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NATIONAL BUREAU OF STANDARDS REPORT

8546

EUROPEAN TRIP

August 15 to 29 1964

by

E. C. Cireitz

U. S. DEPARTMENT OF COMMERCE

NATIONAL 00REA0 OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards is a principal focal point in the Federal Government for assuring

maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. Its responsibilities include development and maintenance of the national stand- ards of measurement, and the provisions of means for making measurements consistent with those standards; determination of physical constants and properties of materials; development of methods

for testing materials, mechanisms, and structures, and making such tests as may be necessary, particularly for government agencies; cooperation in the establishment of standard practices for incorporation in codes and specifications; advisory service to government agencies on scientific and technical problems; invention and development of devices to serve special needs of the Government; assistance

to industry, business, and consumers in the development and acceptance of commercial standards and

simplified trade practice recommendations; administration of programs in cooperation with United

States business groups and standards organizations for the development of international standards of

practice; and maintenance of a clearinghouse for the collection and dissemination of scientific, technical, and engineering information. The scope of the Bureau’s activities is suggested in the following

listing of its four Institutes and their organizational units. Institute for Basic Standards. Electricity. Metrology. Heat. Radiation Physics. Mechanics. Applied Mathematics. Atomic Physics. Physical Chemistry. Laboratory Astrophysics.* Radio Standards Laboratory: Radio Standards Physics; Radio Standards Engineering.** Office of Standard Ref- erence Data. Institute for Materials Research. Analytical Chemistry. Polymers. Metallurgy. Inorganic Materials. Reactor Radiations. Cryogenics.** Office of Standard Reference Materials. Central Radio Propagation Laboratory.** Ionosphere Research and Propagation. Troposphere

and Space Telecommunications. Radio Systems. Upper Atmosphere and Space Physics.

Institute for Applied Technology. Textiles and Apparel Technology Center. Building Research.

Industrial Equipment. Information Technology. Performance Test Development. Instrumentation.

Transport Systems. Office of Technical Services. Office of Weights and Measures. Office of Engineering Standards. Office of Industrial Services.

* NBS Group, Joint Institute for Laboratory Astrophysics at the University of Colorado. ** Located at Boulder, Colorado.
NATIONAL BUREAU OF STANDARDS REPORT

ms PROJECT

1002-11-4210121

NATIONAL BUREAU OF ST

/

for use within the Government, j and review. For this reason, the whole or in part, is not authori, Bureau of Standards, Washingto

the Report has been specifically |

September 8, 1964

EUROPEAN TRIP

August 15 to 29, 1964

by

E» G. Creitz

IMPORTANT NOTICE

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015.

NBS REPORT

8546

s accounting documents intended objected to additional evaluation

listing of this Report, either in Office of the Director, National

the Government agency for which

pies for its own use.

«. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

EUROPEAN TRIP

August 15 to 29, 1964

E, G, Creitz

ABSTRACT

The purpose of the trip was to attend the 10th

International Symposium on Combustion at Cambridge,

Engl and, and to visit two laboratories in Germany

where work is being done that is of interest to us.

The strongest overall impression of the Symposium

was left from listening to theoretical papers on the

mechanisms of combustion. It appears that the com- bustion of I s not at all,we 11 understood. Since

this is probably the simplest flame system, it leaves

the understanding of more complicated systems (and

ionic reactions in such systems) diseouragingly in

the future.

Conversations with Drs. Fish and Rumberg on the

subject of analysis of combustion products was similarly discouraging except for determination of stable

compounds, present in relatively high concentration

and in the absence of smoke or soot. The compounds

of greatest interest are, of course, those occuring

in small concentrations in fires where smoke is present.

The recovery of gaseous compounds adsorbed on carbon

particles, particularly if the compounds are reactive,

presents problems for which no solution is yet known.

It appears that no one has attempted the analysis of

smokes which consist largely of tar aerosols, where

the problems are just as complicated.

European Trip

August 15 to 29, 1964

E. C* Creitz

I. The Symposium on Combustion

A . Business anc| Social Aspect

g

Registration at the 10th Symposium was the largest of any to date - some 800 registrants including about 150 wives, represented eighteen

countries and required a symposium budget of some L 12,500. The

retiring treasurer reported a total membership of about 2700 in the

combustion Institute. The Institute operates on a biannual budget of

about $100,000.

The new board of directors, elected at the business meeting consist

of j

W. G. Agnew

W. J. Bennet

L* Bragg

Friedman

N. A. Hall

H. G. Hot tel

¥. M. Rohrer

E* S« Starkman

General Motors Company

Marquardt Corporation

Rolls Royce Ltd.

Atlantic Research Corporation

Commercial Engineering Education

Massachusetts Institute of Technology

University of Pittsburgh

University of California, Los Angeles

R. S. Levine North American Aviation

The volume of papers from the 10th Symposium is to be dedicated to

Dr. Bernard Lewis. The Sir Alfred Egerton gold medal was presented to

Professor Paul Lafittee by Lady Egerton. Professor A. R. Ubbelode

presented the Bernard Lewis gold medal to Professor R. G. W. Norrish.

The silver medal for the best paper presented at the 9t.h Symposium was presented to N. M. Howe, C. W. Shipman, and A. Vranos by Professor

Glaa C. Williams, who characterized one of the students as one of his

'’grand students. 11

The 11th Symposium is to be held in 1966 at the University of

California at Berkeley.

2

Extra-curricular Symposium activities included a ladies" program,

a garden party, a formal reception, a trip to Woburn Abbey, where the

official dinner was held and an organ recital in King's College Chapel.

B . The Technical Program

The 133 technical papers were presented in three concurrent sessions.

They were divided, as to technical content as follows:

Flame Chemistry - 13 papers

Detonation - 6 papers on condensed phase and

6 papers on "mostly gas phase."

Biscussiten on Electrical Properties of Flames - 12 papers.

Discussion on Elementary Combustion Reactions - 24 papers.

Discussion on Aerodynamics in Combustion

1. Free Burning Fires - 8 papers

2. Rocket Instability - 4 papers

3. LOw-speed combustion - 5 papers

4. High-speed combustion - 5 papers

Reaction Kinetics - 12 papers

Combustion and Flow - 12 papers

Fire Research - 6 papers

Solid Propellant Combustion Fundamentals - 6 papers

Flame Spectroscopy - 7 papers

General - 7 papers

The first session attended was that on Electrical Properties of

Flames. A paper on Ion Sampling from Chemical Plasmas, by G. N. Spokes

and B. E, Evans was of interest because it covered the effects of

charge accumulation at the inlet orifice (of a dielectric material) of

a mass spectrometer. A pulse of ions was generated in a plasma by

electrical discharge and the time delay for appearance of ions in the

spectrometer was observed. Gas velocities in the order of 2000 to

5000 cm/ sec were used through the orifice. Delays as long as 100

seconds were observed. They attribute these delays to the plating-out

of ions on the orifice. They observe that 8 to 9 volts will prevent

all positive ions from entering an 0.05-inch orifice. Knewstub observed

- 3 -

the£ they had found that 10 volts is sufficient to "de-cluster"

H^Q ions since they observe mass 73 going to mass 55 and then to mass 37. Miller, Aerochem, also observed "de-clustering" of

negative ions from flames and additionally observed that most of

the negative charge carriers were ions, rather than electrons.

Spokes* and Evans succeeded in removing some of the delay by making

the orifice of a thin dielectric with conductor on each side and

the establishment of an electric field between the conductors®

G. Wortburg showed that the maximum ion concentration occurs

at the point of maximum heat release in a flat flame at atmospheric

pressure* This seems to relate ion production with chemical recombination rather than with dissociation.

A paper on Langmuir probes confirmed our contention that double

probes can measure only positive ion concentrations. Proper conditions for the use of single probes are outlined and their accuracy

demonstrated. One comment was that collision cross sections for

inelastic collisions are somewhat larger than for eleastic collisions.

W. W. Balwenz reported that carbon particles in a flame had no effect on electron concentration, that the diameter of a flame, as measured by electrons, is larger than its optical diameter and that

when alumina is added to a supersonic flame the shape of the shock

front alters and when it does, the electron distribution follows the

gas and not the alumina particles.

Two papers on the acquisition of charges by solid particles in a plasma indicate that the particles may be charged either positively

or negatively depending on conditions. In fact, such particles

behave as floating probes and aerodynamic effects may be very significant in the removal of the double-layer.

A paper with the very impressive title "On the Effect of Kinetics

of Elementary Reactions on Ionization in Stationary and Nonstationary

Supersonic Expansion and Compression of Gases" by Miss N* I.

Yushchenkova and S. I. Rasterin, is directly applicable to all mass

spectroscopic sampling of ions from flames. One may expect that for

each gas -dynamic flow there is a limit on the amount of ionization

that can exist. It thus appears that ions may disappear simply because

of the rate of expansion thru an orifice. The paper applies, of course,

only to mass spectrometers where ionization precedes expansion through

the orifice.

In the Discussion on Elementary Combustion Reactions, the first

paper dealt with gas phase oxidation, at 30 o C, of neopentane and other

- 4 -

hydrocarbons. Unexpectedly, the reaction products are formed by

direct displacement of two groups (H atoms usually) of the parent

hydrocarbon, with the attendant formation of a carbonyl bohd,

rather than by a free radical mechanism involving extraction of a single group or H atom at a time. While not of direct interest to

those working at high temperatures, this information sheds some light on low temperature oxidative processes in organic materials

in general.

Many papers in this session, regardless of the system being j

studied, seemed to depend, in final analysis, on the chemistry of the

hydrogem-oxygen system. Most of the studies were made in flow systems

which are affected by pressure, composition and temperature gradients,

by purity of the reactants and by surface catalysts* A curious fact,

in connection with the study of the H^-C^ s Y stem is that, at flame

temperature, pure hydrogen does not dissociate.

In one study it was shown that OH radicals react 2.1 times as fast with CH^ as with CO and about 70 times as fast with formaldehyde,

all work being done in the neighborhood of 500°C. At higher temperatmres, the ratio of reaction rates increases, which indicates that

the oxidation of CO is the slowest of these processes. Fristrom,

et al, show that H and 0 atoms do not react directly with or

C f> H / while OH radicals do. On the other hand, Kaufman gives a very

high rate for the destruction of OH radicals by 0 atoms-r something

like ,1 per less than 10 collisions. Tennimore and Jones showed that

the rate . of heat -ce-volution in the Ht,-^ reaction probably depends on

the irate of formation of HC^ radicals.

It was reported that the formation of polyacetylenes play a decisive role in the formation of carbon particles. It was argued that

carbon^Q^y has more hydrogen present than polyacetylenes, so that

they cannot

^

precursors of carbon.

A study of dissociation and recombination of 0

^ showed that, after

receiving its dissociation energy, an oxygen molecule exists for a period of time, of the order of a vibrational relaxation time, before

dissociating and, if electrons are liberated, it is subsequent to the

dissociation. A lot of discussion on ionization processes and the

effect of additatives followed this paper. A paper from Aerochem

Laboratories on chemiluminescence followed and brought out the fact

that electrical discharge through gases produce effects on combustion

which are long lasting. This paper showed the existence of both ions

and free radicals. The ion CHO* was the dominant ion.

~ 5 -

Electron attachment in 0

2 was observed to be decreased by the

addition of CO^ at 400-600°K, bat equilibrium constant values indicate that, at 1000°K, it has little effect at concentrations up to

about 1/4 atmosphere, (Phelps & Pack-Westinghouse) , Biondi, et al,

show that dissociative recombination is the most efficient attachment

process for electrons and molecular ions and is responsible for the

large recombination rates in afterglows. They found that (a)

molecular positive ions must be present to observe large recombination rates, (b) when diatomic ions are present, excited atoms are formed in the recombination process and (c) these excited atoms

have kinetic energy of dissociation substantially in excess of

thermal energy. Glass (Harvard and Miller )(Aerochem) have observed

the ion * Miller proposes that it is formed according to

GH* +

^

C^H* + 0 . Miller believes the primary negative ion

to be C^".

Van Tiggelen’s group report seeing a large number of negative ions

from flames, ranging in mass from 16 (Q~) up to mass 63, When QL

2 is

added cl" ions replace all other negative ions. Both C0 9 " and

GW" were reported, but Dr, Sugden doubts the probability of their

being present because of their high electron affinities. Dr. Knewstub

commented that the speed of ions through the inlet orifice must be

at least 2,5 cm/ sec in order to get the ions through the orifice and

that a high sampling rate and resultant cooling favors dissociative

attachment of the electrons.

G, Per senna lia

In talking with A. V. Phelps of the Physics Department, Westinghouse

Electric Corporation, it was learned that Dr. R. E. Fox, who was responsible for the excellent work on electron attachment by SF^ has

become an administrator and is out of laboratory work. Phelps seems

to think that probably in flames, as well as in gas discharges, the

most important process for the disappearance of electrons is, by far,

that, of dissociative attachment. In discharges, attachment occurs to

positive ions. W. J. Miller, Aero Ghem finds dissociative attachment

in flames. He thinks that the process usually is

e + c

2h2 o* —> e

2

"{ + h

2 o.

He also finds 0" and OH" somewhat downstream from the flame front.

Most negative ion, concentrations fall off rapidly as the pressure

increases, OH" being the most persistent.
1
~ 6

Dr. A. Fish, Imperial College said that they had not been able to

determine Br orfflBr with the gas chromatograph and had had to go* to wet

chemical methods* They had not been much interested in bromine compounds,

since bromine is not much used in plastics* It was implied that the gas

chromatograph was a useful tool but not the complete answer to the analysis

of gaseous combustion products.

Dr* T, M. Sugden has left Cambridge University and now works for

Shell Oil. From the way he talks, one assumes that he is not working in

ionic phenomena at the present.

Dr. J. Lawton, Imperial College, has been working on the effects of

electrical fields on flames, in an attempt to improve efficiencies and

augment enthalpies by increasing ionization in flames. Power fluxes can

be improved, but only at considerable expense for equipment and electrical

power.

II. The German Laboratories

A, The State Material Testing Center at Dortmund-Aplerbeck .

