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Design Envelope 4302 dualArm Pumps

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Design Envelope 4302 isometric view
Design Envelope 4302 Front

  • Summary
  • Applications

    HVAC system pumping; general purpose pumping; industrial/process pumping (water or glycol based) 
    Armstrong Design Envelope Pumps with integrated controllers are OSHPD pre-approved!

  • Description

    Pipe-mounted 2-pump unit with integrated intelligent controls for space-saving installation, superior energy performance, and full redundancy or parallel-pumping operation. Saves up to 75% in energy over comparable traditional constant speed or variable frequency operated pump installations.

  • Materials
    • Cast iron or ductile iron casing
    • Cast iron or bronze impeller
    • Sintered silicon carbide mechanical seal
  • Configuration

    On-board Intelligent Variable Speed controls with Sensorless or Parallel Sensorless control. Controls enclosure UL type 12 or UL type 4X (outdoor applications). Available with NEMA premium motors. Outside balanced or inside single spring mechanical seal

  • Performance range

    Up to 1250 USgpm flow and 250 ft head (80 L/s, 76 m) 

  • Temperature

    250°F (121°C)

  • Power Range

    0.33 hp to 75 hp (0.25 kW to 55 kW) 

  • Size

    1" to 8” (25 mm to 200 mm) 

Lowest installed cost

  • Vertical In-line design eliminates the need inertia bases, housekeeping pads, and flex connectors and reduces piping requirements
  • 2-pump casing for reduced footprint
  • Integrated, intelligent controls eliminate the need for procurement, installation (incl. wiring), calibration and upkeep of differential pressure sensor
  • Superior energy performance qualifies for significant cost recovery under utility and government rebate programs
  • Design Envelope selections frequently recommend a smaller motor and/or pump which reduces installed cost

Pump Models Designed and Engineered for Outdoor Operation

Controls enclosure rated for UL type 4x. Equipped with overhead weather shield to prevent icing in cold weather or overheating in direct sunlight.

Lowest operating cost

  • Integrated intelligent controls – combined with perfect component match-up and tuning – for up to 75% in energy savings over traditional constant speed and variable frequency operated pumping installations
  • Available with Parallel Sensorless control (patent pending) to provide best-efficiency staging of both pumps for additional energy savings
  • Shorter pipe runs reduce system friction 
Design Envelope

Lowest installed cost. Lowest operating cost.


Lowest energy consumption and carbon emissions

  • Integrated intelligent controls – combined with perfect component match-up and tuning – for up to 75% lower energy consumption and carbon (greenhouse gas) emissions
  • Available with Parallel Sensorless control (patent pending) for best-efficiency staging of both pumps leading to additional energy savings



Lowest project and operating risk

  • Integrated intelligent controls – combined with perfect component match-up and tuning – for fast and easy commissioning
  • Integrated intelligent controls for reduced radio frequency interference/ improved electromagnetic compatibility
  • Single source-responsibility for optimum design and field support
  • DualArm pumps are designed for full redundancy in case of emergency or routine servicing (each pump can be individually isolated from the system with the second pump still operating)
  • ETL Listed - conforms to UL STD 778
  • Certified to CSA STD C22.2 NO.108
  • OSHPD Special Seismic Certification Pre-approval (OSP) No OSP-0422-10

Case study: Cooling system transplant

Methodist Medical Center Reduced cooling costs by $107,000 in just 5 months.

Learn more


U.S.A. Utility Energy Rebate Info.

360 Service and Support

Design Envelope IVS Pumps with Cloud Based Active Performance Management – solution outline

Design Envelope single-phase power supplement

Variable frequency drives and the use of bypasses - fact sheet

Armstrong Design Envelope - FAQs

Fused Disconnects for use with Design Envelope Pumps - white paper

Design Envelope pump vs. a variable speed drive on the wall - white paper

E-Coating - white paper

Working Clearances of Design Envelope Pump Controls - WhitePaper

Submittals (with touch screen)


Submittals (single-phase)




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