Document RJ8q9NxYnwr653NL3vydpy1rz
K/
A OMUMCNT CCNTCR luff Technical Import #210
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By
D*t Ccaplttod:
N. ft. O'MM 0. A. Ihi
January 16, 1970
oat* issued: Jeauary 23, 1970
DISTRIBOTIOft
Akron Qenersl Chemical Want ^F.T.Uhltalre-R.S.Reynolds
Akron Legal Dept.
B.K.Bean Aeon Lake General chemical Flint
*R.I.Rylands-R.tf.HcEsy j.H.Wkitney
Brecksellle fteseareh Center ft. I. Banala R.j.yaweett
J.lt.foulk c.r.oibbs D.R.Amy P.ft.2akriski Research Library Caleert City
C .L.Voods-D.B.Schrock Cleveland
V.F.Bixby
ft.E.Brodine *B. H .Harrington ft.H. Larson-C .0 Segner (7) *p.H .Lawrence 0-H.Metzger
R.D.Scott-J.L.Helson
B.N.O'Zwlcker
L.Weurth
Henry C.B.Cooper-J.P.Piers
Long Beach *V.D.Robb-A.W.Clements
LoualvlUe
*L.0.Crunkleton-S.S.ftlchel3 Niagara Palls
*rTR.Llnak
Psdrlcktown
J.A.Klupar Development Center
#L.F.Arnold *1*. A. Bennett R.R.Bloor
L.A.Chandler B.A.Collins L.B.Crider
L.I. Conklin B.G.OeCaplta
B.A.DlUddo J.L.Dorset* F.myterfco
Fleming C.H.Cotheleer R.H.greager C.H.Lufter R.J.Meyer J.A.Nlkora
C.X.parks J.M.Ryan
H.H.Sherwood J.A.TePas "O.L.Mheelock
R.J.ftolf i
R.A,Yount
Technical Cm 1 c.T.y. (3)
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MAJOR OBJECTIVES
1
The major objectives of this research problem are:
1) To develop the required analytical Instrumentation and techniques for pyrolyalng PVC resin, compounds, copolymers, and other polymers, and
2) To expand this technology into areas Involving thermo-oxidation and combustion.
LIMITED OBJECTIVES
The objectives of this study vert to study the combustion products free vinyl chloride monomer in Joint work with personnel from Dow chemical. Uniroyal and Borden Chemical* This task force is a part of the overall committee sponsored by the Manufacturing Chemists Association to Investigate the burning of vinyl chloride monomer*
SUMUJtY OP CONCLUSIONS
A) Conflicting evidence exists on phosgene as a combustion product. Borden,
Uniroyal and BPG have reported none present; Dow Chemical has repo ted the following levels of phosgene for the following conditions:
diffusion flame rmalimf-.ftimi
VCM bmfflthg In an opendlah VO burning In a rupturedtank
ppa (In air) nil 10-200
15*20 40
(All gas samples were obtained directly above the flame In each case)
B) The following conclusions were derived from studies carried out at BFG:
1) When vinyl chloride in burned, 52% of the monomer unit is converted to HC1. This accounts for S9Jf of the available HC1; the remaining lid was assumed lost on the combustion apparatus and adsorbed on the generated soot particles. In addition, a small portion of the VCM escaped combustion.
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2) A typical vinyl chloride flame releases 3-5$ unoxldlzed carbon In the fora of a light soot.
3) The ratio (welgftt/velght) or carbon dioxide to carbon nonoxide lr. vinyl chloride combustion gases was found to be 5*31.
4) ihe overall combustion profile for vinyl chloride Is:
Combustion Products
Welrtt %
flCl (determined) HCl (assumed lost) Carbon (as soot) Carbon (as CO;) Carbon (as CO)
52 6 4
30 3
5) The relative concentration of HCl, CO, C02 and phosgene mews aa-.aj m a sample of air obtained directly above a vinyl chloride flame was:
Component
SSl Concentration
MAC
HCl CO
C02 Phosgene*
27,000 10,000
58,000 40
5 50 --
0.5
6) Based on the Maximum Allowable Concentrations (MAC, above) of these combustion products, the overall toxicity from burning vinyl chloride is due to the gross amount of BCl In the combustion geses. the concentration of phosgene Is 80X the MAC value, carbon monoxide Is 200X and HCl Is greater than 5000X
the MAC value.
On the other hmad, the toxicity aay be due to the carbon monoxide content.
This hms been JBc*se with the combustion gases from PVC which also contain e hl^rofitgtl of BCl.
^ testing^Smld be required to differentiate the two situations.
2037500 ;
* Value obtained by Dow for a ruptured tank fire.
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1
INTRODUCTION
3
In a previous report*, the question of the presence of phosgene in the
combustion gases from vinyl chloride monomer (VCR) was dealt with. At that time, it was reported that no phosgene (down to 10 ppm) could be detected when vinyl
chloride was burned under diffusion flame conditions (no premixing of VCR and air). other laboratories have also investigated the "phosgene question" and have
reported the following results:
Borden Chemical - phosgene not detected
Ohlroyal
- phosgene not detected
Dot Chemical - not datected for VCR diffusion flame, 10-40 ppm
detected for YCH burning In an open dish or In a
ruptured tank (sampled lnelistely above the
flame); 40-200 ppm detected for a premixed vat
tUm
As a result of the Dow report, a number of additional experiments w*re carriei out in an attempt to duplicate their work. The same combustion apparatus was used as previously descrlbedl except for the following modification. R. Daniels of Dew In a personal communication has raportad that HC1 (but not phosgene) is removed from combustion gases when the gases are directed through mossy zinc. The VCR combustion gases ware treated in this manner and again analyzed for phosgene. Unfortunately, no phosgene could be detected.
