Product Overview

Bulletin AFS-271.00
Model
AFS–271
Dimensions inDimensions in
Dimensions inDimensions in
Dimensions in
Inches (Millimeters)Inches (Millimeters)
Inches (Millimeters)Inches (Millimeters)
Inches (Millimeters)
ApplicationApplication
ApplicationApplication
Application
The Model AFS-271 is a general
purpose proving switch designed
for HVAC and Energy Manage-
ment applications. It may be used
to sense positive, negative, or dif-
ferential air pressure.
Description & OperationDescription & Operation
Description & OperationDescription & Operation
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
¼" OD metallic tubing via the in-
tegral compression ferrule and nut.
compression connections. 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. A ¼" OD adapter, suitable for
slip-on flexible tubing is available:
order part number 18311. Locate
the sampling probe a minimum of
1.5 duct diameters downstream
from the air source. Install the sam-
pling 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 from the
five application options listed be-
low, and connect the sample lines
as shown.
Mounting Mounting
Mounting Mounting
Mounting
( F( F
( F( F
( F
igig
igig
ig
. 1). 1)
. 1). 1)
. 1)
Select a mounting location which
is free from vibration. The AFS-
271 must be mounted with the dia-
phragm in any vertical plane in or-
der to obtain the lowest specified
operating set point. Avoid mount-
ing with the sample line connec-
tions in the “up” position. Surface
mount via the two
3
/16" diameter
holes in the integral mounting
bracket. The mounting holes are 3-
7
/8" apart.
Air Sampling Connection Air Sampling Connection
Air Sampling Connection Air Sampling Connection
Air Sampling Connection
(F(F
(F(F
(F
igig
igig
ig
. 2). 2)
. 2). 2)
. 2)
The AFS-271 is designed to accept
firm-wall sample lines of ¼" OD
tubing by means of ferrule and nut
Open–Mounted Adjustable Set Point Air Pressure Sensing Switch
Cleveland ControlsCleveland Controls
Cleveland ControlsCleveland Controls
Cleveland Controls
Division of UniControl IncDivision of UniControl Inc
Division of UniControl IncDivision of UniControl Inc
Division of UniControl Inc
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6.13"
(155)
2.81"
(71)
1.94" (49)
3.88"
(98)
3.25"
(82)
1.63."
(41)
2.87"
(73)
1.38"
(34)
0.44"
(11)
0.71"
(18)
0.78"
(19)
0.19"
(4)
dia
hole
High
Pressure
Inlet