Oxygen Deficiency Hazards

ODH

SAF 103

Patty Hunt

Personnel will not enter or occupy areas in which oxygen concentration is less

than 19.5%

ODH - Oxygen Deficiency Hazards

POLICY

ODH training objectives1. Health Effects of ODH

2. ODH Hazards that can be Encountered at Jefferson Lab:

Cryogenic and Non Cryogenic Sources

3. Special Hazards from handling Ultracold Liquids

4. Jefferson Lab Controls for Cryogenic ODH:

•Identification and Classification of ODH Areas

•Worker Requirements for Entry into ODH Areas

•Engineering Controls Used to Reduce ODH Hazards

•Emergency Response Procedures

Training providesTHIS TRAINING DOES PROVIDE:

• qualification for entry to ODH 0 and ODH 1 areas

• retraining required every 12 months

ODH 2 AND HIGHER WORK REQUIREMENTS REQUIRE

• medical approval

THIS TRAINING DOES NOT QUALIFY YOU FOR

CONFINED SPACE ENTRY.

Visitor requirements

To bring a visitor into an ODH 0 or 1 area you must:

Have your supervisor’s permissionescort the visitor: one ODH qualified escort per visitorexplain the ODH hazards to the visitor before allowing them to enter the ODH area

TOUR GROUP REQUIREMENTS: OSP/TOSP

OSP

N2 vent

Manure pit

Nitrogen Bubble

Freon

1 Liter

400 times volume

Helium

1 Liter

1000 times volume

300 ft 3

Compressed Gas Cylinder

Argon

(See next slide)

Argon continued

A nitrogen spill from a CGCfills 300 cubic ft. or a room 10 ft. X 10 ft. 3 feet above floor level.

3 feet

10 ft.

10 ft

.

Compressed gas cylinder

Argon 6000 ft 3

Dewar

(See next slide)

Argoncontinued

10 ft.10

ft.

60 feet

A nitrogen spill from a dewar would fill a10’ X 10’ room 60 feethigh, covering 6000 ft3.

Gas shed

Site ODH Areas

Site ODH Areas

Test lab tank

Dewar service bldg

4 Important Properties of Cryogens

• Cryogens can liquify other gases.

• Cryogens can cause frost bite.

• Cryogens have high expansion ratio on vaporization.

explosion hazard

ODH hazard

• Cryogenic gases rise or sink depending on density.

Tunnel Endstation

Relay Rack

Counting House

Injector Service Bldg.

Electronic Relay Racks

Helium

25 Ft

TunnelCryomodule

Service Building

Helium Transfer Line

PPE

Helium Transfer Line

Pressure relief valves

Nitrogen small plume

Nitrogen large plume

Helium lintel

Lintel in tunnel

Exhaust duct

Closed penetration

Properties of GasSpecificDensity

Hydrogen .07Helium .14Neon .70Nitrogen .97

Air 1.00Oxygen 1.11Argon 1.39Carbon Dioxide 1.70Freon 4.35

Hazard Avoidance

WHEN ALARM SOUNDS:

EVACUATE

DO NOT ENTER PLUME

NOTIFY CREW CHIEF

TunnelCryomodule

Service Building

25 ft

Electric Relay Racks

Helium

Tunnel plume

Exit stairwell

Injector Service Building

Racks

Penetration

Penetration plume

Rack over penetration plume

N2 spill test

Spill ConclusionsAccelerator

• Tunnel is safe

• Lintels are working

• Service Buildings are safe

• Working with your head inside a relay rack is a hazard

• Service Building "plumes" are not visible for minor spills,

but are for major spills

End Stations

• Helium can only cause an ODH problem above the crane

Inside Hall A

Crane rail

CO2 Cylinders and Manifolds

CO2 fire extinguishing system discharges killing 2 workers

Switchgear looking west toward exit door Motor Generator Room

External Requirements - NFPA 12 - Carbon Dioxide Extinguishing Systems

• Warning signs at entryways to protected spaces and adjacent areas where the CO2 could migrate.

• All persons that can enter the space shall be warned of the hazards, given the alarm signal, and provided with safe evacuation procedures.

• The pre-discharge warning signal shall provide significant time delay to allow for evacuation under worst case conditions.

• All personnel shall be informed that discharge directly at a person will cause eye injury, ear injury, or even falls due to loss of balance upon impingement.

• To prevent accidental or deliberate discharge, a “lock-out” shall be provided when persons not familiar with the system are present in a protected space.

• Consideration shall be given to the possibility that personnel could be trapped or enter into an atmosphere made hazardous by discharge. Suitable safeguards shall be provided to ensure prompt evacuation, to prevent entry into such atmospheres, and to provide means for prompt rescue of any trapped personnel. Personnel training shall be provided. Pre-discharge alarms shall be provided.

Additional Information in NFPA 12, Appendix A indicates consideration should be given to:

Adequate aisleways and routes of exit kept clear at all timesNecessary additional or emergency lighting and directional signals to support quick safe evacuation.Only outwardly swinging self closing doors at exits with provisions for panic hardware as necessary.Continuous alarms at entrances until the atmosphere has been returned to normalOdor added to the CO2 so that such atmospheres can be recognizedWarning and instruction signs at entrances and within areasPrompt discovery and rescue of persons rendered unconscious in such areas (This can be accomplished by search by trained personnel with appropriate breathing apparatus immediately after discharge stops)Instruction and drills for all personnel within the area including maintenance construction personnel that may work in the area.Means for prompt ventilation of such areasOther steps or safeguards that are necessary to prevent injury or death based on careful study of each particular situationIt is recommended that SCBAs be provided for rescue purposes.