UniControl Cleveland Controls AFS-953 Manual

Cleveland Controls
Division of UniControl Inc
Adjustable Set Point Air Pressure Sensing Switch with 20-Second Pre-Purge and 8-Second Time Delay
AFS-953 in Standard
Enclosure, rated NEMA-1.
DESCRIPTION &
OPERATION
The Cleveland Controls AFS-953 Dif-
ferential Pressure Sensing Switch is
designed to provide precise operation
and convenient features for industrial
and commercial air handling applica-
tions. The AFS-953 can monitor posi-
tive, negative, or differential pressure
(flow) of air and noncombustible gases,
and is commonly used to monitor com-
bustion air, furnace pressure, ventilat-
ing blower operation, inflatable struc-
ture pressure, fume hood operation, bag
house air flow, dirt accumulation in air
filters, and heat-transfer air flow. The
AFS-953 has a field–adjustable set
point range of 0.05"wc to 12.0"wc with
a 20-second pre-purge delay and an
8-second (± 3 seconds) time delay re-
lay sequence. The time delay prevents
nuisance shutdowns due to normal draft
fluctuations.
Cleveland Controls
Division of UniControl Inc.
1111 Brookpark Rd
Cleveland OH 44109
AFS-953-1 in NEMA-4 rated
Enclosure.
COMMON
APPLICATIONS
The most common specific application
for the AFS-953 is as a Low Draft
(Negative Pressure) Cutoff Safety
Switch for combustion draft control
systems where individual pre-purge is
needed. In general, the AFS-953 can
be applied as follows:
• Low Positive Pressure Cutoff.
(Shutdown upon insufficient pres-
sure.)
• Low Negative Pressure Cutoff.
(Shutdown upon insufficient
draft.)
• Low Differential Pressure Cutoff.
(Shutdown upon insufficient dif-
ference between two samples.)
MOUNTING
Three NEMA-rated enclosures, de-
signed for surface mounting on any flat,
relatively stable surface free of vibra-
Tel: 216-398-0330
Fax: 216-398-8558
Email:saleshvac@unicontrolinc.com
Web page: http://www.clevelandcontrols.com
Model
AFS–953
.
AFS-953-2 in NEMA-7 and
NEMA-9 rated Enclosure.
tion, are available for the AFS-953. The
standard enclosure has mounting
flanges with four mounting holes
(9/32") as shown in drawing on page 3.
The NEMA-4 rated model has mount-
ing flanges with four 5/16" mounting
holes as shown at top of page 4. The
NEMA-7/NEMA-9 rated enclosure has
two mounting slots as shown at bottom
of page 4. With any of the enclosures,
the AFS-953 must be mounted with
the diaphragm in a vertical plane, to
obtain the lowest operating set point
specification.
PIPING
The field sample line connectors, two
1/4" - 18 NPT female fittings, labeled
H (high) and L (low), are located on
the side of the enclosure as shown in
Figure 1.
Positive Pressure only: Connect
sample line to H; L remains open
to the atmosphere.
Negative Pressure only: Connect
sample line to L: H remains open
to the atmosphere.
Bulletin AFS953.00