responders before leaving. Be prepared to answer your phone in case follow-up calls are made by responders or EH&S.

Incident Reporting and Seeking Medical Attention

  • If emergency medical assistance is needed, call DPS and request an ambulance.
  • If non-emergency medical attention is required (e.g., urgent care), consult the Emergency Notification and Incident Reporting web page for instructions.
  • Ensure your PI completes and submits a completed managers’ report of incident at the earliest opportunity.
  • Notify EH&S. EH&S may follow up with an incident investigation to determine root cause, provide pertinent safety documents, and suggest tools, techniques, and best practices to prevent similar incidents in the future.
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