Expansion Joints and Pre-Compressed Sealants

NSF-Compliant Watertight Joint System

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Field Installation
Potomac Water Filtration Plant
(Potomac, MD)

EMSEAL Recommends: Submerseal is recommended for use in most submerged applications. Its single bellows construction and increased silicone thickness makes it ideally suited to accommodate the significant head-pressure of continuous submersion. Submerseal has the same NSF/ANSI Standard 61-compliant physical properties as DSF. Whereas Submerseal is always constructed with a single bellows, at widths of 1 1/2-inch (40mm) and above DSF is constructed with multiple bellows.

DSF is a water-resistant,
joint-face-adhered, precompressed, primary seal for retrofit and new structural expansion joints and construction joints where contact with potable water is expected. Compliant to NSF/ANSI Standard 61 for contact with potable drinking water and with FDA Regulation CFR 177.2600 for indirect contact with food.

The DSF system features EMSEAL’s microsphere-modified acrylic adhesive infused into the cellular foam base material.

Standard sizes from 1/2" to 2" (12mm to 50mm) for temporary immersion applications under constant submersion. For larger sizes up to 4" (100mm) contact EMSEAL to determine conditions and application.

Note: Sizes under 1 1/2" (40mm) are manufactured with a single bellows. Larger sizes incorporate multiple bellows.

Movement Capability
+25% and -25% (Total 50%) of nominal material size.


Manufactured to resist and not contaminate conditions found
when expansion systems contact water and other clean liquids. Some examples are:

Municipal Water Tanks Restaurants
Potable Water Containers Cafeterias
Food Preparation Areas Food Storage
Spill Guards Clean Water Applications
Proximity to Cleanable, Wipeable, Nonporous Surfaces

Product Description

Featuring a silicone-bellows sealing surface and backed by an integral, pressure-resisting impregnated foam backing, the DSF System provides a lasting solution to joint sealing applications where constant exposure to non-corrosive liquids is expected. It also provides a seal which will not pose a contamination risk to liquids or solids which may be ingested.

The silicone bellows are compliant to NSF/ANSI Standard 61 for contact with potable drinking water. They are also in compliance with FDA Regulation CFR 177.2600 for indirect contact with food.

The system is comprised of (see Figure 1) precompressed, silicone-and-impregnated-foam hybrid installed into field-applied epoxy adhesive on the joint faces with the silicone bellows locked to the joint faces with a silicone sealant band.

For submerged applications this product has been tested in a hydrostatic-head pressure simulator to continuously resist water pressure of various levels without product deflection or leaking. Consult EMSEAL for the status and for application head pressure which will coincide with your situation.

Figure 1: DSF SYSTEM in Typical Installation (Single-sided)


Watertight —  DSF System is installed with the tensionless silicone bellows facing the liquid ensuring that watertightness is achieved.

Non-Invasive Anchoring — there are no hard metal-to-substrate connections with the DSF System. This includes embedded pins, anchors, screws, bolts or tracks, trays or rails. The system is locked to the joint faces by means of the 1) backpressure of the foam; 2) the epoxy adhesive, and 3) the injected silicone sealant band at the joint face to foam-and-silicone bellows interface.

Movement Capability +25% and -25% (50% total) of nominal material size. (See "Performance")

Versatility — The standard DSF SYSTEM color is off-white. Uniform bellows appearance, chemical resistance, and ability to handle variations in joint size through size-switching are among other system features.

Continuity of Seal — as in all EMSEAL expansion joint systems, continuity of seal through changes in plane and direction is an essential performance differentiator. The DSF SYSTEM utilizes EMSEAL’s exclusive "Universal- 90’s" (see below) which are factory-fabricated single-piece 90-degree units.

US Patent 9,200,437 Patent Pending

(Expanded Universal-90's information)

Factory-Fabricated Transition
s— EMSEAL's DSF expansion joint systems achieves continuity of seal through changes in plane and direction with DSF "Universal-90's".
DSF is manufactured in straight-run sticks which can be joined in the field to EMSEAL’s patent-pending "Universal-90" transitions.

Universal-90 Upturn Transition

Universal-90 Flipped-Over as Downturn Transition

These factory-fabricated single-piece 90-degree units have a 12-inch long leg and a 6-inch vertical piece on each side of the elbow. The Universal-90 transition pieces are symmetrically coated on both faces.  This allows them to be installed as an inside corner or as an outside corner.

In addition to guaranteeing watertightness, EMSEAL’s "Universal-90's" allow for much faster and secure installation by eliminating field cutting or notching and bending, at angles.


Figure 2: EMSEAL’s warranted watertight, factory-fabricated Universal-90’s at inside and outside corners ensure continuity of seal while eliminating field execution of directional changes.

"Universal-90", Factory-Fabricated Transition Pieces from EMSEAL ensure continuity of seal in expansion joints.


