Dwyer 3020MRS Photohelic Switch/Gauge 0 to 20 inch

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Dwyer 3020MRS Photohelic Switch/Gauge 0 to 20 inch

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Dwyer 3020MRS Photohelic Switch/Gauge 0 to 20 inch Specification

Thread
1/8 NPT Female

Sensor Type
Photohelic Differential Pressure Sensor

Seal Material
Silicone Rubber

Outer Size
Standard 4 (101.6 mm) Case

Grade
Industrial

Display
Analog Dial with Digital Switch Points

Bourdon Tube
Not Applicable (Uses Diaphragm Sensing Element)

Material
Die Cast Aluminum Case, Polycarbonate Window

Dial Material
Aluminum, White with Black Markings

Pointer Material
Black Anodized Aluminum

Processing Type
Pressure Sensing and Electrical Switching

Diameter
4 inch (101.6 mm) dial

Glass Size
Full View, Approx. 101 mm Diameter

Mount Type
Flush Panel or Surface Mount

Scale Range
0 to 20 inches of Water Column (in. w.c.)

Accuracy
2% of Full Scale

Accessories
Mounting Brackets, Installation Manual, Switch Cable Harness

Power Supply
None Required for Gauge; 120/240 VAC for Switch Operation

Response Time
Instantaneous, Mechanical

Mounting Orientation
Vertical Preferred

Electrical Rating
10A @ 120/240 VAC

Temperature Range
20F to 120F (-6.7C to 48.9C)

Process Connection Material
Brass

Protection Level
NEMA 2 Enclosure

Repeatability
1% of Full Scale

Switch Type
SPDT Snap Switch, 2 Setpoints

Weight
Approx. 1.5 lbs (0.68 kg)

Input Pressure Limits
-20 to 25 in. w.c.

Number of Switches
2 (Hi-Low Control)

Dwyer 3020MRS Photohelic Switch/Gauge 0 to 20 inch Trade Information

Payment Terms
Cash in Advance (CID), Cash on Delivery (COD), Cash Against Delivery (CAD), Cash Advance (CA)

Main Export Market(s)
Asia

Main Domestic Market
All India

About Dwyer 3020MRS Photohelic Switch/Gauge 0 to 20 inch

Dwyer 3020MRS Photohelic Switch/Gauge 0 to 20 inch

Series 3000MR/3000MRS Photohelic® Switch/Gage

Combines Differential Pressure Gage with Low/High Set-Points,Compact Size

Model	Description
3020MRS-20 inch	Pressure Switch/Gage,Range 0-20 inch, .50 minor divisions.

Includes

mounting ring, snap ring
18" cable assembly
(2) 3/16" tubing to 1/8" NPT adapters
(2) 1/8" NPT pipe plugs
(4) 6-32 x 1-1/4" RH machine screws (panel mounting)
(3) 6-32 x 5/16" RH machine screws (surface mounting)

he Series 3000MR Photohelic® Switch/Gage combine the functions of a precise, highly repeatable differential pressure switch with a large easy-to-read analog pressure gage employing the durable, time-proven Magnehelic® gage design. Switch setting is easy to adjust with large external knobs on the gage face. Gage reading is unaffected by switch operation - will indicate accurately even if power is interrupted. Solid state design now results in greatly reduced size and weight. Units can be flush mounted in 4-13/16" hole or surface mounted with hardware supplied. 3000MR models employ versatile electromechanical relays with gold over silver contacts - ideal for dry circuits.

Gage accuracy is ±2% of full scale and switch repeatability is ±1%. Switch deadband is one pointer width - less than 1% of full scale. Compatible with air and other non-combustible, non-corrosive gases, they can be used in systems with pressures to 25 psig.

Applications

Fan Control
Damper Control
Environmental Pollution Control

Approvals

CE Approval
GOST-R Certificate

Specification

Service	Air and non-combustible, compatible gases
Accuracy	±2% of FS at 70°F
Pressure Limits	-20" Hg to 25 psig
Temperature Limits	20 to 120°F
Process Connections	1/8 female NPT (duplicated side and back)
Size	4" dial face, 5" O.D. x 3-1/8"
Weight	1.8 lb
Switch Specifications
Switch Type	Each setpoint has 1 Form C relay (SPDT)
Relay Contacts	(resistive load) 1 Form C rated 1.0A @ 30 VDC, 0.3A @ 110 VDC or 0.5A @ 125 VAC. Gold over clad silver - suitable for dry circuits
Electrical Connections	18" cable assembly with 8 conductors
Power Requirements	24 VDC, regulated ±10%
Mounting Orientation	Diaphragm in vertical position
Set Point Adjustment	Adjustable knobs on face
Agency Approvals	CE

Dual-Function Pressure Monitoring and Control

The Dwyer 3020MRS seamlessly integrates both pressure measurement and electrical switching in a single device. Its two independent SPDT snap switches offer reliable Hi-Low setpoint control, giving users flexibility to automate processes or trigger alarms based on custom pressure thresholds. Suited for a range of fluids including steam, oil, and gas, the gauge ensures operational safety and efficiency in industrial settings.

Built for Durable Industrial Performance

Engineered with a die cast aluminum case, silicone rubber seals, and a matte black bezel, the Photohelic Switch/Gauge withstands tough operational demands. Its NEMA 2 enclosure provides drip-proof protection, while the full 4-inch polycarbonate dial ensures clear visibility. The easy-to-read analog display is coupled with digital switch point indication for confidence in monitoring and control tasks.

FAQ's of Dwyer 3020MRS Photohelic Switch/Gauge 0 to 20 inch:

Q: How does the Dwyer 3020MRS Photohelic Switch/Gauge function in pressure control applications?

A: The device uses a diaphragm-based sensor to measure differential pressure and activates one or both built-in SPDT snap switches when set pressure points are reached. This allows for automatic Hi-Low control, making it ideal for protecting systems or managing equipment based on specific pressure levels.

Q: What fluids can I safely monitor with this gauge?

A: The Dwyer 3020MRS is designed for steam, oil, and gas applications, making it versatile for various process control environments within industrial facilities.

Q: Where should the gauge be installed for optimal performance?

A: Vertical mounting is preferred to maintain measurement accuracy and proper mechanical operation. The switch/gauge can be flush panel or surface-mounted using supplied brackets, fitting easily into standard control setups.

Q: What is the process for setting up the photohelic switch points?

A: You can adjust the two setpoints directly on the front dial using the provided controls. Set the desired high and low pressure limits, ensuring both mechanical and electrical operations are tested for repeatability and functionality.

Q: When is power required for this device?

A: No external power is needed for passive gauge functionality; however, 120/240 VAC is necessary to operate the internal SPDT switches for alarm, control, or interlock functions.

Q: What are the benefits of using the Dwyer 3020MRS over a standard pressure gauge?

A: Beyond accurate analog readings (2% accuracy of full scale), the Dwyer 3020MRS provides instant electrical response and reliable switching for automated system control, reducing manual intervention and enhancing safety in dynamic industrial processes.

Q: How does the protection level benefit industrial usage?

A: The NEMA 2 rating ensures the device is safeguarded against drips and moderate environmental hazards, prolonging service life and reliability in typical indoor industrial environments.

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