Powers
TM
Controls
Technical Instructions
Document No. 155-052P25
SW 141-1
June 17, 2010
SW 141 Differential Static
Airflow Switches
141-0518
Siemens Industry, Inc.
Description
The SW 141 Airflow Switch senses static differential pressure and the diaphragm operated
snap switches actuate electrical circuits. Auto reset and manual reset models are
available.
Application
Auto reset switches (141-0518 and 141-0574) should be used for applications requiring
positive proof of airflow (or fan operation) or to detect high differential pressures
associated with dirty air filters or similar maintenance alarms not requiring safety lock-out
(shut down) of the fan.
The manual reset switch (141-0575) should be used for applications requiring safety lock
out (shut down) of the fan. The switch can be used on the fan discharge (positive
pressure), fan inlet (negative pressure), or across the fan (differential pressure) to detect
excessively high positive pressures or low negative pressures, and turn off the fan before
damage occurs to ducts or dampers.
Product Numbers
Table 1.
Product
Number
Setpoint Range
(Field Adjustable)
Setpoint *
Accuracy
Switching *
Differential
Switching
Action
141-
0518
1” to 12” WC
(250 Pa to 3000 Pa)
@ 12”
±
1.5” WC
(3000 Pa
±
375
Pa)
Approx.
0.6” to 1.5” WC
(150 Pa to 375 Pa)
SPDT/
Auto Reset
141-
0575
1” to 12” WC
(250 Pa to 3000 Pa)
@ 12”
±
1.5” WC
(3000 Pa
±
375
Pa)
Not Applicable
SPST/
Manual
Reset
141-
0574
0.05” to 1.0” WC
(12.5 Pa to 250 Pa)
@ 1”±0.2“ WC
(250 Pa
±
50 Pa)
Approx.
0.06
"
to 0.6” WC
(15 Pa to 150 Pa)
SPDT/
Auto Reset
*
Setpoint accuracy
tolerance
and switching differential decrease proportional to setpoint decrease.
