male ANSI standard pipe thread, 10 mm 3/8 inch diameter stainless
steel rods and hexagonal nuts with ring gasket, two gaskets
suitable for making a tight joint between the metal and the tubes,
one bronze bushed air flow controller or orifice, one cap to
receive the hexagonal nuts, and one ceramic diffuser tube. All
gaskets shall be of a composition suitable for withstanding the
action of sewage. The connector assembly and cap shall be of baked
epoxy-coated cast iron or stainless steel.
(2) Porous Plastic Tube Diffuser: Tube shall have a body formed
by a U-shaped steel rod which is firmly attached to a threaded
adapter and fabric holder, all elements being completely coated
with vinyl plastic; or tube shall have a body formed by a plastic
inner core and adapter. A tubular flexible synthetic cloth
sheath, closed at one end and open at the other, shall be fitted
around the body and clamped at the open end by a stainless steel
clamp to form the diffusion media. Tube devices shall be thread
mounted on the diffuser header as recommended by the diffuser
manufacturer. Tube shall have an integral control orifice. The
adapter and fabric holder shall be of cast iron.
b.
Coarse Bubble Diffuser: Coarse bubble diffusers shall be of the
non-porous nozzle type. Nozzle devices shall be saddle-mounted or
thread-mounted on a diffuser header as recommended by the diffuser
manufacturer. Nozzle orifice shall be sized for the particular
application to assure proper range of exit velocity and back
pressure. Diffuser parts shall be stainless steel, zinc-coated
steel, molded plastic, or chloroprene. They shall be corrosion
resisting, impact resistant, self-cleaning and non-absorbent. The
diffuser unit shall be provided with an adapter fitting stud for
attaching to the air header where necessary. They shall contain
an anti-backflow device of polyvinyl chloride or neoprene.
Header-diffuser system shall be able to accommodate a wide range
of air flows by varying the orifice opening automatically, or be
selection of orifice size of installation.
2.8.2.2
Diffuser Holder Assembly
**************************************************************************
NOTE: Delete reference to swing-out type when steel
plant only is required. This specification is
structured for steel plant only, concrete plant
only, or steel or concrete plant at the Contractor's
option. Among the factors to be considered are
initial cost, maintenance costs, life expectancy,
and possible need for relocation during period of
useful life. Steel plant is generally more
economical in first cost than concrete plant;
however, maintenance costs may be higher. Concrete
plant would have a higher life expectancy in highly
corrosive soils. Small steel plants are suitable
for relocation. Concrete plant is considered as
plant having outer walls of concrete regardless of
material used for interior walls or partitions.
Steel plants are considered as plants having outer
walls of steel and bottom of steel or concrete
(except that all-steel would be needed for
relocatable plants).
**************************************************************************
SECTION 11375N
Page 36
Previous Page
