01.
Chemical Feed Equipment and
Methods. In addition to the requirements in Section
531, fluoride feed equipment shall
meet the following requirements: (3-24-22)
a.
Scales, loss-of-weight recorders or liquid level indicators, as appropriate,
accurate to within five (5) percent of the average daily change in reading
shall be provided for chemical feeds. (3-24-22)
b. The accuracy of chemical feeders used for
fluoridation shall be plus or minus five (5) percent of the intended dose.
(3-24-22)
c. Unsealed storage units
for fluorosilicic acid shall be vented to the atmosphere at a point outside any
building. (3-24-22)
d. Fluoride
compound shall not be added before lime-soda softening or ion exchange
softening. (3-24-22)
e. The point
of application of fluorosilicic acid, if into a horizontal pipe, shall be in
the lower half of the pipe. (3-24-22)
f. A fluoride solution shall be applied by a
positive displacement pump having a stroke rate not less than twenty (20)
strokes per minute, and at a feed rate not less than twenty (20) percent of the
rated capacity of the feed pump. (3-24-22)
g. A spring opposed diaphragm type
anti-siphon device shall be provided for all fluoride feed lines and dilution
water lines. (3-24-22)
h. Except
for constant flow systems, a device to measure the flow of water to be treated
is required. (3-24-22)
i. The
dilution water pipe shall terminate at least two (2) pipe diameters above the
solution tank. (3-24-22)
j. Water
used for sodium fluoride dissolution shall be softened if hardness exceeds
seventy-five (75) mg/l as calcium carbonate. (3-24-22)
k. Fluoride solutions shall be injected at a
point of continuous positive pressure or a suitable air gap provided.
(3-24-22)
l. The electrical outlet
used for the fluoride feed pump shall be interconnected with the well or
service pump. (3-24-22)
m.
Consideration shall be given to providing a separate room for fluorosilicic
acid storage and feed. (3-24-22)
02.
Secondary Controls.
Secondary control systems for fluoride chemical feed devices shall be provided
as a means of reducing the possibility for overfeed; these may include flow or
pressure switches or other devices. (3-24-22)
03.
Dust Control. Provision must
be made for the transfer of dry fluoride compounds from shipping containers to
storage bins or hoppers in such a way as to minimize the quantity of fluoride
dust which may enter the room in which the equipment is installed. The
enclosure shall be provided with an exhaust fan and dust filter which places
the hopper under a negative pressure. Air exhausted from fluoride handling
equipment shall discharge through a dust filter to the outside atmosphere of
the building. (3-24-22)
