Cleveland Controls AFS–442 User manual

Bulletin AFS442.02 1
Model
AFS–442
Air PressureSensing Switch with Adjustable Set Point Range
Dimensions in Inches
(Millimeters)
Application
The Model AFS-442 is a general pur-
pose proving switch designed for
package burner, furnace, fuel-burning
equipment, HVAC and other Energy
Management applications. It may be
used to sense positive, negative, or
differential air pressure.
General Description &
Operation
The plated housing contains a dia-
phragm, a calibration spring and a
snap-acting SPDTswitch.The sample
connections located on each side of
the diaphragm accept 1/8" pipe.
An enclosure cover guards against ac-
cidental contact with the live switch
terminal screws and the set point ad-
justing screw. The enclosure cover will
accept a ½" conduit connection.
Mounting (see Figure 1)
Select a mounting location which is
free from vibration. The AFS-442must
be mounted with the diaphragm in any
Cleveland Controls
Division of UniControl Inc.
(Figure 2)(Figure 1)
vertical plane in order to obtain the
lowest specified operating set point.
Avoid mounting with the sample line
connections in the "up" position. Sur-
face mount via the two 3/16" diameter
holes in the integral mounting bracket.
The mounting holes are 3-7/8" apart.
Air Sampling Connection
(see Figure 2)
The AFS-442 is equipped with two
1/8" – 27 NPT female connectors. For
sample lines of up to 10 feet, 1/8" pipe
is acceptable. For lines up to 20 feet,
use ¼" pipe. For lines up to 60 feet,
use ½" pipe. For each right angle
bend, add 4 feet to the computed
sample line length to determine correct
pipe size.For sample lines of up to 10
feet, ¼" OD tubing is acceptable. For
lines up to 20 feet, use ¼" ID tubing.
For lines up to 60 feet, use ½" ID tub-
ing. Locate the sampling probe a mini-
mum of 1-½ duct diameters down-
stream from the air source. Install the
sampling probe as close to the center
of the airstream as possible. Refer to
Figure 2 to identify the high pressure
inlet (H) and the low pressure inlet
(L). Select one of the five application
options listed below (on page 2), and
connect the sample lines as recom-
mended.

Bulletin AFS442.02 2
Specifications
Model AFS-442 Air Flow Switch
Mounting Position: Mount with the dia-
phragm in any vertical plane.
Set Point Range:
0.05 ± 0.02" w.c. to 2.0"w.c.
Field Adjustable "Operate Range":
0.07" w.c. to 2.0"w.c.
Field Adjustable "Release Range":
0.04" w.c. to 1.9"w.c.
Approximate Switching Differential:
Progressive; increases from 0.02± 0.01"w.c.
at minimum set point to approximately 0.1 "
w.c. at maximum set point.
Measured Media: Air, or combustion by-
products that will not degrade silicone.
Maximum Pressure:
½ psi (0.03 bar)
Operating Temperature Range:
-40F to 180F (-40 to 82C)
Life: 100,000 cycles minimum at ½ psi
maximum pressure each cycle and at maxi-
mum rated electrical load.
Electrical Rating:
300 VA pilot duty at 115 to 277 VAC,
15 amps noninductive to 277 VAC, 60 Hz.
Contact Arrangement: SPDT
Electrical Connections: Screw-type ter-
minals with cup washers.
Conduit Opening: 7/8" diameter opening
accepts ½" conduit.
Sample Line Connectors: 1/8" - 27 NPT
female connectors (2)
Sample Line Connections: Connectors
will accept ¼" OD rigid or semi-rigid tubing.
Approval: UL, FM, CSA, CE
Shipping Weight: 1.2 lbs.
(Figure 3) Electrical Connections
(see Figure 3)
Before pressure is applied to the dia-
phragm, the switch contacts will be in
the deactivated position as shown in
Figure 3.
The snap switch has screw top
terminals with cup washers. Wire alarm
and control applications as shown in
Figure 4.
Field Adjustment
The adjustment range of an AFS-442
Air Switch is 0.05 to 2.0" w.c, ±.02"
w.c. To adjust the set point:
Turn the adjusting screw counter-
clockwise until motion has stopped.
Next, turn the adjusting screw 4 com-
plete turns in a clockwise direction to
engage the spring. From this point, the
next ten turns will be used for the ac-
tual calibration. Each full turn repre-
sents approximately 0.2"w.c.
Please note: To properly calibrate a
Air Switch, a digital manometer or
other measuring device should be
used to confirm the actual set point.
(Figure 4)
Location of Sample Lines for TypicalApplications
Accessories
•Sample line probes.
•Orifice plugs (pulsation dampers).
Pressure Conversion Table
1" H2O = 0.0361 lbs./sq. in. or 0.0735 in.
mercury
1" Hg. = 0.491 lbs./sq. in. or 13.6 in. water
1 psi = 27.7 in. water or 2.036 in. mercury
POSITIVE PRESSURE ONLY: Con-
nect the sample line to inlet H; inlet L
remains open to the atmosphere.
NEGATIVEPRESSURE ONLY: Con-
nect the sample line to inlet L; inlet H
remains open to the atmosphere.
TWO NEGATIVE SAMPLES: Con-
nect the higher negative sample to in-
let L. Connect the lower negative
sample to inlet H.
TWO POSITIVE SAMPLES:
Connect the higher positive sample to
inlet H. Connect the lower positive
sample to inlet L.
ONE POSITIVE AND ONE NEGA-
TIVE SAMPLE: Connectthe positive
sample to inlet H. Connect the nega-
tive sample to inlet L.