Product Overview

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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Bulletin DFS221.05
Cleveland Controls
Division of UniControl Inc.
(Figure 1)
Model
DFS–221
AIR PRESSURE SENSING SWITCH WITH FIXED SET POINT RANGE
APPLICATION
Model DFS–221 is an airflow proving
switch designed for duct heater, oven,
and other HVAC or Energy Management
applications where an open-mounted,
nonadjustable switch is desirable. It is es-
pecially suitable for surface-mounting in
areas where internal access is limited. It
can be used to sense positive, negative,
or differential air pressure. The DFS–221
is equipped with a convenient barbed
sample line connector that accepts flex-
ible tubing.
GENERAL DESCRIPTION &
OPERATION
The plated housing contains a diaphragm
and a snap-acting SPDT switch. The
barbed sample line connections located
on each side of the diaphragm accept
flexible tubing. The electrical connection
consists of male 1/4-inch quick connect
terminals.
The SPDT snap action switch operates
on pressure rise of 0.05"w.c., + 0.02" w.c.
For additional application and technical
information, please contact the sales of-
fice.
MOUNTING
(FIGURE 1)
Select a mounting location which is free
from vibration. The DFS–221 must be
mounted with the diaphragm in any verti-
cal plane in order to maintain the speci-
fied operating set point. Avoid mounting
with the sample line connections in the
"up" position. Surface mount via the two
3/16" diameter holes on the zinc-plated
strap bracket. The mounting holes are 3-
7/8" apart.
AIR SAMPLING
CONNECTION
(FIGURE 2)
The DFS–221 is equipped with two 1/4"
slip-on sample line connections, situated
on either side of the diaphragm as shown
in Figure 2. These connections are suit-
able for flexible tubing.
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 pressure inlet (H) and the low pres-
sure inlet (L). Select one of the five appli-
cation 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. Con-
nect 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.
Mount with the diaphragm in any vertical
plane.