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Isco 4700 Refrigerated Sampler
Appendix B General Safety Procedures
Gas
Chemical
Common
Formula
Properties
Ammonia
NH
Irritant and poisonous. Col-
3
orless with characteristic
odor.
Benzene
C
H
Irritant, colorless
6
6
anesthetic
Carbon
CS
Nearly odorless
2
Bisulfide
when pure, color-
less, anesthetic.
Poisonous.
B-6
tions. A supposed safety device that is unreliable is worse
than none at all.
"Remember that the nose fails, too, when it comes to sens-
ing dangerous concentrations of H
"Various other toxic gases have been mentioned in some
publications. It is unlikely that any person has been
asphyxiated in a sewer by any of those other gases, except
possibly chlorine. The vapor of gasoline and other hydro-
carbons is sometimes present in amounts that could cause
discomfort and illness, but under that condition, the explo-
sion hazard would be far more serious. The explosimeter
tests, as well as the sense of smell, would warn of the dan-
ger. Pipelines in chemical plants might contain any num-
ber of harmful vapors. They, too, are sensed by smell and
explosimeter tests if they get into the public sewer. Such
occurrences are rare.
"The attempt to instill a sense of urgency about real haz-
ards is diluted if a man is told to give attention to a long
list of things that in fact are irrelevant.
"Be very careful to avoid high H
ble atmospheres, and hazards of physical injuries. Remem-
ber that much H
sludge in the bottom of a structure. Obey your senses in
respect to irritating gases, such as chlorine (unconscious-
ness comes suddenly from breathing too much). Be cau-
tious 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 B-1 Hazardous Gases
Specific
Physiological
Gravity or
Effect*
Vapor
60 Min.
Density
Exposure
Air = 1
0.60
Causes throat and
eye irritation at
0.05%, coughing
at 0.17%. Short
exposure at 0.5%
to 1% fatal.
2.77
Slight symptoms
after several hours
exposure at 0.16% to 0.32%.
2% rapidly fatal.
2.64
Very poisonous,
irritating, vomiting,
convulsions, psychic distur-
bance.
S may be released by the stirring up of
2
Max
Max.
Explosive
Likely
Safe
Safe
Range
Location
8 Hour
(% by vol.
of
Exposure
in air.)
Highest
ppm
ppm
Limits
Concentration
lower/upper
300
85
16
Near top.
to
25
Concentrates
500
in closed up-
per spaces
3,000
25
1.3
At bottom
to
7.1
5,000
—
15
1.3
At bottom
44.0
S.
2
S concentrations, flamma-
2
Most
Simplest and
Common
Cheapest
Sources
Safe Method
of Testing
Sewers, chemical
Detectable
feed rooms
odor at low
concentrations
Industrial wastes,
Combustible
varnish, solvents
gas indicator
An insecticide
Combustible
gas indicator
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