- Official UK and Ireland channel partner
- UK technical support available
- Model selection and configuration support
Dwyer Series 3000MR/MRS Photohelic Differential Pressure Switch Gauge
Combine local differential-pressure indication with two adjustable setpoints for alarm or external control circuits.
Key highlights
- Indication: 4-inch analogue differential-pressure gauge
- Setpoints: Two front-adjustable low and high limits
- Outputs: MR relay or MRS solid-state AC switching
- Ranges: Imperial and metric scales available
- Mounting: Flush-panel or surface installation
The Dwyer Series 3000MR and 3000MRS Photohelic family combines a differential-pressure gauge with two adjustable switching setpoints. The 4-inch analogue dial provides local indication, while front-mounted low and high setpoint controls support alarm or external on/off control duties.
Mechanical gauge indication remains available if the electrical supply is interrupted. The switching section requires a regulated 24 VDC supply, so indication and powered switching should be treated as distinct functions when specifying the instrument.
The main family choice is the output technology. Series 3000MR provides two electromechanical Form C relays with SPDT contacts for compatible resistive and dry-circuit duties. Series 3000MRS provides two normally open solid-state outputs for high-cycle AC switching applications within the published voltage and current limits.
Pressure ranges extend from 0-0.25 to 0-100 in w.c., with selected Pa, kPa, mm w.c. and cm w.c. scales. Most ranges are rated to ±2% of full scale, with reduced accuracy on the lowest ranges. Standard, medium-pressure and high-pressure constructions are available, alongside environmental, bezel, calibration and tamper-resistant options.
Typical duties include filter monitoring, HVAC systems, clean rooms, pneumatic conveying, fan or blower monitoring and building-pressure alarm or on/off control circuits. Selection should account for pressure range and units, MR or MRS output type, switched load, system pressure, temperature, mounting and any enclosure or bezel option.
Key Features
- Combined instrument: View differential pressure locally and use separate low and high setpoints for alarm or external on/off control circuits
- Independent indication: Mechanical gauge reading is unaffected by switch operation and continues during electrical power loss
- Front adjustment: Set both switching thresholds from accessible controls on the gauge face
- 3000MR outputs: Two Form C electromechanical relays provide SPDT contacts for compatible resistive and dry-circuit loads
- 3000MRS outputs: Two SPST normally open solid-state outputs support high-cycle AC switching duties
- Range choice: Select imperial or metric pressure scales to suit the application
- Mounting flexibility: Install flush in a panel or on a surface using the supplied hardware
- Application options: Specify medium/high-pressure, low-temperature, weatherproof, stainless-steel bezel, tamper-proof or calibration options where required
Specifications
| Measurement and Indication | |
| Instrument function | Analogue differential-pressure indication with two adjustable switching setpoints |
| Service | Air and other compatible, non-combustible gases |
| Inch water ranges | 0-0.25, 0-0.5, 0-1, 0-2, 0-3, 0-5, 0-10, 0-15, 0-20, 0-30, 0-50 or 0-100 in w.c. |
| Metric ranges | 0-60, 0-125, 0-250 or 0-500 Pa; 0-1, 0-3 or 0-4 kPa; 0-6, 0-10, 0-25, 0-50 or 0-100 mm w.c.; 0-20 cm w.c. |
| Gauge accuracy | ±2% of full scale for most ranges; ±3% for -0, -125PA and -10MM ranges; ±4% for -00, -60PA and -6MM ranges |
| Switch repeatability | ±1% of full scale |
| Switch deadband | One pointer width; less than 1% of full scale |
| Dial size | 4-inch (101.6 mm) face |
| Power-loss behaviour | Gauge continues to indicate pressure; powered switching outputs are unavailable without supply power |
| Switching and Electrical | |
| Setpoints | Two independently adjustable low and high limits; controls on gauge face |
| 3000MR switch type | One Form C electromechanical relay per setpoint; two SPDT relay outputs |
| 3000MR contact ratings | Resistive load: 1.0 A at 30 VDC, 0.3 A at 110 VDC or 0.5 A at 125 VAC; gold over clad silver contacts |
| 3000MRS switch type | One solid-state relay per setpoint; two SPST normally open outputs |
| 3000MRS switching voltage | 20-280 VAC, 47-63 Hz |
| 3000MRS switching current | 1.0 A AC maximum; 0.01 mA AC minimum |
| Power requirement | 24 VDC regulated, ±10%, for both MR and MRS |
| Electrical connection | 18-inch (46 cm) cable assembly; eight conductors for MR and six for MRS; optional lengths to 100 ft (30.5 m) |
| Media, Pressure and Environment | |
| Wetted materials | Confirm with DwyerOmega for the selected medium |
| Standard pressure limit | -20 inHg to 25 psig (-0.677 to 1.72 bar) |
| Elevated-pressure options | -MP: 35 psig (2.41 bar) maximum; -HP: 80 psig (5.52 bar) maximum |
| Standard temperature limits | 20 to 120°F (-6.7 to 48.9°C) |
| Low-temperature option | -LT construction for service below the standard 20°F (-6.7°C) lower limit; confirm the required minimum temperature |
| Pressure connections | 1/8-inch female NPT high and low ports, duplicated at side and back |
| Mechanical and Mounting | |
| Mounting | Flush-panel or surface mounting with supplied hardware |
| Mounting orientation | Diaphragm vertical for standard calibration; confirm other orientations when ordering |
| Standard dimensions | 5-inch (127 mm) outside diameter x 3-1/8-inch (79.4 mm) depth |
| Stainless-steel bezel dimensions | 4-3/4-inch (120.7 mm) outside diameter x 2-21/32-inch (67.5 mm) depth |
| Weight | Approximately 816 g |
| Standard supplied hardware | Mounting ring, snap ring, 18-inch cable assembly, two tubing-to-NPT adapters, two pipe plugs and panel/surface mounting screws |
| Options | |
| Pressure constructions | -MP medium-pressure or -HP high-pressure |
| Environmental and access options | -LT low-temperature, -WP weatherproof housing and -TAMP tamper-proof setpoint knobs |
| Bezel and calibration options | -SS 304 brushed stainless-steel bezel and -NIST traceable calibration certificate |
| Compliance | |
| Compliance | CE |
Support
Able Instruments are an official UK and Ireland channel partner for DwyerOmega, providing application advice, configuration support and quotation assistance for the Series 3000MR and 3000MRS Photohelic family.
- Model selection: Support matching the pressure range, units, MR or MRS switching and pressure construction
- Option compatibility: Checks for switched load, cable, bezel, weatherproof, low-temperature, tamper-proof and calibration requirements
- Installation support: Advice on pressure connections, vertical orientation, panel or surface mounting and electrical interfacing
- Documentation support: Help with the datasheet, family-specific operating manual, wiring information and replacement requirements
Accessories
- A-370 steel mounting bracket for a surface-mounted flush-mount arrangement
- A-600 R/C snubber for compatible inductive switched loads