Double-Sided Straight-Run Option — The DSF SYSTEM is also available with double-sided protection manufactured with the water-resistant bellows on both sides of straight lengths for use in applications where exposure from two sides is possible. (See Figure 3)

Figure 3: DSF SYSTEM in Installation Where Exposure from Both Sides is Possible (Double-sided)


Capable of movements of +25%, -25% (50% total) of nominal material size.

The DSF SYSTEM will maintain its watertight capabilities and shape under a constant submerged depth (hydrostatic pressure) at various depths. Consult EMSEAL for your application.

Standard sizes from 1/2" to 2" (12mm to 50mm) for applications under constant submersion. For larger sizes up to 4" (100mm) contact EMSEAL to determine conditions and application.

Substrates must be solid, parallel, plumb and capable of resisting approximately 2.5 psi backpressure from the foam.

Applicable Standards: The Silicone coating meets or exceeds Compliant to NSF/ANSI Standard 61; NSF Standard 51; FDA Regulation CFR 177.2600; MIL-A-46146; and UL 94 Flame Class, 94 HB.


The DSF System is produced by coating an impregnated cellular foam with a non-corrosive liquid silicone sealant compliant to NSF/ANSI 61 Standard as well as FDA regulation CFR 177.2600.

The external silicone facing is factory applied to the foam at a width greater than the maximum offered extension and is cured before final compression.

The silicone application and curing takes place in a factory-controlled environment. In contrast to field-applied liquid sealant and backer rod installations, no movement takes place during curing that can cause deformation or stresses in the material.

When compressed, a bellows is created in the coating. As joint movement occurs the bellows simply folds and unfolds free of tension on the bondline, and virtually free of tensile stress in the silicone material.

The foam provides a resilient backing to the silicone coating, making the system capable of resisting head pressure and reasonable transient point loads.

The DSF System is supplied in 6.56 LF (2m) shrink-wrapped lengths (sticks). "Universal-90" factory-fabricated corners with a standard length of 6-inches (one leg) and 12-inches (other leg) are also available. DSF is precompressed to less than the joint size for easy insertion. After removal from the shrink-wrap and hard board restraining packaging, it expands gradually.


IMPORTANT: The following instructions are a summary. Refer to "DSF Install Data" and job-specific instructions of an EMSEAL technician for complete procedures. FOR PROFESSIONAL USE ONLY. KEEP OUT OF REACH OF CHILDREN.

• Store indoors at room temperature. Expansion is quicker when warm, slower when cold. Substrate temperature must range between 40°F (5°C) and 110°F (43°C).

Precautions: Wear chemical-resistant gloves and/or barrier hand cream when handling liquid sealant or epoxy. Remove promptly from skin with a commercial hand cleaner before eating or smoking. Avoid inhaling vapors.

Sequencing: Install factory-fabricated transition and/or termination pieces first. Connect straight run material to in-place terminations and transitions. Cut closing pieces 3/8-inch (10mm) longer than the opening to be joined. Compress material longitudinally to fit.

• Ensure nominal material size matches joint size.

• Mix epoxy and trowel a thin layer onto the joint faces to at least the depth of the DSF foam.

• Remove shrink-wrap packaging and hardboard.

• Wipe silicone facing using clean lint-free rag made damp with water.

• Insert material into joint to determined depth below the substrate surface.

• Inject a band of liquid silicone between mating bellows’ faces.

• Join lengths by pushing silicone-coated ends firmly together.

• Before the epoxy or the silicone cures, force the nozzle of the caulking tubes between the foam and the substrate and inject a silicone sealant band. Tool the overflow sealant into a corner bead between the top of the silicone bellows and the substrate.

• Clean Up: Remove epoxy or silicone sealant from equipment before it cures using MEK*, Toluene*, or Xylene*. These solvents are not effective after the epoxy or silicone has cured. Cured material may be removed by cutting it away with sharp tools or sandpapering.

*(Solvents mentioned or referred to are toxic and flammable. Observe solvent manufacturer’s precautions and refer to Material Safety Data Sheets as well as local and federal requirements for safe handling and use).

IMPORTANT Allow liquid silicone to attain a complete cure before filling area with liquid (7 days minimum).

• Maintenance: If the silicone bellows or sealant bands are damaged but remain intact, cut out the damaged area and recaulk. No primer is required. If the bond has been affected or the foam backing of the DSF is compromised, remove the damaged area, clean and prepare the substrates in accordance with instructions and reinstall new material.

Availability and Price

The DSF SYSTEM is available for shipment internationally subject to shipping restrictions for flammable and hazardous materials. Prices are available from local representatives and/or directly from the manufacturer. The product range is continually being updated, and accordingly EMSEAL® reserves the right to modify or withdraw any product without prior notice.



EMSEAL JOINT SYSTEMS LTD. 25 Bridle Lane, Westborough, MA 01581
EMSEAL LLC. 120 Carrier Drive, Toronto, ON M9W 5R1



1-800-526-8365 -- 508-836-0280 --  techinfo@emseal.com -- Fax: 508-836-0281

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