Polywater FST is a two part foam sealant for electrical conduits and cable penetrations. It makes airtight and watertight seals and is fire retardant. Polywater recommends FST-250 for conduits 2 in (50 mm) and larger, and FST-MINI for conduits under 2 in (50 mm). The comparison of FST and AFT is in Polywater AFT vs FST. This article covers the catalog numbers.
| Catalog # | Package | Units per case |
|---|---|---|
| FST-250KIT1 | Kit with one 8.5 oz (240 g) two part FST-250 tube, 3 mixing nozzles, 4 damming strips, abrasive strip, gloves, foam dam positioning rod, pre-treating wipe, resealing cap and instructions. Caulking tool sold separately (TOOL-250). | 1 |
| FST-250KIT | Six FST-250KIT1 kits | 6 |
| FST-250 | One 8.5 oz (240 g) two part FST-250 tube, one mixing nozzle and one resealing cap | 12 |
| MXR-41T-10 | Ten pack of mixing nozzles for FST-250 | 1 |
| TOOL-250 | High ratio caulking gun | 1 |
| FST-DAM | 24 in (61 cm) foam damming strip | 24 |
| Catalog # | Package | Units |
|---|---|---|
| FST-MINI-1 | One 50 ml FST-MINI cartridge, 2 mixing nozzles, 6 foam discs, gloves and instructions | 1 |
| FST-MINI-1G | FST-MINI-1 plus TOOL-50-11 dispensing tool (US only) | 1 |
| FST-MINI-B6 | Six FST-MINI units | 1 |
| FST-MINI-B6G | Six FST-MINI units plus TOOL-50-11 (US only) | 1 |
| TOOL-50-11 | Dispensing tool for FST-MINI | 1 |
| MXR-20T-10 | Ten pack of mixing nozzles for FST-MINI | 1 |
These are Polywater's published values for FST.
| Item | Polywater specification |
|---|---|
| Water head | Holds 22 ft (6.7 m) continuous, surges to 90 ft (27 m) |
| Service temperature | -20 F to 200 F (-30 C to 120 C) |
| Fire rating | Meets UL 94 HBF; self-extinguishes after 1 minute of flame |
| UL classification | Surface burning characteristics of caulking and sealant |
| Codes | NEC Class 1, Division 2 sealant (225.27, 230.8, 300.5(G), 300.7(A), 501.15(B)(2)); CSA and TIA references |
| Compressive strength | 145 psi (1.00 N/mm2), ASTM D1621 |
| Tensile strength | 120 psi (0.83 N/mm2), ASTM D1623 |
| Adhesion | PVC, RGS, PE, EMT, IMC |
| Re-enterable | Yes, sealant can be removed for future cable installation |
| Chemical resistance | Gasoline, oils, dilute acids and bases, most unsaturated hydrocarbons |
| Certification | NSF certified for nonfood compounds, S2 |
See the Adhesives and Sealants category in the store, or contact Powertech Associates for case quantities and help sizing a job.
Last updated: November 2026.
