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  • Armstrong 4030 End Suction Base Mounted Pumps
  • Armstrong 4270 & 4270 Stock Motor Mounted Pumps
  • Armstrong 4280 Motor Mounted Pumps
  • Armstrong 4300 Vertical In-Line Pumps
  • Armstrong 4360 Vertical In-Line Pumps
  • Armstrong 4380 Vertical In-Line Pumps
  • Armstrong 4600 Horizontal Split-Case Pumps
  • Armstrong 4700 Vertical MultiStage Pumps
  • Armstrong Astro 2 Circulators
  • Armstrong Circulators
  • Armstrong E2 Circulators
  • Armstrong Expansion Tanks
  • Armstrong Flo-Trex Valves
  • Armstrong S&H 3-Piece Circulators
  • Armstrong Suction Guides
  • Bell & Gossett E-80
  • Bell & Gossett ecocirc® XL
  • Electric Motors
  • WEDA Submersible Drainage Pumps
  • wilo Stratos
  • Power Packs
  • Couplers
  • Bearing Assemblies
  • Impellers
  • Mechanical Seals
  • Circulator Pumps
  • Glycol Make Up Unit
  • Headers
  • Flange Sets
  • E-1510 Bell & Gossett
  • Submersible Pumps
  • Ball Bearings
  • Plumbing Supplies
  • Bell & Gossett
  • S.A. Armstrong
  • Water Transfer Pumps
  • Accessories

    • Shop by Brand

  • Armstrong
  • Bell & Gossett
  • Puffin
  • Zoeller
  • Barnes
  • John Crane
  • Eklind
  • View all Brands

    • Armstrong Expansion Tanks

    Armstrong Expansion Tanks

    An expansion tank absorbs the increase in water volume as a closed heating or cooling system warms up, keeping system pressure within limits. Without one, pressure rises until the relief valve opens – wasting water and treatment chemicals and drawing in fresh, oxygen-rich make-up water that causes corrosion.

    Armstrong offers diaphragm, bladder and plain steel expansion tanks for hydronic heating and cooling, plus potable water and domestic hot water tanks, in ASME and non-ASME construction.

    Which type do I need?

    • Diaphragm tanks (AX, AX-V, non-ASME) – a fixed diaphragm separates water and air; compact and economical.
    • Bladder tanks (L Series, WX-L) – water is held inside a replaceable butyl bladder, so it never touches the steel shell.
    • Potable and domestic hot water (WX-L, AST) – materials suitable for drinking water, NSF 61.
    • Plain steel tanks (AET) – traditional compression tanks, including high-temperature systems up to 450°F.
    • High pressure (AX-V 175/250 PSI, L Series High Pressure) – for tall buildings and high-pressure systems.

    Shop by series

    Warranty

    Covered by the Armstrong Fluid Technology manufacturer's warranty.

    Need help sizing?

    Send us the system volume, fill pressure, relief valve setting and operating temperatures and we'll recommend the right tank – call (416) 236-2338 or email sales@bramhambros.com.

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