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Amac Amac

Polywater® FST™ MINI Duct Sealant

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A Foam Duct-Sealing System
for Conduit Sizes 3/4″ up to 2″

  • Strong – Holds up to 22ft/7m of water head pressure.
  • Compatible – PVC, rigid steel, EMT, fiberglass, and all other conduits.
  • Easy – Two-part foam is mixed in nozzle as it is injected into duct.
  • Quick – Foam expands and cures quickly even when water is present.
  • Multi-Use – Packages are resealable. 

Polywater® FST MINI is an expanding, quick-setting, “closed-cell foam”, which is injected into a conduit to provide a watertight seal. The seal is superior to pliable duct putties and “open-cell” aerosol canned foams. Polywater® FST MINI comes in a kit that contains side-by-side cartridges filled with the two-part foam base. The two resins are mixed in equal parts as they are pushed through the mixing nozzle. Once injected, the foam expands and hardens, keeping water, acids, greases, gases, insects, and rodents, etc., out of the conduit. The foam has good wetting and adhesion to metals, plastics, and concrete. A special ratchet tool is used to inject the foam from the side-by-side cartridges.

Polywater® FST MINI meets and exceeds all of the NEC code requirements for sealing conduit:  2011 NEC Articles 225.27, 230.8, 300.5 (G), 300.7 (A) on Raceway Seals, and 501.15 (B)(2).  It also meets Class 1, Div 2, cold storage entrances approximate R-Value of 6.5 per inch.

A properly constructed FST MINI example is pictured on the left in a transparent conduit demo. Note the placement of the “damming” strips wrapped around the cables. The dams create the void into which the liquid FST foam is injected and hold the rapidly expanding foam in place while it cures. The damming strips also separate cables to allow the foam to flow around them and prevent any leakage between the cables.


Product/Package Notes:

Polywater® FST MINI is recommended for small conduits (less than 1.5 inches (38 mm). It comes in a side-by-side 50 ml cartridge with 1:1 ratio. A TOOL-50-11 is needed to apply FST-MINI.

One Polywater® FST MINI cartridge seals approximately 10 1-inch ducts (25.4 mm). 

For larger conduits the FST-250 for Large Conduits is recommended (see sidebar).