20 and 25 SERIES PRESSURE SWICHGAGE®

2 and 2-1/2 in. (51 and 64 mm.) Dial

• Combination Indicating Gage and Limit Switch
• Critical Pressure Limit Switch Is Visible and Adjustable (Most Models)
• Switch Can Activate Alarms and/or Shutdown Equipment
• Exceeds SAE Standards

DESCRIPTION

The 20 Series (2 inch/51 mm. dial) and the 25 Series (2-1/2 inch/64 mm. dial) SWICHGAGE® models are diaphragm-actuated, pressure-indicating gages, with built-in electrical switches. These switches are used for tripping alarms and/or shutdown devices. Ranges are available from 0-15 PSI (103 kPa) [1.0 bar] thru 0-400 PSI (2.8 MPa) [28 bar]. The gage mechanism is enclosed in a steel case coated to resist corrosion. A poly-carbonate, break-resistant lens and a polished, stainless steel bezel help protect this rugged, built-to-last instrument. Accuracy and protection from moderate overpressure is assured by a unique, unitized diaphragm chamber. A built-in pulsation dampener helps eliminate pointer flutter and is removable for cleaning. For models 20P and 25P, the gage pointer acts as a pressure indicator and as one switch pole which completes a circuit when it touches the adjustable limit contact. Contacts are grounded through the SWICHGAGE® case and have self-cleaning motion to ensure electrical continuity. Models 20PE and 25PE have internal snap-acting SPDT switches. Gage-only models, without the switches (MURPHYGAGE®) are also available.

Applications

The SWICHGAGE® was specifically designed to protect engines/equipment in Oil Field, Marine, Irrigation, Construction and Trucking applications to monitor Engine Lube Pressure, Water Pump Pressure, Hydraulic Pressure, Air Pressure, etc.

ORDERING DETAILS

Description

Specifications

Dial: White on black, dual scale; U.S.A. standard scale is psi/kPa; U.K. standard scale is psi/bar; others available

Case: Plated steel; mounting clamp included (except for direct mount models).

Bezel: Polished stainless steel, standard; others are available (see How to Order).

Lens: Polycarbonate, high-impact.

Oil: Silicon Oil.

Temperature Range: Ambient: -40°F (-40°C) thru 150°F (66°C). Process: -40°F (-40°C) thru 250°F (121°C).

Process Connection: 1/8-27 NPTM brass.

Sensing Element: Beryllium copper diaphragm.

Gage Accuracy (% of Full Scale):

Range

Lower 1/4

Middle 1/2

Upper 1/4

300 psi (20 Bar)

±3%

±2%

±3%

400 psi (28 Bar)

±3%

±3%

±5%

Maximum Pressure: See Pressure Ranges and Factory Settings table on page 2.

Adjustable Limit Contact (20P and 25P):SPST contact; pilot- duty only, 2 A @ 30 VAC/DC; Normally Close (NC) when the low limit is met. Normally Open (NO) when pointer is in normal operating range. Contacts are gold flashed silver.Limit Contact Adjustment: by a 1/16 in. hex wrench through 100% of the scale.Limit Contact Wire Leads: 18 AWG (1.0 mm2) x 12 in. (305 mm.).

Snap-Switch Rating (20PE and 25PE): SPDT, 3 A@ 30 VDC inductive; 4 A @ 125 VAC inductive.Snap-Switch Wire Leads: 20 AWG (0.75 mm2) x 2 in. (305 mm).

Unit Weight: 20 Series: 8 oz. (0.23 kg). 25 Series Models: 11 oz. (0.31 kg).

Unit Dimensions: 20 Series: 3 x 3 x 3 in. (76 x 76 x 76 mm.). 25 Series Models: 4-3/4 x 4-3/4 x 2-3/4 in. (121 x 121 x 70 mm.).

Base Models

20P and 25P Series SWICHGAGE®
The gage pointer makes with an adjustable contact to complete a pilot-duty circuit.

20PE and 25PE SWICHGAGE®
20PE (was 20EO) and 25PE (was 25EO).Features internal snap-acting SPDT switches, instead of the single pole/pointer contacts. When the switch closes on falling pressure, it becomes Set, as pressure rises the switch Resets.

20PABS and 25PABS SWICHGAGE®
Same as 20P and 25P with internal SPDT snap-switch for pre-alarm.

