A Foam Duct-Sealing System
for 2-inch/50-mm or Larger Conduits

  • Meets NEC Code Requirements 2011 NEC Articles 225.27, 230.8, 300.5(G), 300.7 (A) on Raceway Seals, and 501.15 (B)(2).
  • Reliable Holds 22 feet (6.7 m) of water head pressure and up to 90-foot (27 m) surges.
  • Seals Multiple Conduits Can seal conduits of all sizes and is reenterable.
  • Compatible Use with a wide range of cable jacket and conduit materials.
  • Solves Critical Application Class 1, Div 2, cold storage entrances approximate R-Value of 6.5/inch.

FST closed-cell duct sealant provides superior pressure-blocking power in the toughest environments. It stops methane and other gases to keep electrical systems intact. FST Duct Sealant is stronger, more chemically resistant, and cures 50 times faster than open-cell aerosol foams. The FST seal has excellent adhesion to PVC, rigid steel, EMT, IMC, fiberglass and polyethylene conduits. FST is a proven solution that has been used for years to protect switchgear, panels, riser poles, combiner boxes, meters, and all types of electrical and telecommunication apparatus. It creates a semi-permanent seal and is reenterable.


FST Seal Shown in a Transparent Tube.

A properly constructed FST seal is pictured on the left, installed in a transparent tube to show the structure of the seal inside the duct. Damming strips are wrapped around the cables to create a void into which the two-part liquid FST mixture is injected. The damming strips help contain the FST mixture at the mouth of the duct while it expands and hardens into a strong, resilient seal. The damming strips also separate cables so that the expanding foam can flow around them to prevent leakage between them. Inject the sealant with a high-ratio caulking gun for immediate protection of high-value network assets.


The photos below show some of the field uses for the Polywater FST Foam Duct Sealant.

FST installed in a U-guard

FST Duct Bank Installation

FST Duct Bank Installation

FST Riser Pole Installation

FST Riser Pole Installation

FST Usage at Solar Farms

FST Usage at Solar Farms

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Product/Package Notes:

  • Polywater FST is recommended for 2-inch (51 mm) or larger conduits.

  • It comes in a multi-use single-plunger caulking tube that uses a standard high-ratio caulking tool (TOOL-250).

  • For conduits smaller than 1.5 inches, the Polywater FST-MINI is recommended (see "related products" below).

  • The kit packages come with all the components needed to complete a proper seal.

Polywater FST Duct Sealant
Catalog # Package Description Units/Case
FST-250KIT1 1 - 8.5-oz two-part FST Foam Sealant caulking tube (cat# FST-250)
3 - mixing nozzles
4 - 24" foam damming strips (cat# FST-DAM)
1 - 12" abrasive strip
1 - pair disposable gloves
1 - positioning rod for foam dam
1 - pre-treating wipe (cat# HP-P158ID)
1 - resealing cap
1 - instruction sheet
FST-250KIT Same as FST-250KIT1 in a case of 6 6
FST-250 1 - 8.5-oz two-part FST Foam Sealant caulking tube
1 - mixing nozzle
1- resealing cap
MXR-30T-10 10-pack of mixing nozzles for FST-250 1
TOOL-250 1 - high-ratio caulking gun 1
FST-DAM 1 - 24" foam damming strip 24

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