Dwyer Instruments Series 1640 Part Numbering Designation

Series 1640 | Floating Contact Null Switch for High and Low Actuation which applies to damper positioning and duct air control. For use

…

Damper positioning Duct air control

The unique electric switch design in the Series 1640 is another Dwyer Instrument, Inc.

innovation. The Dwyer® Series 1640 Differential Pressure Switch resembles the Series 1630

switches. However, the Series 1640 is equipped with a single pole, double throw floating contact

switch (not snap acting) so it functions as a null switch.

As the diaphragm moves in response to pressure changes, it moves the floating contact to cause

switching action at two preset points with no switching action between these points. The "high"

circuit will be closed when rising pressure differential reaches the preset level. The "low" circuit

will be closed when falling pressure differential reaches the preset level.

A typical example of usage is to position motorized dampers when static pressure in a duct

system reaches a desired maximum and reposition the dampers when the static pressure falls to

a pre-established minimum. By using a Pitot tube sensing element the Series 1640 switch can

serve in the same way to control air velocity and maintain a constant volume of air in a supply

duct.

CAUTION: FOR USE ONLY WITH AIR OR COMPATIBLE GASES.

Product Applications

Model Chart

EXAMPLE 1640 0 AT

Series 1640-0-AT Floating Contact Null Switch for High and Low Actuation, range 0.01-0.2"
w.c., with aluminum tag.

SERIES 1640   Floating Contact Null Switch for High and Low Actuation

RANGE 

0
1
2
5
10
.25KPA
1KPA

1.5KPA
3KPA



0.01 - 0.2" w.c.

0.20-1.0" w.c.

1.0-4.0" w.c.

2.0-6.0" w.c.

3.0-12.0" w.c.

0.05-0.25 kPa

0.4-1.0 kPa

0.5-1.5 kPa

1.0-3.0 kPa

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Series 1640 Floating Contact Null Switch for High
and Low Actuation

Visual Set Point Adjustment, Adjustable Null Zone

1/2

Series 1640 | Floating Contact Null Switch for High and Low Actuation which applies to damper positioning and duct air control. For use

…

2/2

OPTIONS   AT

LC
PRESET
ST

Aluminum Tag
Less Conduit
Preset
Stainless Steel Tag