Rules for storing and working with dangerous gases can be found in the Section on Process Safety

General Rules for Handling Gas Cylinders
  • All compressed gas cylinders shall be secured with chain or strap between the “waist” and “shoulder of the cylinder at all times.  This includes empty cylinders.
  • Cylinders not currently in use must be capped. (“in use” includes cylinders connected to equipment or processes used at least 3 times per week)
  • Empty cylinders must be capped

Limit the number of cylinders in the lab by keeping no more than 1 back up cylinder for every cylinder in use (may exclude flammable gases, see GT Dangerous Gas Safety Program)

  • Cylinders must be kept away from electrical wiring where the cylinder could become part of the circuit.
  • Store cylinders in well-ventilated areas designated and marked only for cylinders.
  • Store cylinders in an upright position (includes lecture bottles).
  • Empty cylinders should be clearly marked and stored as carefully as those that are full because residual gas may be present.
  • Mark empty cylinders EMPTY
  • Keep valves closed on empty cylinders.
  • Protect  cylinders from corrosive vapors and sources of heat
  • Do not store cylinders in egress areas near emergency exits, hallways, or under stairs.
  • Do not keep cylinders more than 5 years past their hydrostatic test date (see receiving cylinders, below).
Receiving Cylinders
  • Inspect all cylinders upon delivery for valve protection and hydrostatic test date, which should be within the past 5 years.  The hydrostatic test date will be stamped into the collar of the cylinder.  A stamp of 2MM84+ indicates that the cylinder was last hydrostatically tested in February of 1984; “MM” are the inspector’s initials: “+” indicates that it is authorized for charging up to 10% in excess of its marked service pressure.  Retest stamps should also appear on the neck or shoulder of the cylinder : 4L02* means that the cylinder was re-tested in April of 2002 at facility “L”.  A star after this number means that the cylinder has a 10 year retest cycle, rather than a 5 year cycle.
    •  Do not accept the cylinder past it’s hydrostatic test certification
    • Do not keep a cylinder past its hydrostatic test certification.  (This is due to Department of Transportation regulations- it is not legal to transport a cylinder that is out of date, so technically, the gas supply company can’t remove it if it is out of date.)
  • Check the cylinder’s service pressure.  This will be found on the collar opposite the hydrostatic test stamp.  This stamp will have 3 lines and may look something like this:

 DOT3AA2265

K16110

BTWECO

  • The first line  means that the cylinder meets US Department of Transportation Specification 3AA and has a service pressure of 2265 psig at 70 degrees F
  • The second line is the manufacturer’s serial number
  • The third line is the manufacturer’s unique symbol
    • Do not accept cylinders unless they are clearly labeled as to their contents. NEVER rely on cylinder color as an indicator of the cylinder’s contents

Cylinder caps and valves should not require anything more than hand pressure to open- do not accept the cylinder if this is not the case.

Cylinder Storage: Chemical Compatibility

Cylinders must be stored in compatible groups:

  • Flammables from oxidizers:  Keep oxygen cylinders a minimum of twenty feet from flammable gas cylinders or combustible materials. If this can not be done, separation by a non-combustible barrier at least 5 feet high having a fire-rating of at least 0.5 hours is required.  NOTE This applies to cylinders in use, “back up” cylinders stored in labs, and “empty” cylinders.
  • Corrosives from flammables or oxidizers  (20 feet in outdoor storage area; does not apply when cylinders are indoors in gas cabinets) NOTE corrosive gas cylinders are not allowed indoors unless they are in gas cabinets.
Moving/Transporting Cylinders
  • Never move a cylinder that is not capped.
  • Always use a cylinder cart to move cylinders from place to place, do not roll or “twirl” them from one place to another.
  • Don't use the protective valve caps for moving or lifting cylinders.
  • Don't drop a cylinder, or permit them to strike each other violently or be handled roughly.
  • Moving cylinders and dewars on elevators
    • Whenever possible use freight elevators
    • Do not allow other people to ride the elevator with the gas cylinder- politely ask them to wait for the next elevator.

