Product Overview

Bulletin LTAFS228-02
Cleveland Controls
DIVISION OF UNICONTROL INC.
1111 Brookpark Rd
Cleveland OH 44109
Tel: [phone]
Fax: [phone]
Email:[e-mail]
Web page: http://www.clevelandcontrols.com
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Cleveland Controls
Division of UniControl Inc.
APPLICATION
Model AFS-228 Air Pressure Sensing Switch
is a general purpose proving switch de-
signed for HVAC and Energy Management
applications. It may be used to sense posi-
tive, negative, or differential air pressure.
GENERAL DESCRIPTION &
OPERATION
The plated housing contains a diaphragm, 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 integral compression
ferrule and nut.
MOUNTING (SEE FIGURE 1)
Select a mounting location which is free from
vibration. The AFS-228 must be mounted
with the diaphragm in any vertical plane in
order to obtain the lowest specifi ed operating
set point. Avoid mounting with the sample
line connections in the "up" position. Surface
mount via the two
3
/16" diameter holes in the
integral mounting bracket. The mounting
holes are 3-⅞" apart.
The AFS-228 is designed to accept fi rm-wall
sample lines of ¼" OD tubing by means of
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 tubing. A ¼" OD adapter, suitable for
slip-on fl exible 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 sampling probe as close
to the center of the airstream as possible.
Refer to Figure 2 to identify the high pres-
sure inlet (H) and the low pressure inlet (L).
Select one of the fi ve application options
listed below, and connect the sample lines
as recommended.
POSITIVE PRESSURE ONLY: Connect the
sample line to inlet H; inlet L remains open
to the atmosphere.
NEGATIVE PRESSURE ONLY: Connect
the sample line to inlet L; inlet H remains
open to the atmosphere.
TWO NEGATIVE SAMPLES: Connect the
higher negative sample to inlet 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 NEGATIVE
SAMPLE: Connect the positive sample
to inlet H. Connect the negative sample
to inlet L.
Model
AFS–228
OPEN-MOUNTED AIR PRESSURE SENSING SWITCH WITH ADJUSTABLE SET POINT RANGE
AIR SAMPLING CONNECTION
(SEE FIGURE 2)
(Figure 1)