(3) Observing the chlorinator. Visible vacuum type chlorinators (bell jar
installations) will begin to bubble air, and other chlorinators will show erratic movements
of rotameter dose indicators.
g. Use of Gas Masks. Gas masks must be provided at a point accessible to the
operator in the event of an emergency. They are usually placed immediately outside
the chlorine room door.
(1) Front-mounted or back-mounted gas masks equipped with a chlorine
type canister may be used with low concentrations of chlorine in air.
(a) Oxygen depletion. This mask will give no protection in areas
deficient in oxygen.
(b) Maintenance of canisters. Canisters should be replaced either
even if they are not exhausted, when either of the canister's seals have been broken or
when the expiration date on the canister has been exceeded.
(2) Self-contained breathing apparatus with a full-face piece and a cylinder
of air or oxygen carried on the body is suitable for high concentrations of chlorine or
depleted oxygen. The apparatus should be the pressure-demand type in which the
pressure inside the face piece is positive during both inhalation and exhalation. The
self-contained breathing apparatus is optional.
(1) Emergency plan. In addition to the general emergency plan, a carefully
devised plan specific for chlorine gas should be posted. Personnel should be drilled in
executing the plan
(2) Human exposure. If a person has been exposed to chlorine gas,
remove him to fresh air and seek medical assistance immediately.
1-14 FILTRATION EQUIPMENT
a. Gravity Sand Filters. The installation of this type of filter for swimming pools
is no longer common practice. The principles of operation and maintenance are similar
to those discussed under pressure sand filters.
b. Rapid Pressure Sand Filters.
(1) Operation. These filters are supplied with a filtering mat of coagulant
material. They are operated 24 hours a day at 3 gallons per square foot per minute until
the difference in pressure between the influent pressure gauge (incoming water) and
the effluent pressure gauge (outgoing water) is in the range of 5 to 7 pounds per square
inch. They should then be backwashed at the rate of 15 gallons per square foot per