COMPACT, RUGGED, ADJUSTABLE
PRESSURE AND VACUUM SWITCHES
PSW21 Series
PSW22 Series
U Adjustable Setpoint
1
U
⁄8 NPT or Center Spout
for
U Pressure and Vacuum Models Available
U UL Recognized, CSA Certified Up to 25 A
1
⁄8 ID Tubing
These compact pressure and vacuum switches are designed
and manufactured to exacting standards to meet the needs
of OEM manufacturers and instrument makers for a low-cost,
stable, repeatable switch. Plastic mechanisms and housings
are acetal to minimize moisture absorption and maintain
dimensional stability. Plastic welding is accomplished using
advanced microprocessor-controlled, ultrasonic welding
equipment. All switches are 100% tested at high and low settings
and at the proof pressure. Units are delivered with the setpoint
at approximately the midpoint of the adjustable range.
SPECIFICATIONS
Approval: UL-recognized,
CSA-certified switches; microswitches
bear the CE and ENEC mark
Temperature Range: -10 to 70°C
(14 to 158°F)
Setpoint Accuracy:
±10% of setting at 21°C (70°F)
Note: Pressure settings may change over the
temperature range.
Hysteresis (Deadband):
15 to 25% of the setpoint
Electrical: See table (page H-8) for
the switch amp rating, 250 Vac
Terminals: 6.35 mm (0.25") standard
“slide-on” male
Materials of Construction
Body and Mechanism: Acetal
Diaphragm: EPDM
(ethylene-propylene diene monomer)
Screws: Stainless or zinc-plated steel
Springs: Stainless steel
Media Compatibility: Air, water and
many other fluids and gases that are
compatible with EPDM and acetal
Note: Mineral oil and similar fluids are not
compatible with EPDM. Request nitrile
diaphragm (see “Custom Switches” on
next page).
Weight: 50 g (1.8 oz)
Overall Dimensions: Approx
54 x 76 x 45 mm (2.125 x 3 x 1.75")
PSW22(*)D
Shown larger
than actual size.
PSW21(*)
Setting: The pressure switch is field
adjustable using the hex head set screw
at the center of the pressure switch
(PSW 21/22-WRENCH). The vacuum
switch is field adjustable using the
Phillips head screw on the switch carrier.
Dual Pressure Switch: The DPDT
(2 switches) will both change state at
approximately the same setpoint. On
DPDT units, one switch may be set
to lead or lag the other (see “Custom
Switches” on next page).
To Order
PRESSURE SWITCHES PSW21,
MODEL NO. ADJUSTABLE RANGE PROOF PRESSURE SPDT SWITCH RATING
PSW21A 3 to 7 inH2O 20 psig 3 A (resistive)
PSW21B 5 to 35 inH2O 20 psig 5 A (resistive)
PSW21C 1 to 6 psig 50 psig 21 A (resistive)
PSW21D 4 to 11 psig 50 psig 25 A (resistive)
PSW21E 9 to 18 psig 50 psig 25 A (resistive)
PSW21F 15 to 28 psig 50 psig 25 A (resistive)
PSW21G 25 to 40 psig 200 psig 25 A (resistive)
PSW21H 35 to 65 psig 200 psig 25 A (resistive)
PSW21J 50 to 100 psig 200 psig 25 A (resistive)
PSW21K 75 to 120 psig 200 psig 25 A (resistive)
Visit omega.com/psw21_psw22 for Pricing and Details
1
⁄
8 MNPT with
9
⁄
16 Threaded Mounting Nut Included
H-7
ADJUSTABLE PRESSURE AND VACUUM SWITCHES
PSW21(*)D
PSW22(*)
All products shown
smaller than actual size.
ACCESSORIES
PSW21/22-WRENCH
Allen wrench for adjusting
pressure switches only, $1;
vacuum switch is adjusted
with a Phillips head screwdriver
CUSTOM SWITCHES
Custom pressure switches are
available–50 piece minimum
order; consult Pressure
Engineering for price and
delivery
Custom Options:
Factory setting available
at specified setpoint
Switch Body: Noryl
Diaphragm: Nitrile
DPDT: Switch can be factory set
so that each switch operates at
a different pressure setting.
