Description & Operation
The
Cleveland Controls AFS-951
Differential Pressure Sensing
Switch
is designed to provide precise
operation and convenient features for
industrial and commercial air han-
dling applications. The
AFS-951
can
monitor positive, negative, or differ-
ential pressure (flow) of air and non-
combustible gases, and is commonly
used to monitor combustion air, fur-
nace pressure, ventilating blower op-
eration, inflatable structure pressure,
fume hood operation, bag house air
flow, dirt accumulation in air filters,
and heat-transfer air flow. The
AFS-
951
has a field–adjustable set point
range of 0.05"wc to 12.0"wc.
Common Applications
The most common specific applica-
tion for the
AFS-951
is as a
Low
Draft (Negative Pressure) Cutoff
Safety Switch
for combustion draft
control systems.
The general applications of the
AFS-951
are:
• Low Positive Pressure Cutoff
.
(Shutdown upon insufficient pres-
sure.)
• Low Negative Pressure Cutoff
.
(Shutdown upon insufficient draft.)
• Low Differential Pressure Cutoff
.
(Shutdown upon insufficient differ-
ence between two samples.)
Mounting
The
AFS-951
is available in 3 enclo-
sures designed for surface mounting
on any flat, relatively stable surface
free of vibration. To obtain the low-
est operating set point specification,
the control must be mounted with the
diaphragm vertical (Fig 1).
The standard enclosure has mounting
flanges with four 9/32" mounting
holes as shown on page 4. The
NEMA-4 rated model has mounting
flanges with four 5/16" mounting
holes as shown on page 3. The
NEMA-7/NEMA-9 rated enclosure
has two mounting slots as shown on
page 3.
AFS-951-1
in NEMA-4 rated
Enclosure.
AFS-951
in Standard Enclosure,
rated NEMA-1.
AFS-951-2
in NEMA-7 and
NEMA-9 rated Enclosure.
Cleveland Controls
Division of UniControl Inc.
Adjustable Set Point Air Pressure Sensing Switch