Here’s a demonstration of what can happen when an un-capped cylinder is damaged: http://www.youtube.com/watch?v=ejEJGNLTo84

Same thing- a safety issue for all you SCUBA divers out there: http://www.youtube.com/watch?v=tyINNUaXa8Q&NR=1

Not for the faint of heart regarding a portable-sized oxygen cylinder: http://www.youtube.com/watch_popup?v=9lw_fhNAIQc#t=160

Labeling Cylinders
  • The cylinder, not the cap, must be labeled as to the contents and supplier.  Do not rely on cylinder color to identify cylinder contents: color coding is not universal and varies from one supplier to another.
  • Cylinder labels must be facing out so as to be visible to lab inspectors and emergency responders.
  • EHSA labels for gas cylinders should be affixed to the wall (preferable) or kept in a note book in the lab.  Gas cylinders use the “green label” system for high through-put chemicals: the label stays on the wall, even when the gas cylinder is changed out. There is no requirement to remove the old cylinder from the system and re-enter the new cylinder every time the cylinder is changed out as long as the replacement cylinder has the same contents as the original.  
Cylinder Fittings/Gas Tubing
  • Cylinder fittings vary between gas types, inert, oxidizing, corrosive, and flammable.
  • Never use grease or Teflon tape to force a fitting- you may be putting together two types of incompatible fittings.
  • Always use non-sparking tools (brass or aluminum) to work on flammable or oxidizing gas fittings.
  • Fittings and tubing must be compatible with the gas. See the GT Dangerous Gas Safety Program for compatibility information. 
  • Flammable and poison gases may only be used with stainless steel tubing.   
 Regulators
  • Must be marked for the maximum cylinder pressure.  Cylinder pressure may not exceed 75% of the regulator’s maximum rated pressure
  • Must be equipped with two gauges: one to show the cylinder pressure and the other to show the outlet pressure. An exception to this is single stage regulators used for corrosive gases.
  • Never use an adapter between the regulator and the source cylinder
  • Never use an aid, such as Teflon tape to connect a regulator to a cylinder.
  • After attaching a pressure-reducing regulator to a compressed gas cylinder
    • Turn the regulator adjustment screw out (counterclockwise) until it feels loose
    • Stand behind the cylinder with the valve outlet facing away from you and observe the high pressure gauge on the regulator from an angle, never pressurize a gauge while looking directly at it.
    • Open the valve handle on the gas cylinder slowly until you hear the space between the cylinder valve and regulator fill with gas. (You can also watch the pressure rise on the high pressure gauge.  If you turned the adjustment screw properly, there should be no gas flow out of the regulator and no pressure rise on the low-flow pressure gauge. 
    • When you are ready to use the cylinder, open the valve until you feel it stop, then turn it back one-quarter turn.
    • If the regulator does not come with a hand wheel, the wrench needed  to open it must be left at the cylinder so that it can be closed quickly in the event of an emergency.

Cylinder Use

Be sure all connections are tight. Use soapy water to locate leaks. See the Dangerous Gas Safety Program for leak testing on dangerous gas systems.

  • Keep cylinders valves, regulators, couplings, hose and apparatus clean and free of oil and grease.
  • Keep cylinders away from open flames and sources of heat.
  • Safety devices and valves shall not be tampered with, nor repairs attempted. Use flashback arrestors and reverse-flow check valves to prevent flashback when using oxy-fuel systems.
  • Regulators shall be removed when moving cylinders, when work is completed, and when cylinders are empty.
  • Cylinders shall be used and stored in an upright position
  • The cylinder valve should always be opened slowly. Always stand away from the face and in back of the gauge when opening the cylinder valve.
  • When a special wrench is required to open a cylinder or manifold valve, the wrench shall be left in place on the valve stem when in use; this precaution is taken so the gas supply can be shut off quickly in case of an emergency; and that nothing shall be placed on top of a cylinder that may damage the safety device or interfere with the quick closing of the valve.
  • Fire extinguishing equipment should be readily available when combustible materials can be exposed to welding or cutting operations using compressed cylinder gases.
  • Welding and cutting operations in labs require a Hot Work Permit

The purchase and use of dangerous gases fall under the Georgia Tech Dangerous Gas Safety Program.

  •   Please review this program before purchasing ANY quantity or concentration of dangerous gases to ensure that you are handing the material per Georgia Tech rules and State Fire Codes