®
PRESSURE SWITCHES PSW21
1
⁄
8 MNPT with
9
⁄
16 Threaded Mounting Nut Included
ADJUSTABLE PROOF DPDT SWITCH
MODEL NO. RANGE PRESSURE RATING
PSW21BD 10 to 35 inH
O 250 inH2O 5 A (resistive)
2
PSW21CD 1 to 6 psig 50 psig 21 A (resistive)
PSW21DD 4 to 11 psig 50 psig 25 A (resistive)
PSW21ED 9 to 18 psig 50 psig 25 A (resistive)
PSW21FD 15 to 28 psig 50 psig 25 A (resistive)
PSW21GD 25 to 40 psig 200 psig 25 A (resistive)
PSW21HD 35 to 65 psig 200 psig 25 A (resistive)
PSW21JD 50 to 100 psig 200 psig 25 A (resistive)
PSW21KD 75 to 120 psig 200 psig 25 A (resistive)
1
PRESSURE SWITCHES PSW22 Center Spout for
⁄
8
ID tubing with
9
⁄
16
Threaded Mounting Nut & Tube Lock Nut Included
ADJUSTABLE PROOF SPDT SWITCH
MODEL NO. RANGE PRESSURE RATING
PSW22A 3 to 7 inH2O 250 inH2O 3 A (resistive)
PSW22B 5 to 35 inH2O 250 inH2O 5 A (resistive)
PSW22C 1 to 6 psig 50 psig 21 A (resistive)
PSW22D 4 to 11 psig 50 psig 25 A (resistive)
PSW22E 9 to 18 psig 50 psig 25 A (resistive)
PSW22F 15 to 28 psig 50 psig 25 A (resistive)
1
PRESSURE SWITCHES PSW22 Center Spout for
ADJUSTABLE PROOF DPDT SWITCH
⁄
8
ID tubing with
9
⁄
16
Threaded Mounting Nut & Tube Lock Nut Included
MODEL NO. RANGE PRESSURE RATING
PSW22BD 10 to 35 inH2O 250 inH2O 5 A (resistive)
PSW22CD 1 to 6 psig 50 psig 21 A (resistive)
PSW22DD 4 to 11 psig 50 psig 25 A (resistive)
PSW22ED 9 to 18 psig 50 psig 25 A (resistive)
PSW22FD 15 to 28 psig 50 psig 25 A (resistive)
VACUUM SWITCHES PSW21
ADJUSTABLE PROOF SPDT SWITCH
1
⁄
8 MNPT with
9
⁄
16
Threaded Mounting Nut Included
MODEL NO. RANGE PRESSURE RATING
PSW21L 3 to 7 inWC Vac 350 inWC Vac 3 A (resistive)
PSW21M 6 to 16 inWC Vac 350 inWC Vac 10 A (resistive)
PSW21N 13 to 25 inWC Vac 350 inWC Vac 21 A (resistive)
PSW21P 20 to 40 inWC Vac 350 inWC Vac 21 A (resistive)
PSW21Q 35 to 80 inWC Vac 350 inWC Vac 21 A (resistive)
PSW21R 75 to 150 inWC Vac 350 inWC Vac 21 A (resistive)
PSW21T 145 to 300 inWC Vac 350 inWC Vac 21 A (resistive)
VACUUM SWITCHES PSW21
ADJUSTABLE PROOF DPDT SWITCH
1
NPT with
⁄
8
9
Threaded Mounting Nut Included
⁄
16
MODEL NO. RANGE PRESSURE RATING
PSW21MD 6 to 16 inWC Vac 350 inWC Vac 10 A (resistive)
PSW21ND 13 to 25 inWC Vac 350 inWC Vac 21 A (resistive)
PSW21PD 20 to 40 inWC Vac 350 inWC Vac 21 A (resistive)
PSW21QD 35 to 80 inWC Vac 350 inWC Vac 21 A (resistive)
PSW21RD 75 to 150 inWC Vac 350 inWC Vac 21 A (resistive)
PSW21TD 145 to 300 inWC Vac 350 inWC Vac 21 A (resistive)
Ordering Example: PSW21D, adjustable pressure switch for setpoints between 4 and 11 psig, with 25 A
SPDT switch.