20P7 and 25P7 Lockout SWICHGAGE®
Same as 20P and 25P Series. They also include a front, semi-automatic lockout for startup override. This built-in device holds the pointer away from the contact on startup. When pressure exceeds the set point, the lockout is automatically disengaged

20PG and 25PG MURPHYGAGE®
Gage without contact(s).

Warranty

A two-year limited warranty on materials and workmanship is given with this Murphy product. Details are available on request and are packed with each unit.

**Products covered by this bulletin comply with EMC Council directive 89/336/EEC regarding electromagnetic compatibility except as noted.

Dimensions

 20-series 25-series

Pressure Ranges and Factory Settings

NOTES

1. Values in () are mathematical conversions from psi to kPa/MPa–they do not reflect actual second scale range. U.S.A. standard scale is psi/kPa;U.K. standard scale is psi/bar-exact set-point shown. Consult factory for other scales.
2. For models A20PE and A25PE; the switch trip point cannot be set at either the low or high extreme of the scale. The trip point must allow for the reset differential.
3. For adjustable switch models, the trip point is adjustable only over the lower half of the scale.

Ranges Available

Maximum Pressure

Standard Settings

High Settings*

A20PABS and A25PABS Settings Low Alarm†

psi

(kPa)

[bar]

psi

(kPa)

[bar]

psi

(kPa) [bar]

psi

(kPa)

[bar]

psi

(kPa) [bar]

0-15

(103)

[1.0]

30 psi (207)

3

(21)

[0.2]

12

(83) [0.8]

3

(21)

[0.2]

6

(41)

[0.3]

0-30

(207)

[2.0]

60 psi (413)

7

(48)

[0.4]

24

(165) [1.6]

7

(48)

[0.4]

10

(69)

[0.6]

0-50

(345)

[3.5]

100 psi (690)

10

(69)

[0.8]

40

(276) [2.8]

10

(69)

[0.8]

13

(90)

[1.0]

0-75

(517)

[5.0]

150 psi (1.0mpa)

15

(103)

[1.0]

60

(414) [4.0]

15

(103)

[1.0]

18

(124)

[1.5]

0-100

(690)

[7.0]

200 psi (1.4mpa)

20

(138)

[1.5]

80

(552) [5.5]

20

(138)

[1.0]

23

(159)

[1.5]

0-150

(1.0 MPa)

[10]

300 psi (2.1 mpa)

30

(207)

[2.0]

120

(827) [8.0]

30

(207)

[1.5]

33

(228)

[2.0]

0-200

(1.4 MPa)

[14]

400 psi (2.8 mpa)

50

(345)

[3.0]

150

(1 MPa) [10]

50

(345)

[3.0]

53

(365)

[4.0]

0-300

(2.1 MPa)

[20]

500 psi (3.4 mpa)

75

(517)

[5.0]

225

(1.6 MPa) [15]

75

(517)

[5.0]

78

(538)

[5.0]

0-400

(2.8 MPa)

[28]

500 psi (3.4 mpa)

150

(1.0 MPa)

[7.0]

300

(2.1 MPa) [20]

75

(517)

[5.0]

150

(1 MPa)

[10]

**Low settings for Hi/Lo option same as standard settings. Hi/Lo option available for A20P and A25P models only.
†SPDT Snap-switch is the alarm switch.

Features

A. Process Connection and Port: Machined from brass bar stock. Together with the diaphragm forms the diaphragm chamber.

B. Diaphragm (not shown): Beryllium copper die formed and heat treated to very close physical and

metallurgical specifications.

C. Pulsation Dampener: Designed to minimize undesirable pointer chatter. It is removable for cleaning.

D. Dial: White letters on a black background, dual scale; others available on request–see How to Order.

E. Case: Polycarbonate/glass filled, corrosion resistant; mounting clamp included.

F. Bezel: Polished stainless steel standard, black bezel also available.

G. Lens: Made of high-impact resistant treated polycarbonate.

H. Pointer: Tempered nickel silver for continuity and corrosion resistance—mounted on a machined brass post. Red tip.

I. Limit Contact: SPST contact; N.C. when low limit is met. N.O. when pointer operates above limit.

J. Limit Contact Adjustment: by 1/16 in. hex type wrench thru 100% of the scale. Easy adjustment knob available.

K. Electrical Connections: Number 4 screw terminals for A20 Series; and number 6 screw terminals for A25 Series models.

dia4

None.