Dwyer Series A3000 Photohelic® Pressure Switch/Gage

Product Description

3-in-1 Indicating Gage, Lo-limit and Hi-limit Control

Photohelic® Switch/Gages function as versatile, highly repeatable pressure switches combined with a precise pressure gage employing the time-proven Magnehelic® gage design. The Photohelic® switch/gage measures and controls positive, negative or differential pressures of air and compatible gases. Standard models are rated to 25 psig (1.7 bar) with options to 35 (2.4) or 80 (5.5 bar) psig. Single pressure 36000S models measure to 6000 psig (413 bar) with a 9000 psig (620 bar) rating. Two phototransistor actuated, DPDT relays are included for low/high limit control. Easy to adjust set point indicators are controlled by knobs located on the gage face. Individual set point deadband is one pointer width – less than 1% of full scale. Set points can be interlocked to provide variable deadband – ideal for control of fans, dampers, etc. Gage reading is continuous and unaffected by switch operation, even during loss of electrical power. Choose from full scale pressure ranges from a low 0-.25″ (0-6 mm) w.c. up to 30 psi (21 bar); single positive pressure to 6000 psig (413 bar).

Photohelic Sensing – How It Works
In typical applications, these Dwyer switch/gages control between high and low pressure set points. When pressure changes, reaching either set point pressure, the infrared light to the limiting phototransistor is cut off by the helix-driven light shutter. The resulting phototransistor signal is electronically amplified to actuate its DPDT slave relay and switching occurs. Dead band between make and break is 1% of full scale or less – just enough to assure positive, chatter-free operation.

Relay-Transformer Features
A plastic housing protects all electronic components. Solid-state and integrated circuit electronics are on glass-epoxy printed circuit boards and self-extinguishing terminal boards.

Please see SERIES AT3A3000 for ATEX approved.

Product Applications

• Air Conditioner Systems
• Clean Rooms
• Fume Exhaust Systems

Models

Specifications

GAGE SPECIFICATIONS

Service:

Air and non-combustible, compatible gases.

Wetted Materials:

Consult Factory.

Accuracy:

±2% of FS at 70°F (21.1°C). ±3% on -0 and ±4% on -00 models.

Pressure Limits:

-20″ Hg. to 25 psig (-0.677 to 1.72 bar). MP option; 35 psig
(2.41 bar), HP option; 80 psig (5.52 bar).

Temperature Limits:

20 to 120°F. (-6.67 to 48.9°C). Low temperature option available.

Process Connections:

1/8″ female NPT.

Size:

4″ (101.6 mm) dial face, 5″ (127 mm) O.D. x 8-1/4″ (209.55 mm).

Weight:

4 lb (1.81 kg).

SWITCH SPECIFICATIONS

Switch Type:

Each setpoint has 2 Form C relays (DPDT).

Repeatability:

±1% of FS.

Electrical Rating:

10A @ 28 VDC, 10A @ 120, 240 VAC.

Electrical Connections:

Screw terminals. Use 167°F (75°C) copper
conductors only.

Power Requirements:

120 VAC, 50/60 Hz; 240 VAC & 24 VAC power
optional.

Mounting Orientation:

Diaphragm in vertical position. Consult factory for
other position orientations.

Set Point Adjustment:

Adjustable knobs on face.

Agency Approvals:

CE, CSA, UL. Optional-EXPL explosion-proof
enclosure does not possess any agency approvals.

Features

• Bezel and front cover (with set point knobs and zero adjustment
  screw) removed to expose Photohelic® switch/gage set point mechanism.Cover
  is clear polycarbonate plastic.
• Gage pointer and light shutter are mounted on helix and balancing
  counterweight. Shutter passes through slot in optical limit switch
  to expose phototransistors to integral infrared light source or mask
  them depending on applied pressure.
• Light shield effectively protects phototransistors from strong
  outside light sources yet allows free pointer movement. It also gives
  interior a clean “finished” look.
• 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.
• Semi-Flexible drive shaft connects to set point knobs.
• Zero adjustment screw connects to screw in cover to adjust
  zero pressure reading.
• Plastic enclosure protects electronic components and electrical
  connections.
• Polycarbonate connection or terminal board is self-extinguishing.
• Glass epoxy printed circuit boards for durability and permanence.
• Load relays are DPDT with latching feature for maximum application
  versatility.
• Electronics are designed to operate on 50/60 Hz, 120 volt
  current with 10% over or under voltage. Special units for other voltages
  are available.
• Switch set pointers show switch settings at all times.
• Spring loaded friction clutch prevents operator damage of
  set point mechanism.
• 3-in-1 instrument allows the reduction of several instruments with one product, saving inventory, installation time and money.
• Patented design and 1% full scale deadband provides quick response to pressure changes means no delay in switching and chatter-free operation.
• A wide range of models that can meet pressure measurement specifications from low to very high.

Options

• -SR Single contact, right set point, for actuation on increasing
  or decreasing pressure.
• -OLS OEM Model, less relay and transformer components and housing
  but including infared diodes and phototransistor(s), light shutter and
  set pointer(s). For single or double contact.
• -RMR Remote-Mounted Relay, relay pack may be mounted remotely
  from gage. Standard length is 5 ft. For other lengths, specify cable
  length required.
• -TAMP Tamper-proof knobs, low temperature option, special scales, voltages
  and other features and modifications are available.
• Special Housings available include Weatherproof (NEMA 4) and Explosion-proof
  (NEMA 7 & 9; NEC Cl I, Gr C&D; Cl II, Gr E, F&G; Cl III). Contact
  Customer Service for detailed dimension drawings.
• Scale No. 3401 Square Root Specify Range.
• Scale No. 3402 Blank Scale Specify Range.
• High & Low Latching Circuits. Dwyer Photohelic® switch/gages can be wired for high-latching, low-latching or
  combination high-low latching circuits. That is, the equipment will
  hold in these respective positions once activated and until manually reset.
  This can
  be particularly useful for alarm and signal applications where control is accomplished
  by another Photohelic® switch/gage or other means. Complete
  wiring and operational instructions are included. Where manual reset is required
  a dry
  circuit push button such as Dwyer
  Part A-601 should be used.

Literature

Manuals

• Instruction Manual (A3000)
• Instruction Manual (3000)

Catalog Pages

Series A3000 Catalog Page

Approvals

• UL Approval – Canada
• CSA Certified – Industrial Control Equipment
• CSA Certified – Switches
• UL Approval – US
• CE
• GOST-R Certificate

Drawings

• dwg
• pdf
• 3D Drawing – A3000
• 3D Drawing – A3000-WP

Accessories

	Model Number	Description
	A-601	Manual reset switch.
	A-298	Flat aluminum bracket for flush mounting Photohelic® & Capsuhelic® gages, 603A, 605, and 3000MR.

Model Chart

Apps

Air Velocity and Flow Calculator