PRESSURE SWITCHES
H
H-8
PRESSURE, VACUUM, AND
DIFFERENTIAL SWITCHES
PRINTED CIRCUIT BOARD MOUNTABLE
PSW23 Series
PSW24 Series
PSW25 Series
U UL Recognized,
CSA Certified
U Printed Circuit
Board Mountable
U Leads Available
as an Option
U Several Fitting Styles
Available
U Pressure, Vacuum,
and Differential
Models Available
U Fixed Setpoint
PSW23-(*)
All products
shown larger
than actual size.
PSW25-(*)
PSW24-(*)
These miniature single-pole
switches are used in pressure
and vacuum applications in which
moderate accuracy is sufficient.
The fixed setpoint is factory set.
SPECIFICATIONS
Temperature Range:
-10 to 75°C (14 to 167°F)
Setpoint Accuracy:
±10% of setting at 21°C (70°F)
Note: Pressure settings may change
over the temperature range.
Materials of Construction
Lower Body: Rynite plastic (with pin
terminals molded in)
Upper Body: Acetal plastic
Diaphragm: EPDM (ethylene-propylene
diene monomer)
Internal Parts: Acetal plastic
Screws: Stainless steel or zinc-plated
steel, flash
Contacts: SPST (normally open); gold
flash over silver-plated copper alloy
Pins: Gold flash over silver-plated
copper alloy
Leads [Optional (-L)]: 8", 20 AWG
stranded PVC-insulated wire fastened to
the switch terminals
Electrical: SPST (NO), 1 A resistive
250 Vac; ratings are dependent on
actuation pressure and must be derated
at lower pressures (under 1 psi).
Pressure Connection
PSW23: 1⁄8 MNPT
PSW24: Center spout for 1⁄8 ID tubing;
provided with 9⁄16-18 mounting nut.
PSW25: Radial spout for 1⁄8 ID tubing
Proof Pressure: See table
Hysteresis (Deadband): Negligible
Media Compatibility: Air, water and
many other fluids and gases that are
compatible with EPDM acetal plastic
To Order
PRESSURE MODELS PSW23
MODEL NO. FIXED SETPOINT PROOF PRESSURE
PSW23-10W 10 inH2O 250 inH2O
PSW23-20W 20 inH2O 250 inH2O
PSW23-1P 1 psig 40 psig
PSW23-2P 2 psig 40 psig
PSW23-10P 10 psig 40 psig
PSW23-20P 20 psig 40 psig
PSW23-30P 30 psig 60 psig
Ordering Example: PSW23-10P, fixed setpoint of 10 psig.
Visit omega.com/psw21_psw22 for Pricing and Details
1
⁄8 MNPT with 9⁄16 Threaded Mounting Nut Included
H-9
Note: Mineral oil and similar fluids are not
compatible with EPDM. Request nitrile
diaphragms (see “Custom Switches” on next
page). Contacts are exposed to media on
base spout.
