Armored Force 
Medical Research Laboratory 
Fort Knox, Kentucky 
Report On 
GUN FEME HAZARD FROM 37 MM GUN IN ¥$ LIGHT TANK 
Project 3-2 
February 18, 19l*3 ARLDIDD FORCE LLDIGAL RR3EARCH LABORATORY 
Fort Knox, Kentucky 
Project No, 3-2 
File No. 724.41 
February 16, 1943 
Kir CuT ON LfUi I HAZARD 
FROL 
. 37Ln GUN IN U5- LIGHT TANK 
1. PROJECT: Determination of the Characteristics and Effects Upon 
the Crew of Gun Fumes from Firing of the weapons in Tanks of the M-5 
Series, 
a. Authority - Letter Commanding General, Headquarters Armored 
Force, Fort Knox, Kentucky, 400.112/6 GKOHD, dated September 24, 1942. 
b. Furpo.se - To determine the extent of the hazard from fumes 
released in firing the 37 run in the Ii-5 light tank. 
2. DI5Cui33IGi.: 
a. Methods - 
(1) Fire Fattern:. Five bursts of 1C rounds; five seconds 
between rounds and 5 minutes betveen bursts, 
(2) Tank operation: Tank buttoned-up and engine operated at 
its normal idling speed. Full creiv in tank. Wind from tlie rear, 
(3) •Arlaunition; 3?dhi AF 1,151 FKK M2 
3. CONCLUSIONS: 
a. Under the conditions of tost, carbon monoxide concentrations 
exceeded sliyhtly the maximum acceptable level of 0,05/« 
b. There ivas no accumulation of corbon monoxide from one burst 
to another, 
c. Concentrations of ammonia vcre not hiyh enough to -cause eye 
irritation. d, Concentrations of oxides of nitrogen were well within the 
acceptable limit, 
e_. Increased blood concentrations of carbon monoxide did not 
exceed 7*4 percent in any crew member during a 25 minute period of ex- 
posure, 
f. Control of 3?hm gun fumes in the LI-5 light tank is acceptable. 
4. Pi^OUENDATIONS: 
a. So long as the basic ventilation in the Id-5 light tank is 
not changed, further consideration of the gun fume problem is unnecessary, 
b. This tank should not be fired with the tank engine dead un- 
less the turret hatch is opened. 
Submitted By: 
liajor Hatch 
Captain Nelson 
Lieutenant Bichna 
lieutenant Walpole 
Lieutenant Horvath 
ai r RCViSD 
kACHLE 
Lieut. Col., Kedical Corps 
C OKirnanding 
2 Incls. 
#1-Appendix I, Sampling and Analysis 
#2-Appendix II, with Tables I and II and 
Figure I. API END IX I 
SA11LING ai:d analysis 
1. Carbon monoxide. 
a. Collection of air samples: Three methods were employed. 
(1) The Line Safety Appliances continuous indicator, 
(2) Instantaneous samples in evacuated flasks for the 
determination of peak concentrations and clearance rates at the end of 
firing, 
(3) Continuous samples in evacuated flasks, sampling being 
continued at a constant rate throughout a given test in order to determine 
the average concentration for a given condition. Samples were collected 
in this manner at one or mors crew positions* 
b. Blood samples for the determination of carbon monoxide content 
were obtained from the tank crew members in the standard, manner before and 
at the end of all complete tests. They were not obtained in exploratory 
tests. 
c. GO Analysis: Evacuated flask samples were analyzed by the 
iodine pentoxide method and blood samples by the Scholander-Roughten and 
Spectro Fhotometric methods. The LSA GO indicator vjas checked at regular 
intervals against known air-CO mixtures. 
2. Concentrations cf ammonia end oxides of nitrogen were determined 
in portions of the instantaneous flask samples, employing the Kessler and 
phenoldisulphonic acid procedures respectively. 
1 APPENDIX II 
Concentration of carbon monoxide generated in the M-5 light tank 
during the firing of the 371m gun, with the fire pattern described in 
the body of this report, are given in Table I and are shown graphically 
in Figure I. Increase in blood concentrations of CO after 25 minutes 
exposure are presented in Table II. Concentrations of ammonia and ox- 
ides of nitrogen did not exceed 40 and .10 ppm. respectively. 
TABLE I 
GONG. OF CARBON I'OKOXIDE 
F HOI l 
371 jn GUN IN N-5 LIGHT TANK 
After 1st Burst - (9 rds), Loader 0.09 
After 2nd Burst - (10 rds), Loader 0.173 
After 3rd Burst - (10 rds), Loader 0.250 
After 4th Burst - (10 res), Loader 0.206 
After 5th Burst - (6 fds), Loader 0.063 
Cont, Sample - Loader 0,063 
Cont, Sample - Gunner 0.053 
Clearance Rate after last burst 20 Sec. 
(Time for Cone, to decrease 50%) • TAB'LL II 
CARBON MONOXIDE CONCENTRATIONS IN BLOOD OF CREV; IS&iHSRS 
(25 LINUTES EXPOSURE) 
1 
i 
o 
o 
*>9 
i 1 
j 
CO 
Hemoglobin 
in Air 
: Cl GW FEliBER 
as 
e/ 
(O 
of Total Figment 
From 
! 
Before 
After 
Continuous 
i 
1 
Exposure 
Exposure 
Increase 
Samples 
! 
1 
! _oader 
4*2 
11.6 
7.4 
0.063 
Gunner 
7.4 
11.0 
3.6 
0.053 
Driver 
1.8 
2,6 
0.0 
Asst. Driver 
6.0 
6.9 
0.9 
i 
i ■ .! 
.OADER 
Gunher 
TIME - MINUTES 
Carbon Monoxide Concentrations 37 M.M. Gun * M'5 Light T>snk 
k RDS' 
lO'RDS 
n& i 
10-RDS 
10RD3 
s Legend 
Peak Cong. 
Die away Conc. 
' AVE Conc. 
Conc By m.5,a. 
Rds, Fired 
$>Rt>S 
Carbon Monoxide -Percent