Magnehelic PrincipleThe Photohelic and Capsu-Photohelic models combine our most precise pressure switch with our time- proven Magnehelic design. The knob controls adjust the set points. Two phototransistor actuated, DPDT relays are included for low/high limit control.
Typical ApplicationsTo measure liquid levelUse a Photohelic®, Magnehelic®, or Minihelic® gage in conjunction with aDwyer flowmeter with constant differential pressure regulator as show.Flowmeter provides constant rate of purge air to dip tube. Changes in liquidlevel affect head, causing static pressure changes inside tube. Thesechanges are sensed by the gage. This same kind of setup will also detectspecific gravity changes in the liquid if level is kept constant. Using a DwyerPhotohelic® pressure switch/gage instead of the Magnehelic® permits bothmeasuring and controlling liquid level plus easily changing the level controlsettings.To control pressure in air-inflated buildingsPhotohelic® switch/gage senses over-pressure that may extend building, orloss of pressure that may cause collapse, and controls the blower tomaintain correct pressure. Gage is easily reset to conserve power - orprovide extra pressure to resist strong winds.To control material weightOn paper making or textile machinery, a Photohelic® switch/gagecontrols weight of material gathered by sensing pressure changescaused by changes in permeability and thickness of the material.
Typical ApplicationsMonitor air conditioning systemsAdjustments in air flow due to seasonal changes may require resetting thecontrol points on a regular basis. The Photohelic® units ability to monitorpressures through the gage portion also permits accumulation of operatingdata. This is useful in adjusting operation of variable pressure and volumesystems and in making system changes when necessary.For life support or kidney machinesPhotohelic® switch/gage controls pressure on circulating system ofmachine and alarms in event of too high or low pressure.
Specifications Series A3000/3000 Photohelic Differential Pressure Switch/Gages• Media: Air and non-combustible, compatible gases• Pressure Limits: -20” Hg to 25 psig• Temperature Limits: 20o to 120o F• Connections: 1/8” female NPT• Accuracy: +/- 2% full scale (3% on -0, 4% on -00 ranges)• Wetted Parts: Aluminum housing with silicone diaphragm• Power Supply: 120 VAC• Special Note: For non UL/CSA listed Photohelic models delete the “A” prefix from the model number.
Design & Construction Features 1. Bezel and front cover (with set point knobs and zero adjustment screw) removed to expose Photohelic set point 1 mechanism. Cover is clear polycarbonate plastic.2 2. Gage pointer and light shutter are mounted on helix and balancing counterweight. Shutter passes through slot in optical3 limit switch to expose phototransistors to integral infrared light source or mask them depending on applied pressure 3. Light shield effectively protects phototransistors from strong4 outside light sources yet allows free pointer movement. It also gives interior a clean "finished" look. 4. Semi-Flexible drive shaft connects to set point knobs. 5 5. Optical limit switches are used for reliability and long service life. Attached directly to set pointers, they are individually aligned to assure precise switching accuracy. 6 6. Zero adjustment screw connects to screw in cover to adjust zero pressure reading.
Design & Construction Features 7. Plastic enclosure protects electronic components and 7 electrical connections. 8 8. Polycarbonate connection or terminal board is self- 9 extinguishing(A3000 only). 9. Glass epoxy printed circuit boards for durability and permanence. 10 10. Load relays are DPDT with latching feature for maximum application versatility. 11. Electronics are designed to operate on 50/60 Hz, 120 volt current with 10% over or under voltage. Special units for other 11 voltages are available. 12. Switch set pointers show switch settings at all times. 12 13. Spring loaded friction clutch prevents operator damage of set point mechanism.13
Options• -24VAC: 24 VAC Relay Pack • -M: Mirror Overlay• -240VAC: 220/240 Relay Pack • -MP: Medium Pressure (35 psi)• -EXPL: Explosion Proof Housing • -NIST: NIST Certificate• -G: Green Overlay • -RMR: Remote Mounted Relay (5ft)• -HC: Horizontal Calibration • -SRH: Single Right Hi Latching• -HJ: Helix Jump Preventer • -SRL: Single Right Lo Latching• -HP: High Pressure (80 psi) • -R: Red Overlay• -OLS: Less Relay • -TAMP: Tamperproof Knobs• -LT: Low Temperature • -WP: Weather Proof HousingAccessories: A-601, manual reset switch
Special Scales Like the Magnehelic, Dwyer also offers special scales on the Photohelic. Any equivalent rangewithin the gage’s capabilities can bemade. These scales include ranges in Pa, KPa, mm WC, and inches Hg or flow ranges in FPM, CFM, GPM, CFH, M3H, and PPH.
Specifications Series 43000 Capsu-Photohelic Differential Pressure Switch/Gages• Media: Compatible gases and liquids• Pressure Limits: -20” Hg to 500 psig• Temperature Limits: 20o to 120o F• Connections: 1/4” female NPT• Accuracy: +/- 3% full scale (2% on 43000S models, 4% on 43215, 43220, 43500)• Wetted Parts: Aluminum housing with silicone diaphragm, optional brass housing• Power Supply: 120 VAC
Options• -24VAC: 24 VAC Relay Pack • -M: Mirror Overlay• -240VAC: 220/240 Relay Pack • -NIST: NIST Certificate• -EXPL: Explosion Proof Housing • -RMR: Remote Mounted Relay (5ft)• -G: Green Overlay • -SRH: Single Right Hi Latching• -HC: Horizontal Calibration • -SRL: Single Right Lo Latching• -OLS: Less Relay • -R: Red Overlay• -LT: Low Temperature • -TAMP: Tamperproof Knobs • -WP: Weather Proof Housing
Special ScalesDwyer also offers special scales on the Capsu-Photohelic. Any equivalent range within the gage’s capabilities can be made. These scales include ranges in Pa, KPa, mm WC, and inches Hg or flow ranges in FPM, CFM, GPM, CFH, M3H, and PPH.
Specifications Series 3000MR/MRS Photohelic Differential Pressure Switch/Gages• Media: Air and non-combustible, compatible gases• Pressure Limits: -20” Hg to 25 psig• Temperature Limits: 20o to 120o F• Connections: 1/8” female NPT• Accuracy: +/- 2% full scale (3% on -0, 4% on -00 ranges)• Wetted Parts: Aluminum housing with silicone diaphragm• Power Supply: 24 VDC
Differences from standard modelOnly 2 SPDT contacts on MR model.The MRS has SPST solid state outputs. 3000MR/MRS has cable for wiring instead of screw terminal relay pack.
Specifications Series MP Mini-Photohelic Differential Pressure Switch/Gages• Media: Air and non-combustible, compatible gases• Pressure Limits: 30 psig• Temperature Limits: 20o to 120o F• Connections: Barbed for 3/16” tubing• Accuracy: +/- 5% full scale• Wetted Parts: Nylon housing with silicone diaphragm• Power Supply: 24 VDC or 24 VAC
QuestionsTo order a free catalog or for more information contact; Dwyer Instruments, Inc., P.O. Box 373, Michigan City, IN., 46361 Telephone: (800) 872-9141 or (219) 879-8000 Fax: (219) 872-9057 Internet address: www.dwyer-inst.com E-mail: firstname.lastname@example.org
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