Overall Dimensions:
38 x 25 mm (1.5 x 1")
Pin Spacing: 12.7 mm (0.5") centers
Weight: 6 g (0.2 oz)
Approvals: UL-recognized,
CSA-certified switches
PRESSURE, VACUUM, AND DIFFERENTIAL SWITCHES
PSW23-(*)-L
Note:
On vacuum
models,
black side
spout is the
vacuum port
PSW23-(*)-L
VACUUM MODELS PSW23V
1
MNPT with
⁄
8
9
Threaded Mounting Nut Included
⁄
16
MODEL NO. FIXED SETPOINT PROOF PRESSURE
PSW23V-10W 10 inWC Vac 300 inWC Vac
PSW23V-20W 20 inWC Vac 300 inWC Vac
PSW23V-50W 50 inWC Vac 300 inWC Vac
PSW23V-100W 100 inWC Vac 300 inWC Vac
PSW23V-200W 200 inWC Vac 400 inWC Vac
PRESSURE MODELS PSW24 Center Spout for
with 9⁄16 Threaded Mounting Nut and Tube Lock Nut Included
1
ID Tubing,
⁄
8
MODEL NO. FIXED SETPOINT PROOF PRESSURE
PSW24-10W 10 inH2O 250 inH2O
PSW24-20W 20 inH2O 250 inH2O
PSW24-1P 1 psig 40 psig
PSW24-2P 2 psig 40 psig
PSW24-10P 10 psig 40 psig
PSW24-20P 20 psig 40 psig
VACUUM MODELS PSW24V Center Spout for
Mounting Nut and Tube Lock Nut Included
1
ID Tubing, with
⁄
8
9
Threaded
⁄
16
MODEL NO. FIXED SETPOINT PROOF PRESSURE
PSW24V-10W 10 inWC Vac 300 inWC Vac
PSW24V-20W 20 inWC Vac 300 inWC Vac
PSW24V-50W 50 inWC Vac 300 inWC Vac
PSW24V-100W 100 inWC Vac 300 inWC Vac
PSW24V-200W 200 inWC Vac 400 inWC Vac
PRESSURE SWITCHES
H
PSW24-(*)-L
All products shown
smaller than actual size.
PSW25-(*)-L
PRESSURE MODELS PSW25 Radial Spout for
1
ID Tubing
⁄
8
MODEL NO. FIXED SETPOINT PROOF PRESSURE
PSW25-10W 10 inH2O 250 inH2O
PSW25-20W 20 inH2O 250 inH2O
PSW25-1P 1 psig 40 psig
PSW25-2P 2 psig 40 psig
PSW25-10P 10 psig 40 psig
PSW25-20P 20 psig 40 psig
To order with 8" 20 AWG leads; add suffix “-L” to model number for additional cost.
Ordering Example: PSW23V-10W-L, vacuum switch with a fixed setpoint of 10 inH2O
vacuum,
CUSTOM SWITCHES
Custom pressure switches are available–
50 piece minimum order; consult Pressure
Engineering for price and delivery
Custom Options: Pre-fixed setpoints
1
NPT pressure port, 8" 20 AWG leads.
⁄
8
Diaphragm: Nitrile
Leads: Custom length
Electrical: SPST, normally closed
Vacuum Switches: Vacuum port at top
instead of black side spout (NC only)
other than those in the tables
H-10
PRESSURE AND VACUUM SWITCHES
COMPACT, RUGGED, PRE-FIXED SETPOINT
PSW27 Series
PSW28 Series
PSW29 Series
U UL Recognized, CSA
Certified Up to 21 A
U Fixed Setpoint
U Pressure and Vacuum
Models Available
U 1⁄8 NPT or Spout for
1⁄8 ID Tubing
These reliable, compact,
single-pole switches are used
in pressure and vacuum
applications in which moderate
accuracy is sufficient. The fixed
setpoint is factory set.
PSW29 shown larger
than actual size.
PSW27 shown larger
than actual size;
Noryl® option shown.
PSW28 shown
larger than
actual size.
SPECIFICATIONS
Approvals: UL recognized,
CSA certified; microswitches
bear the ENEC and CE mark
Temperature Range:
-10 to 75°C (14 to 167°F)
Setpoint Accuracy:
±10% of setting at 21°C (70°F)
Note: Pressure settings
may change over the
temperature range.
