316B
RULE
TELEPHONE
LOG
Name
of
Caller:
John
Sunda,
SAIC
Date:
September
4,
2002
Company
Name:
Johnson
Screens
Street
Address:

City/
State/
ZIP:
New
Brighton,
MN
55112
Person
Contacted:
Hank
Wells
Title:
Sales
Manager
Telephone
#:
651­
638­
3287
Fax
651­
638­
3177
Called
to
inquire
about
airburst
backwash
piping,
particularly
size
for
larger
screens
(
T72,
T84,
T96)
which
is
left
blank
in
their
brochure
table.
He
said
that
the
piping
size
given
for
smaller
screens
is
nominal
sizing.
For
larger
screens
the
required
pipe
size
is
determined
by
site
conditions,
particularly
depth
and
distance.
He
referred
to
them
as
"
blow
pipes."
The
larger
pipes
generally
range
from
12
to
16
inches
in
diameter.
Pipe
materials
are
generally
schedule
10
stainless
steel
or
high
density
polyethylene
but
materials
comprises
only
a
small
portion
of
the
total
installed
costs.
He
confirmed
that
for
larger
screens
one
blow
pipe
is
installed
for
each
screen
and
that
a
separate
pipe
runs
all
the
way
back
to
the
distributor
located
at
the
shoreline
structure
out
of
the
water.
Sometimes
for
smaller
screens
one
pipe
is
connected
to
two
or
more
screens
For
larger
screens
sometimes
two
blow
pipes
are
used
connecting
each
to
opposite
sides
of
the
T.
Operating
pressure
at
the
screen
connection
is
150
psig.

I
inquired
about
whether
they
ever
use
a
single
pipe
with
the
distributor
valving
placed
underwater
near
the
screens.
He
said
that
clients
expect
the
underwater
portion
of
the
system
to
operate
without
much
maintenance
for
a
long
time
(
e.
g.,
20
years)
and
such
an
arrangement
would
not
be
as
reliable.
If
it
failed,
many
screens
could
not
be
backwashed,
if
a
single
blow
pipe
fails
then
only
that
screen
is
affected.

He
has
been
trying
to
obtain
blow
pipe
design
and
installation
costs
from
contractors
but
they
have
been
reluctant
to
share
such
cost
data.