This laboratory was established by the State - Westphalia) as an unbiased testing laboratory to make tests for any requester, of all kinds

of materials. In general, they do not test structures. The center receives

about 25% of its income from the State, the rest coming from charges made

for the tests done. The amount of fire testing is rather limited, and seems

to be designed to produce results for use in compliance with building cfodee.

The apparatus for flame spread is similar to that of the British, con- sisting of a square burner, fed at a specific gas rate, around which is a tall, box-like array of the specimen material. The vertical distance of

flame travel, and the temperature rise are used in computing a flame spread

index.

They are in the process of constructing an enclosure for determining

the effects of floor loading of industrial materials, which may have un- usual fire properties and may be stored under conditions of unusually high

loadings. The enclosure is of sheet iron, on a concrete base, about

15 x 15 x 15 feet, and can be ventilated by air supplied through four large

ducts. It was stressed, both here and in Karlsruhe, that there is very

little Governmental control over fire hazards in industrial installations.

This laboratory is also doing work in the analysis of combustion

products from burning plastics. Their furnace is a conventional zone-refining

furnace, in which the sample is placed in a horizontal combustion tube and a small ring-shaped furnace is motor-driven to traverse the combustion tube at

a selected constant rate. Air is supplied at one end of the combustion tube

and analytical samples are removed from the other end. Smoke from the exit

end of the combustion tube is also led to a photoelectric device for measurement of smoke density.

7

In Dr. Humberg's opinion, the literature survey of gas analytical

methods and results, done by the Underwriters' Laboratories for the

Manufacturing Chemists Association, left much to be desired and he has

prepared a bibliography augmenting it, a copy of which he gave us.

Dr. Rumberg's analytical methods consist almost entirely of gas

chromatographic and wet chemical methods. Some spectroscopic apparatus

is available for occasional use, but no mass spectrometer is available.

He is very conscious of the difficulty of doing accurate analyses of

components which may disolve in liquid aerosols or adsorb on solid particles

in smokes, particularly when such solution or adsorption may lead to re- action of some components with others. In his opinion, one must search for

each component of the mixture by a separate analytical method before groupanalytical methods such as gas chromatography can be trusted. He is probably right, but the prospects for complete analysis of a smoke are discouragipgfy far in the future.

In connection with smoke density measurements, Dr. Rumberg pointed out

that the photocel used should have a spectral response similar to the human

eye, or the correlation between visibility and smoke density is meaningless.

Information was obtained from Dr. Rujrtberg on other laboratories in

Germany which are working in fire-related fields.

1. Bundesanstalt fur Materialsprufung

Berlin-Dahlem

Unter den Eichen 87

Attn: Dr. Seekamp

This institute does work in construction and materials, ignition

and chemistry and Dr. Seekamp should be contacted for the names of others

in related fields.

2. Amtliche Forschungs-und Materialprufungranstalt fur das Baumesen

Otto-Graf Institute

7 Stutgart-Volhingen

Robert-Leicht Str. 209

Attn: Prof. Egner.

Specializes in wood and wood construction

3. Schlessig-Holsteinische

Lande sb randka s se Kiel, Germany

Attnj Dr. Jach

8

4. Baustaf fprufamt , Hamburg

Attn: Dipl-Ing. Hertell

5. Deutches Kunstaff Institute

Darmstadt

Attn: Dr. Braun

Pyrolysis of wood and plastics.

6. Institute fur Holzforchung ind

Holztechnik der Univ. Munchen

Behavior of wood.

7. Also in Berlin, working in inorganic materials:

Group 4 Technische Gase

Feuergefahrliche und Explossive Stoffe

Attn: Prof. Roenen

B. The Research Center for Fire Protection Technique , at the Technical

High School, Karlsruhe.

This -©enter was started by Dr. G. Magnus in the hopes that it might

become a Federal fire research laboratory. Since we were there three years

ago, hard times have befallen it. Dr. Magnus, who appears to be the only

person available with the right proportions of personality and connections

has become too busy, with the Manheim Fire Brigade, and his own industrial

activity to manage, as well as a technical committee of the V.F.D.B., so that he has not been able to give the Center the requisite amount of time.

Competition from State-supported and university laboratories has increased,

so that the idea of a Federal center has apparently been dropped. There

have been losses of top quality personnel, and the amount of work has

decreased , (it is now all contract work for industrial sponsors). Present

plans appear to be to make the laboratory a University- (Technische

Hochschule) sponsored laboratory, with a professor as its head. No

suitable guiding hand has been found and the Hochschule is reluctantly

about to confer the title of Professor on Dr. Magnus. Mr. 'Rinrichs has

done all his graduate work but has not been able to get a ti,me assigned

for his final examination. His thesis appears to be the only unclassified

work done recently.

USCOMM-NBS-DC