CHM 605

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CHM 605

• Gas Safety Electrical Safety

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Tables of Contents

• Electricity
• voltage/current
• recepts/switches
• cords
• tools
• equipment
• shutoffs
• procedures

• Gas Safety
• compressed gases cryogenic liquids
• hazards
• storage, handling transportation
• regulators
• teflon tape

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Gas Safety

• We will discuss both compressed gases and
  cryogenic liquids.

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Gas under pressure

• is an energy hazard
• there are often chemical hazards too, but the
  energy hazard is NONTRIVIAL.

http//www.disastercity.com/n2cylder/
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Acetylene Toyota
This was a combination chemical hazard PLUS
pressure issue
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Pressurized Gas Hazards

• physical force -- gas propelled rocket (if the
  valve becomes damaged).
• simple asphyxiation (oxygen displaced)
• chemical hazards, e.g. flammability, reactivity,
  burns
• health hazards, e.g., toxicity, mutagenicity

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Nomenclature

• cylinder and bottle both used to describe
  many gas containers.

• valve commonly means the main handwheel (which
  is an ON-OFF switch really)
• cap screws onto threads at base of valve
• regulator attachment (essential) allows
  careful delivery of gas

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diagram
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See Gas Safety Handout

• label
• secure
• cap
• move with cart

• leaks?
• temperatures?
• protection from damage
• hydrostat test date

• details

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Regulators

• Not optional
• No substitutions
• No grease
• See also
• Aldrich Tech Bulletin AL-151
• Air Products Safetygrams

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Teflon tape?

• DO NOT use teflon tape on CGA or compression
  fitting threads.
• Do tape NPT threads (three layers of PTFE tape).

(NPT National Pipe) Thread (CGA Compressed
Gas Association)
Did you receive Gas Cylinder Safety handout?
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Gas-tight lines

• Gas delivery at gt 1 atm must be via metal tubing
  put together correctly.
• Swagelok Installers Manual gives good info about
  gas tight lines (also vacuum tight).
• http//www.swagelok.com/
• http//www.chem.purdue.edu/chemsafety/Chem/SwageLo
  kPocketInstallerGuide.pdf

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Liquefied Gas

• High strength magnets in NMR and MRI use helium,
  which presents quench hazard.
• "Quench" rapid and violentboil-off of gas
• Be readyto evacuate to avoid asphyxiation
  and/or frostbite.
• (Asphyxiation is forever.)

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The most commonly reported

• injury related to cryogen use is
• (a) broken bone(s)
• (b) back sprain/strain
• (c) tissue damage (cold burn)
• (d) hearing loss
• (e) asphyxiation

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Liquefied Gas Hazards

• Extreme Cold
• Asphyxiation
• Toxic Hazards (sometimes)
• Obscured Vision
• High Pressure (if system sealed)
• High Magnetic Fields
• Liquid Oxygen..

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Try to never condense O2

• If liquid nitrogen is left in cold trap
  overnight. And system is open to allow air in..
  O2 will condense into the coldfinger.

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Part II - Basic Electrical Safety

• For lab staff and the people who work near them.

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"It's not the voltage ...

• ... that kills you, it's the current."
• True or False?
• Both?
• Why do people say this?

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Current

• More than 3 ma
• painful shock
• More than 10 ma
• muscle contraction no-let-go danger
• More than 30 ma
• lung paralysis- usually temporary
• More than 50 ma
• possible ventricular fib. (heart dysfunction,
  usually fatal)
• 100 ma to 4 amps
• certain ventricular fibrillation, fatal
• Over 4 amps
• heart paralysis severe burns. Usually caused by
  gt600 volts

REMEMBER THESETWO
REMEMBER THESETWO
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Switch

• and cover plate
• we take for granted
• we miss it if its not there

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Receptacle

• Recept, outlet, socket, plug-in
• and cover plate.
• This one is GFCI, required in many wet
  applications.

GFCI ground fault circuit interrupt
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Plug

• Whats hot?
• Whats not?
• Whats missing in this picture?

(This plug is not polarized -- one prong larger
than the other, nor does it have a grounding
prong.
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Cords - always check for damage
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(No Transcript)
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Tools and Equipment

• Inspect power cords for damage (replace, never
  repair with electrical tape)
• Inspect tools and equipment
• Inexpensive devices exist for safely testing for
  grounding and for finding a break in a circuit.

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Note

• Circuit Breakers
• Provided to protect EQUIPMENT not people
• Do not reset a breaker (or replace a fuse) until
  you know why it tripped
• Breaker box is your emergency shutoff.
• GFCIs
• Provided to protect people
• Trip range 4-6ma
• Monthly test

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Circuit panel ("service panel...")

• Do not ever block panel.
• Know where to shut it all off.
• In a hurry.
• Without having to move anything out of the way
  first.

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Standard Operating Procedures

• For any work involving design or construction of
  electrical equipment, standard procedures must
  exist and be followed.

• SOP
• This is supposed to be a mock-up of a standard
  operating procedure for design or construction of
  electrical equipment or elements.
• My plan is to make the text so tiny that it will
  not be at all possible to read, not by anyone in
  the audience or anywhere I could paste in some
  DOT hasmat table, or the paragraphs leading up to
  the table...
• A. But Instead I think I'll paste in some stuff
  from The web pages here and there. Enchilada
  tourney was originally started on the old
  Kilbassa site, but since it was almost complete,
  we decided to finish it here. We are currently in
  the finals, so if you want to see how your
  friends are doing, go to the Tourney Results Page
  B. It must be the season for 'puter problems
  (ain't it always!) but my monitor seems to be
  wearing out- after 12 years / So if I miss a few
  days - please be patient my friends. Kat
  11/17/1999 854 am EST
• C. It must be the season for 'puter problems
  (ain't it always!) but my monitor seems to be
  wearing out- after 12 years / So if I miss a few
  days - please be patient my friends. Kat
  11/17/1999 854 am EST It must be the season for
  'puter problems (ain't it always!) but my monitor
  seems to be wearing out- after 12 years / So
  if I miss a few days - please be patient my
  friends. Kat 11/17/1999 854 am EST It must be
  the season for 'puter problems (ain't it always!)
  but my monitor seems to be wearing out- after
  12 years / So if I miss a few days - please be
  patient my friends. Kat 11/17/1999 854 am EST

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Electrical Safety Handout

• Use it. Ask questions.

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THANK YOU