Photohelic 3000 vs Magnehelic 2000: Differences & Selection Guide
Posted on: 23/07/2026
1. The Core Difference Lies in One Capability
The fundamental distinction between these two product series is the capability for AUTOMATIC SETPOINT SWITCHING / CONTROL:
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Dwyer Magnehelic Series 2000: INDICATION ONLY. Purely mechanical dial display for local operator inspection and manual recording.
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Dwyer Photohelic Series 3000MR / 3000MRS: INDICATION + SETPOINT SWITCHING CONTROL. When actual pressure exceeds or falls below preset setpoints, it automatically actuates relay contacts to trigger alarms, buzzers, or send control signals to start/stop fans or dust collector pulse valves.
2. Detailed Comparison: Magnehelic 2000 vs Photohelic 3000
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Criteria
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Magnehelic Series 2000
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Photohelic Series 3000MR/3000MRS
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Main Function
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Local pressure indication only
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Continuous pressure indication+ Dual setpoint control output
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Setpoint Adjustment
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None
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Integrated dual setpoint indicators (High/Low) easily adjustable via knobs
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Power Supply Required
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No power required (Purelymechanical)
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Power supply required (24VDC/VAC or 120/240VAC for relay circuit)
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Output Contacts
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None
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2 DPDT Relays (3000MR) or Solid State Relays (3000MRS)
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Typical Applications
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AHU filter monitoring, basic cleanroom pressure check
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Automated dust collector pulsing, alarm sirens, emergency fan control
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Installation & Wiring
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Very simple (Pneumatic tubin only)
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Requires pneumatic tubing + power and control wiring
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Investment Cost
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Lower, budget-friendly
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Higher (due to integrated optical sensors and control electronics)
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3. Technical Highlights of Photohelic Series 3000MR / 3000MRS
The Photohelic 3000 utilizes non-contact phototransistor technology, allowing setpoint switching without any mechanical friction or interference with the gauge pointer.
Key Technical Advantages:
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Frictionless Optical Sensing: Ensures continuous, accurate gauge readings without mechanical wear or contact sticking.
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Dual Independent Setpoints (High/Low): Enables safe differential pressure band setting (e.g.,alert when pressure drops below 50 Pa or exceeds 300 Pa).
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Flexible Reset Modes: Supports automatic reset or manual latching reset depending on process safety requirements.
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3000MR vs 3000MRS Options: 3000MR features robust electro-mechanical DPDT relays; 3000MRS utilizes Solid State Relays (SSR) for high-requency switching and infinite mechanical lifespan.
4. Special Case: Hazardous Areas & Explosion-Proof Requirements (ATEX/IECEx)
In industrial environments with high explosion risks such as chemical processing plants, spray painting booths, oil refineries, pharmaceutical powder handling, or flour/dust silos, standard electrical devices pose severe ignition risks.
In these environments, certified explosion-proof instruments compliant with ATEX / IECEx standards are mandatory. DLK provides genuine explosion-proof models:
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Photohelic ATEX Series 3000MR/MRS: Enclosed in heavy-duty flameproof aluminum housings, protecting internal electronics and relays in Zone 1, Zone 2, Zone 21, and Zone 22 environments.
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ATEX A3000 Differential Pressure Switch/Gauge: Dedicated explosion-proof combination gauge-switch for hazardous HVAC and exhaust treatment systems.
5. Which One Should You Choose?
✅CHOOSE MAGNEHELIC SERIES 2000 IF:
- You only need manual visual pressure checks during routine maintenance.
- No power line is available at the measurement location.
- You require a highly cost-effective, long-lasting mechanical solution with no risk of circuit failure.
✅ CHOOSE PHOTOHELIC SERIES 3000MR/3000MRS IF:
- Process automation is required (e.g., auto-triggering alarm beacons when filters clog).
- Automatic pulse-jet cleaning control is needed in dust collector systems.
- Emergency fan shutoff or damper actuation is required upon cleanroom overpressure.
Explore genuine products available at DLK: