13
Fact:
An
unacceptable
(high)
pressure
loss
ratio
(PLR)
is
the
primary
cause
of
poor
mixing
valve/hose
station
performance.
Symptoms
of
a
high
PLR
may
include
1. Inability
to
obtain
hot
water
2. Inability
to
accurately
adjust
outlet
temperature
3. Inability
to
stabilize
outlet
temperature
4. Noisy
operation
or
"
chattering
"
Results
of
a
high
PLR
may
include
1. Premature
component
failure
2. Unsafe
outlet
water
temperatures
3. Poor
overall
product
performance
To
diagnose
a
high
PLR
1. Identify
static
inlet
steam
and
water
pressures
at
point
of
installation.
Note
any
inlet
pressure
differentials
greater
than
2:1
ratio.
2. Remove
primary
outlet
restriction
(remove
spray
nozzle
for
example)
3. Uncoil
hose
completely
and
ensure
that
there
are
no
kinks
or
blockages.
4. Operate
Hose
Station
and
record
performance.
Correcting
high
PLR
1. Install
Pressure
regulator(s)
and
reduce
inlet
pressure
differential*
2. Permanently
reduce
back
pressure/restriction
by
a)
using
shorter
or
less
restrictive
hose;
b)
using
a
less
restrictive
nozzle
(consult
Armstrong
Hot
Water
Group
for
details
on
our
16
and
22
gpm
spray
nozzles)
3. Ensure
that
outlet
components
such
as
extension
wands
and
hose
reels
are
not
significantly
impeding
flow.
*Consult
flow
charts
on
page
7
to
ensure
that
you
maintain
adequate
supply
pressures
for
the
application.