Prom a toxicological standpoint, the amount of phosgene found by Dow is insignificant In view of the gross amount of BC1 that Is present.
BC1 Determination
the combustion spy rams has been previously described1 in detail. Briefly,
It consists of m totsj^^fltbustloa burner containing VCR and air lines, a chimney
with an outlet at
am all glass trap for analyzing HC1 or phosgene and
an outiat line commeell^le a vacuum ptap. yell vent holes were drilled into
the base of the burner housing so that air could ba drawn through the entire system.
For typical BC1 determination, the apparatus was well seasoned with combustion
products before any analyses were carried out. 71m decomposition gases were bubbed through 3 gas dispersion tubes (in parallel) Into s standard sodium hydroxide solution. The off gases from this scrubber were directed Into e silver nitrate solution In order to Insure that a complete titration had taken place. A back titration cf the sodium hydroxide solution with s standard BC1 solution completed the analysis. The amount of HC1 In the combustion gases was then related to the amount of VCR burned. As a result of this snslysls. It wes found that $2% of monomer by weight is converted
to HC1.
1 R.M.O'Rare, Part VIII, Status Report, 12/4/1969.
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Ash content
Burning vinyl chloride has a characteristic cool, carbonaceous flame. it was of interest to determine the amount of carbon in terms of the amount of vinyl chloride consumed. Experiments were carried out In which the off gases from tne vinyl chloride flame were directed through a piece of glass wool. This effectively trapped all of the unturned carbon from the flame.
The following table summarizes the results of two typical runs for two different burning rates. The results indicate that at a higher feed rate of vinyl chloride Into the burner with a constant air supply, the amounts of carbon In the flame increase.
Total VCM Burned Rate of VCM Consumption
Amount Carbon Dapoalted * Onbumt carbon
U.OOg 0.133 g/mln. 0.226 g
5.5*
9.90g .089 g/mln.
02..283*5 g
Ratio of CO2/CO
This important value was obtained by a gas chromatographic analysis of the
off-gases from the VCM flame. A combination of columns (porapak S, 6* x 1/4" and
5A Molecular Sieve* l1 x l/V) enabled the collate separation of nitrogen, oxygen,
CO?* CO* VCM* and ethylene. The off-gases from the flame were sampled at two points
in the combustion apparatus. One sample was taken at the top of the combustion
chimney with no air flow through the system; the other was taken directly above the
flmme. Q.C. analyses of these samples showed that the weight ratio of CO2/CO was
16.5 for the first sample and 5.8 for the second. It was f*lt that the I0.5 ratio
was too Mg*
was mot representative of the actual fire conditions. The conditions
under which this sample (16*5 ratio) were taken were such that the combustion prodmcts
wmre released to rraifined area (no air stream to removo products from combustion
chUney). Tbs rtmaltgfr (Sis was a secondary reaction involving the combustion of
carbon ioooxldc. .BaflMmoidiiarlly high ratio of COg/CO.
Tbs cooeontrmtlflRf CO* CO?, R, and 02 are presented In the following table* along with the appropriate response factors.
ffiMMimnfc
Rssmonse factor
*-
Oxygon Carbon dioxide Rltrogen
Carbon monoxide
1.164 0.906 1.000
0.377
14.7 5.8
78.5 1.0
An oxygen balance could not be calculated due to the loss of combustion water in the sampling apparatus.
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Unfortunately the HCl content of this air sample could not be calculated due to the poor resolution of this component on the gas chromatograph. This analysis nevertheless clearly defines the. toxicity of the combustion gases fros VCM. Assuming that Dow's phosgene data Is correct, the concentration of this
In the lamellate vicinity of the flame* Is 40 ppm or 80 times the accepted Maximum Allowable Concentration; the concentration of carbon monoxide near the
flame Is 10,000 ppm or 200 times the MAC value. Based on the amount of CO and
CO? in the air sample, the concentration of HCl Is estimated to be 27*000 ppm or 5400 times the MAC value.
Toxicity of Combustion Products
The toxicity of the combustion products from vinyl chloride might be expected to be due to the high content of HCl. However, an Important piece of work should be interjected at this point. H.fl.Comlsh? has shown that the toxicity of the combustion products from poly (vinyl chloride) which also contain a high level of HCl art due not to this gas but rather due to carbon monoxide. This work showed s definite relationship between animal mortality (mice, rats, guinea pigs, rabbits and monkeys) and the concentration of blood carboxyhenoglobln.
A similar situation may be In effect for the combustion products from vinyl
chloride although the
Allowable Concentration Values Indicate that HCl is
the greatest contributor to the overall toxicity.
Additional Studies
The analytical results from this study have been extended to actual fire conditions Involving VCM. L.B.Crlder has initiated a computer study In which the concentration of HCl and carbon monoxide are described in tenis of:
1) distance from the fire 2) type of geographic terrain idiere fire occurs 3) wind conditions^ end 4) temperature o^HTtlons
This results of Jfvtadj will be aade available to MCA as a guide fer
dealing with future VC* flree.
Ruptured vessel fire 2 H.H. Cornish, Arch. Enrlrom. Health, Vol. 19, July 19*9, p. 15-21.
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