6712SR Refrigerated Sampler
Appendix C General Safety Procedures

C-6

“Be very careful to avoid high H2S concentrations, flammable

atmospheres, and hazards of physical injuries. Remember that

much H2S may be released by the stirring up of sludge in the

bottom of a structure. Obey your senses in respect to irritating

gases, such as chlorine (unconsciousness comes suddenly from

breathing too much). Be cautious about strange odors. Do not

determine percent oxygen in the air. There is a danger that the

result will influence a man's thinking about the seriousness of

the real hazards. Most important, use ample ventilation, and do

not enter a potentially hazardous structure except in a good

safety harness with two men at the top who can lift you out.”

Table C-1 Hazardous Gases
Gas Chemical
Formula
Common
Properties
Specific
Gravity or
Vapor
Density
Air = 1
Physiological
Effect*
Max
Safe
60 Min.
Exposure
ppm
Max.
Safe
8 Hour
Exposure
ppm
Explosive
Range
(% by vol.
in air.)
Limits
lower/upper
Likely
Location
of
Highest
Concentration
Most
Common
Sources
Simplest and
Cheapest
Safe Method
of Testing
Ammonia NH3Irritant and poison-
ous. Colorless with
characteristic odor.
0.60 Causes throat and
eye irritation at
0.05%, coughing
at 0.17%. Short
exposure at 0.5%
to 1% fatal.
300
to
500
85 16 25 Near top.
Concentrates
in closed up-
per spaces
Sewers, chemi-
cal
feed rooms.
Detectable
odor at low
concentrations
Benzene C6H6Irritant, colorless
anesthetic
2.77 Slight symptoms
after several hours
exposure at 0.16% to
0.32%. 2% rapidly fatal.
3,000
to
5,000
25 1.3 7.1 At bottom. Industrial
wastes,
varnish, sol-
vents.
Combustible
gas indicator
Carbon
Bisulfide
CS2Nearly odorless
when pure, color-
less, anesthetic.
Poisonous.
2.64 Very poisonous,
irritating, vomiting,
convulsions, psychic
disturbance.
— 15 1.3 44.0 At bottom An insecticide Combustible
gas indicator
Carbon
Dioxide
CO2Asphyxiant, Colorless,
odorless. When
breathed in large
quantities, may cause
acid taste. Non-flam-
mable. Not generally
present in dangerous
amounts unless an
oxygen deficiency
exists.
1.53 Cannot be endured at
10% more than a few
minutes, even if sub-
ject is at rest and oxy-
gen content is normal.
Acts on respiratory
nerves.
40,000
to
60,000
5,000 — — At bottom;
when heated
may stratify
at points
above bottom.
Products of
combustion,
sewer gas,
sludge. Also
issues from car-
bonaceous
strata.
Oxygen
deficiency
indicator
Carbon
Monoxide
CO Chemical asphyxiant.
Colorless, odorless,
tasteless.
Flammable.
Poisonous.
0.97 Combines with hemo-
globin of blood.
Unconsciousness in 30
min. at 0.2% to 0.25%.
Fatal in 4 hours at
0.1%. Headache in few
hours at 0.02%.
400 50 12.5 74.0 Near top, espe-
cially if present
with illuminat-
ing gas.
Manufactured
gas, flue gas,
products of
combustion,
motor exhausts.
Fires of almost
any kind.
CO ampoules.
Carbon
Tetra- Chl
oride
CCl4Heavy, ethereal odor. 5.3 Intestinal upset, loss of
consciousness, possi-
ble renal damage, res-
piratory failure.
1,000
to
1,500
100 — — At bottom. Industrial
wastes,
solvent, cleaning
Detectable odor
at low concen-
trations.
Chlorine Cl2Irritant. Yellow-green
color. Choking odor
detectable in very low
concentrations.
Non-flammable.
2.49 Irritates respiratory
tract. Kills most ani-
mals in a very short
time at 0.1%.
4 1 — — At bottom. Chlorine cylin-
der and feed line
leaks.
Detectable odor
at low concen-
trations.