Electrical: SPDT; see To Order chart
on next page for amp rating, 250 Vac
Electrical Connection
Terminals: 6.35 mm (0.25")
standard “slide-on” male
Proof Pressure: Maximum system
pressure, see To Order chart
on next page
Materials of Construction
Body: Acetal
Diaphragm: EPDM (ethylene-propylene
diene monomer)
Pressure Connection
PSW27: 1⁄8 MNPT
PSW28: Center spout for
provided with
and tube lock nut
PSW29: Radial spout for
through-hole legs
for mounting bolt
Proof Pressure: See To Order chart
on next page
Hysteresis (Deadband)
Pressure Switches:
Approximately 25% of the setpoint
Vacuum Switches:
Approximately 30% of the setpoint
Media Compatibility: Air, water and
many other fluids and gases that are
compatible with EPDM and acetal
Note: Mineral oil and similar fluids are not
compatible with EPDM. Request
diaphragm (see “Custom Switches").
9
⁄16-18 threaded mounting
1
⁄8" ID tubing;
1
⁄8" ID tubing;
nitrile
H-11
Weight: 0.6 oz (17 g)
Overall Dimensions:
45 x 51 x 25 mm (1.75 x 2 x 1")
CUSTOM SWITCHES
Custom pressure switches are available;
50 piece minimum order; consult
Pressure Engineering for price and
delivery
Custom Options:
Pre-fixed setpoints other than those
in the tables
Body: Noryl® available on custom
order (see photo of PSW27 above)
Diaphragm: Nitrile is available
on custom order.
PRESSURE AND VACUUM SWITCHES
To Order
PRESSURE SWITCHES PSW27
Visit omega.com/psw21_psw22 for Pricing and Details
1
MNPT
⁄
8
MODEL NO. FIXED SETPOINT PROOF PRESSURE SPDT SWITCH RATING
PSW27-1P 1 psig 30 psig 10 A (resistive)
PSW27-2P 2 psig 50 psig 21 A (resistive)
PSW27-5P 5 psig 50 psig 21 A (resistive)
PSW27-10P 10 psig 50 psig 21 A (resistive)
PSW27-20P 20 psig 50 psig 21 A (resistive)
PSW27-30P 30 psig 80 psig 21 A (resistive)
PSW27-40P 40 psig 80 psig 21 A (resistive)
PSW27-50P 50 psig 80 psig 21 A (resistive)
VACUUM SWITCHES PSW27V
1
MNPT
⁄
8
MODEL NO. FIXED SETPOINT PROOF PRESSURE SPDT SWITCH RATING
PSW27V-25W 25 inWC Vac 300 inWC Vac 10 A (resistive)
PSW27V-30W 30 inWC Vac 300 inWC Vac 10 A (resistive)
PSW27V-40W 40 inWC Vac 300 inWC Vac 21 A (resistive)
PSW27V-50W 50 inWC Vac 300 inWC Vac 21 A (resistive)
PSW27V-75W 75 inWC Vac 350 inWC Vac 21 A (resistive)
PSW27V-100W 100 inWC Vac 350 inWC Vac 21 A (resistive)
PSW27V-150W 150 inWC Vac 350 inWC Vac 21 A (resistive)
PSW27V-200W 200 inWC Vac 350 inWC Vac 21 A (resistive)
Note: PSW27V vacuum switches have ±20% field adjustment. Inside the
the setpoint approx. ±20%. The setting is considered “NO-Tamper”, because when installed, there is no access to this adjustment.
