Product Overview

BulletinAFSA.02 9/96 draft 1
Bulletin AFSA.02
Application
Cleveland Controls Model AFS-A is a
general purpose airflow proving switch
typically applied to package burners, fur-
naces, and fuel-burning equipment. It
accurately senses positive, negative, or
differential air pressure.
General Description &
Operation
The plated housing contains a dia-
phragm, a calibration spring and a snap-
acting SPDT switch.
The sample connections located on each
side of the diaphragm accept .25" OD
metallic tubing via the integral compres-
sion ferrule and nut.
An enclosure cover guards against ac-
cidental contact with the live switch ter-
minal screws and the set point adjusting
screw. The enclosure cover will accept
a .5" conduit connection.
Mounting (see Figure 1)
Select a mounting location which is free
from vibration. The AFS-A must be
mounted with the diaphragm in any ver-
tical plane in order to obtain the lowest
specified operating set point. Avoid
mounting with the sample line connec-
tions in the "up" position. Surface-
mount the switch to a flange via the 1-
inch, -14 externally threaded connec-
tor with pal nut. This connector is also
internally threaded (1/4" - 18 NPT) for
rigid mounting to a pipe nipple.
Air Sampling Connection
(see Figure 2)
The AFS-A is equipped with a 1/4" – 18
NPT female connector ("H" in Figure 2)
and a 1/8" – 27 NPT female connector
("L" in Figure 2). 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' to the com-
puted sample line length to determine
correct pipe size.
Refer to Figure 2 to identify the high
pressure inlet (H) and the low pressure
inlet (L). Select one of the five applica-
tion options listed below, and connect
the sample lines as recommended.
POSITIVE PRESSURE ONLY: Con-
nect the sample line to inlet H; inlet L
ModelModel
ModelModel
Model
AFAF
AFAF
AF
SS
SS
S
AA
AA
A
Air PAir P
Air PAir P
Air P
ressureressure
ressureressure
ressure
Sensing Switch with ASensing Switch with A
Sensing Switch with ASensing Switch with A
Sensing Switch with A
djustable Set Pdjustable Set P
djustable Set Pdjustable Set P
djustable Set P
oint Rangeoint Range
oint Rangeoint Range
oint Range
Cleveland Controls
Division of UniControl, Inc.
Dimensions in Inches
(Millimeters)
(
Figure 3
)
High
Pressure ®
Low
Pressure ®
¬ Inlet H:
Positive Only.
Lower Negative.
Higher Positive
Inlet L:
Negative Only.
Higher
Negative.
Lower
Positive ®
(Figure 2)