Safety and Hot Wire Foam Cutting

On Sun, 27 Feb 2005 04:09:13 -0500, Roger
wrote:

On Sat, 26 Feb 2005 02:13:30 GMT, Ernest Christley
wrote:

Stealth Pilot wrote:


polyurethane foam breaks down into phosgene gas under the heat of a
hotwire. dont hotwire it. use a knife and surform planer, or
sandpaper.

OK, so who uses polyurethane foam? The blue stuff I see hot wired is
polystyrene foam (Styrofoam (TM)) It gives off styrene which is not
healthy, but you have to get the wire way hotter than necessary to
cause it to break down into the nasty stuff.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com


polystyrene just gives off the expander gas trapped within each bead.

polyurethane is/was specified in mouldless construction for the more
structural areas of an aircraft.

afaik polystyrene doesnt break down in the way ascribed to
polyurethane foams.
Stealth Pilot

Dan, U.S. Air Force, retired wrote:

...

phos=B7gene (fos,j=8En, foz,-) n.a poisonous, colorless, very
volatile
liquid or suffocating gas, COCl2, used as a chemical-warfare
compound.
[1805-15; Gk ph=F4s light (contr. of ph=E1os) + -gen=81s -GEN]


Dan, U.S. Air Force, retired

Therfore you cannot get phosgene from hot-wiring polyurethane
since there is no Clorine in urethane (C3H7NO2).


It helps to look up the right thing:

http://www.asiapacific.noveoninc.com.../tpu/58238.htm

Hazardous Decomposition Products
Volatiles may be evolved during overheating, combustion,
ormdecomposition. These potential decomposition gases
have not been fullymdetermined but may include CO, CO2,

and small amounts of hydrogen CYANIDE,

oxides of nitrogen, hydrocarbons, isocyanates, water vapor
and/or combinations of the previous, and smoke. ...

(emphasis mine.)

http://electriccoop.apogee.net/res/reinure.asp

Urethane Insulation

Urethane insulation is made of plastic polymers and contains 80
to 90 percent closed cells containing refrigerant gas rather
than air. It is one of the most effective insulators, but is
flammable. When it burns it emits cyanide gas and is therefore
banned in some areas of the country.


(Note 'flammible' may be inappropriate as the autoignition
temperature for Urethane foams is well above the flashpoint
threshold for flammible _liquids_. 'Combustible' may be the
proper term but I don't know if those terms are used the same
way for solids as for liquids.)

Whereas phsogene kills you slowly cyanide is quite fast.

--=20

FF

wrote:

Dan, U.S. Air Force, retired wrote:


...

phos·gene (fos,jŽn, foz,-) n.a poisonous, colorless, very

volatile

liquid or suffocating gas, COCl2, used as a chemical-warfare

compound.

[1805-15; Gk phôs light (contr. of pháos) + -gen�s -GEN]


Dan, U.S. Air Force, retired


Therfore you cannot get phosgene from hot-wiring polyurethane
since there is no Clorine in urethane (C3H7NO2).


It helps to look up the right thing:

http://www.asiapacific.noveoninc.com.../tpu/58238.htm

Hazardous Decomposition Products
Volatiles may be evolved during overheating, combustion,
ormdecomposition. These potential decomposition gases
have not been fullymdetermined but may include CO, CO2,

and small amounts of hydrogen CYANIDE,

oxides of nitrogen, hydrocarbons, isocyanates, water vapor
and/or combinations of the previous, and smoke. ...

(emphasis mine.)

http://electriccoop.apogee.net/res/reinure.asp

Urethane Insulation

Urethane insulation is made of plastic polymers and contains 80
to 90 percent closed cells containing refrigerant gas rather
than air. It is one of the most effective insulators, but is
flammable. When it burns it emits cyanide gas and is therefore
banned in some areas of the country.


(Note 'flammible' may be inappropriate as the autoignition
temperature for Urethane foams is well above the flashpoint
threshold for flammible _liquids_. 'Combustible' may be the
proper term but I don't know if those terms are used the same
way for solids as for liquids.)

Whereas phsogene kills you slowly cyanide is quite fast.

I never said you could. I was answering a rather crude question.

Dan, U.S. Air Force, retired

Dan, U.S. Air Force, retired wrote:


I never said you could. I was answering a rather crude question.


Duly noted.

--

FF