1
NPT fitting, locate the set screw. Turning the set screw will adjust
⁄
8
PRESSURE SWITCHES
H
PRESSURE SWITCHES PSW28 Center Spout for
1
ID Tubing with
⁄
8
9
-18 Threaded Mounting and Tube Lock Nut Included
⁄
16
MODEL NO. FIXED SETPOINT PROOF PRESSURE SPDT SWITCH RATING
PSW28-1P 1 psig 30 psig 10 A (resistive)
PSW28-2P 2 psig 50 psig 21 A (resistive)
PSW28-5P 5 psig 50 psig 21 A (resistive)
PSW28-10P 10 psig 50 psig 25 A (resistive)
PSW28-20P 20 psig 50 psig 25 A (resistive)
PSW28-30P 30 psig 80 psig 25 A (resistive)
PSW28-40P 40 psig 80 psig 25 A (resistive)
PSW28-50P 50 psig 80 psig 25 A (resistive)
PRESSURE SWITCHES PSW29 Radial Spout for
1
ID Tubing
⁄
8
MODEL NO. FIXED SETPOINT PROOF PRESSURE SPDT SWITCH RATING
PSW29-1P 1 psig 30 psig 10 A (resistive)
PSW29-2P 2 psig 50 psig 21 A (resistive)
PSW29-5P 5 psig 50 psig 21 A (resistive)
PSW29-10P 10 psig 50 psig 21 A (resistive)
PSW29-20P 20 psig 50 psig 21 A (resistive)
PSW29-30P 30 psig 50 psig 21 A (resistive)
Ordering Example: PSW27-10P, pressure switch with fixed setpoint at 10 psig, deadband of approx. 2.5 psig (25% of the fixed setpoint) with a
1
MNPT pressure port.
⁄
8
H-12
SENSITIVE PRESSURE, VACUUM, OR
DIFFERENTIAL PRESSURE SWITCHES
PSW20 Series
These sensitive singlepole switches can be used
as pressure, vacuum, or
differential switches.
PSW20A shown larger
than actual size.
SPECIFICATIONS
Approvals: UL recognized,
CSA certified
Temperature: -30 to 65°C
(-23 to 149°F)
Setpoint Accuracy:
±10% of setting at 21°C (70°F)
Note: Pressure settings may change over the
temperature range.
Materials of Construction
Body: Acetal
Diaphragm: EPDM bonded
to steel ring
Contacts: Gold-plated silver
Springs: Plated phosphor bronze
Terminals: Plated copper or brass
Pressure Connection:
Spout for 1⁄8 ID tubing
Adjusting Screw:
Stainless steel or zinc-plated steel;
setting as shipped, 2 inH2O negligible
deadband
Media: Clean, dry, non-corrosive
gases only
Note: The pressure media entering through
port A are in direct contact with the electrical
contacts in the switch. The media entering
through port B are separated from the
electrical contacts by the diaphragm.
Weight: 9 g (0.3 oz)
TERMINAL
DIAPHRAGM
A
CONTACTS SET NORMALLY OPEN
PORT A: VACUUM NO
PORT B: PRESSURE NO
ADJUSTING SCREW
TERMINAL
B
Pressure Switching–
Normally Open Contacts
Connect the pressure source to inlet
port B, and set the adjusting screw to
the desired pressure setpoint. Turning
the screw clockwise narrows the gap
between contacts and decreases
the setpoint. Turning the screw
counterclockwise increases the gap,
thereby increasing the setpoint.
Pressure Switching–
Normally Closed Contacts
Connect the pressure source to port
A and monitor continuity across the
terminals. Slowly turn the adjusting
screw clockwise, narrowing the gap
AIR BLEED AVAILABLE
A
CONTACTS SET NORMALLY CLOSED
PORT A: PRESSURE NC
PORT B: VACUUM NC
between the contacts until the contacts
are closed. Apply the setpoint pressure,
which will open the contacts. Continue
to turn the adjusting screw clockwise
until the contacts make and break at
the desired setpoint.
Vacuum Switching: Repeat above
using port A for normally open contacts
and port B for normally closed contacts.
AS AN OPTION
B
To Order
MODEL NO. PRESSURE RANGE PROOF PRESSURE SWITCH RATING 250 Vac
PSW20A 0.4 to 15 inH2O 8 psig 750 mA (resistive)
PSW20B 1 to 20 inH2O 8 psig 1 A (resistive)
Ordering Example: PSW20A, sensitive differential pressure switch adjustable from 0.4 to 15 inH2O column.
Custom switches and pre-fixed setpoint at customer-specified value available, 50 piece minimum order.
Visit omega.com/psw21_psw22 for Pricing and Details
H-13
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