Product Overview
DIAPHRAGM OPERATED PRESSURE SWITCH
Visible Set point Adjustment, Compact
DWYER INSTRUMENTS, INC. | dwyer-inst.com94
Reliable and convenient, the Series AP Diaphragm Operated Pressure Switch is
a compact switch for instrument air or other low pressure applications. Visible set
point and external adjustment add convenience. Used on air, non-corrosive gas or
liquid service compatible with wetted parts. Units are available in weather-proof and
explosion-proof housing.
FEATURES/BENEFITS
• Explosion-proof and weatherproof housing provides device protection for outdoor
use or harsh environment operation
• External switch set point adjustment reduces set-up time
APPLICATIONS
• Low pressure applications
• Instrument air
Single Pressure Switches
PRESSURE
2-13/32
[61.13]
2-7/8
[73.03]
1-7/16
[36.52]
4
[101.60]
15/16
[23.81]
4-1/8 [104.78]
1-1/16
[26.99]
4-11/16 [119.36]
5-1/16 [128.69]
3-1/8
[79.71]
1-13/16
[46.05]
7/8 [22.23]
CONDUIT HOLE
Ø7/8 [22.23]
KNOCK-OUT HOLE
[2]Ø1/4
[6.35]
MOUNTING
HOLE WITH
SEALING WIRE
ADJUSTMENT
SCREW WITH
SEALING WIRE
1/4 NPT
SPECIFICATIONS
Wetted Materials: Nylon reinforced
Buna-N and steel. PTFE and 316 SS
optional.
Temperature Limits: -30 to 150°F (-35
to 66°C).
Pressure Limit: See model chart.
Enclosure Rating: General purpose.
Weatherproof and explosion-proof
optional.
Switch Type: SPDT mercury switch or
SPDT snap switch. Other switch types
available.
Electrical Rating: Mercury switch: 4 A
@ 120 VAC/DC, 2 A @ 240 VAC/DC;
Snap switch: 15 A @ 120 VAC, 8 A @
240 VAC, 0.5 A @ 120 VDC, 0.25 A @
240 VDC.
Electrical Connections: Screw
terminal.
Conduit Connection: 7/8˝ (22.23 mm)
hole for 1/2˝ (12.7 mm) conduit hub.
Process Connection: 1/4˝ female NPT.
Mounting Orientation: Vertical for
mercury switch models, any position for
snap switch models.
Set Point Adjustment: External screw.
Weight: General purpose: 2 lb (0.9 kg).
Deadband: See model chart.
Agency Approvals: FM, UL. For FM
consult factory.
SPECIFICATIONS
Service: Air, motor oils, transmission
oils, jet fuels, and similar hydrocarbon
media. (Not for water use)
Wetted Materials: Base: 304 SS;
Diaphragm: Polyamide lm.
Temperature Limits: -40 to 248°F (-40
to 120°C).
Pressure Limits: Operating pressure:
150 psi (10.3 bar) for 0.5-24 psi set point
ranges, 250 psi (17.2 bar) for 25 to150
psi set point ranges; Proof pressure: 500
psi (34.5 bar); Burst pressure: 750 psi
(51.7 bar) for 0.5-24 psi set point ranges,
1250 psi (86.2 bar) for 25-150 psi set
point ranges.
Enclosure Rating: General purpose or
with cover: IP65 - weatherproof.
Repeatability: ±10% of set point.
Set Point Tolerance: ±15% of range.
Switch Type: 1 SPST NO, 1 SPST NC.
NO and NC switch independent from
each other.
Electrical Ratings: Resistive: 15 A @ 6
VDC, 8 A @ 12 VDC, 4 A @ 24 VDC;
Inductive: 1 A @ 120 VAC, 0.5 A @ 240
VAC.
Electrical Connections: #8-32 screw
terminals.
Process Connection: 1/4˝ NPT male.
Mounting Orientation: Switch can be
installed in any position.
Set point Adjustment: Screw.
Weight: 0.13 lb (0.06 kg).
DURABLE PRESSURE SWITCHES
Designed for Extended Duty, Simple and Reliable
Series A6 Durable Pressure Switches have been specically designed to stand up
to extended duty applications. These switches are constructed with a polyimide lm
diaphragm and are compatible with a variety of uids. For ease of installation, the
switches come with a 1/4˝ male NPT process connection and can be mounted in any
orientation. The Series A6 pressure switches are compact and have great set point
integrity, and feature simple, easy set point eld adjustment.
FEATURES/BENEFITS
• High switch cycle means long life for extended duty applications
• Mounting in any position and feature simple makes a reliable switching for equipment
and OEM applications
APPLICATIONS
• OEM
2-7/16
[62]
#8-32 SCREW
TERMINALS
ø1.500
[ø38.1]
2-5/16
[58.74]
ø1-1/2 [ø38.1]
2
[50.8]
ø1-1/2
[ø38.1]
1/4˝ NPT
A-439 A-439A-440 A-440
SERIES A6 | MERCOID
®
BY DWYER
SERIES AP | MERCOID
®
BY DWYER
USA: California Proposition 65
WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov
• Process equipment
• Process applications
ACCESSORIES
Model Description
A-439
A-440
Weatherproof IP65 cover
Weatherproof IP65 with y-wire holes
MODEL CHART
Model
Switch* Type
SPDT Ranges
Switch Deadband
Max. Press.
psig(bar)Low High
AP-153-33
AP-153-37
AP-153-39
AP-7021-153-33
AP-7021-153-37
AP-7021-153-39
Mercury
Mercury
Mercury
Snap
Snap
Snap
10 in VAC to 50 in w.c. (2.5 to 12.4 kPa)
1 to 30 psig (.07 to 2.1 bar)
10 to 125 psig (.69 to 8.6 bar)
10 in VAC to 50 in w.c. (2.5 to 12.4 kPa)
1 to 30 psig (.07 to 2.1 bar)
10 to 125 psig (.69 to 8.6 bar)
5 in w.c. (1.2 kPa)
0.4 psig (0.03 bar)
2 psig (0.14 bar)
8 in w.c. (2.0 kPa)
0.75 psig (0.05 bar)
3 psig (0.21 bar)
6 in w.c. (1.49 kPa)
0.75 psig (0.05 bar)
6 psig (0.04 bar)
10 in w.c. (2.49 kPa)
1.5 psig (0.10 bar)
7 psig (0.48 bar)
15 (1.03)
60 (4.14)
160 (11.0)
15 (1.03)
60 (4.14)
160 (11.0)
*Mercury switch units are not CE approved.
MODEL CHART
Model
Set Point Range psi (bar)
NC NO
A6-153221
A6-253221
A6-353221
A6-453221
A6-553221
A6-653221
A6-753221
A6-853221
0.5 to 1 (0.03 to 0.07)
1.1 to 3 (0.08 to 0.21)
3.1 to 7 (0.21 to 0.48)
8 to 13 (0.55 to 0.90)
14 to 24 (0.97 to 1.66)
25 to 50 (1.73 to 3.45)
51 to 90 (3.52 to 6.21)
91 to 150 (6.28 to 10.35)
1.1 to 3.1 (0.08 to 0.21)
2.27 to 6.05 (0.16 to 0.42)
4.22 to 10.75 (0.29 to 0.74)
12.3 to 17.5 (0.85 to 1.21)
18.6 to 31.8 (1.28 to 2.19)
33.1 to 61 (2.28 to 4.21)
65.6 to 112.3 (4.53 to 7.75)
114.7 to 198.3 (7.94 to 13.68)
Pressure_2021.indb 94 7/15/20 8:19 AM