Polyurethane, epoxy and acrylic injection are not interchangeable repair methods. Epoxy is generally selected when the objective is structural bonding in a suitable crack. Polyurethane is commonly selected to stop water or form a flexible seal in wet cracks, joints and voids. Acrylic or acrylate gel is selected when extremely low initial viscosity, adjustable reaction time and broad penetration are needed, especially for curtain injection behind a leaking structure.
The pump must match the complete material system: component ratio, viscosity, gel or working time, wetted-part compatibility, sealing, check valves, metering, mixing location and cleaning procedure. A pressure rating or a “two-component” label alone does not establish compatibility.
Manufacturers use the terms acrylic gel, acrylate gel and polyacrylate gel for related waterproofing product families. They should not be treated as one universal formula; the exact chemical base, component preparation and reaction mechanism in the current Product Data Sheet control.
Quick comparison: epoxy vs polyurethane vs acrylic injection
| Material family | Typical behavior before cure | Primary repair objective | Common applications | Pump and cleaning implications |
|---|---|---|---|---|
| Epoxy injection resin | Product-dependent viscosity; generally non-expanding and formulated to bond to the substrate. One published structural epoxy example, Sikadur 52, is approximately 200 cP when mixed. | Bonding and filling suitable cracks where structural continuity or high-strength adhesion is required by the repair design. | Dry or suitably prepared damp cracks in structural concrete, masonry and similar substrates, subject to the resin specification. | Match the pump to the required component ratio, mixed viscosity, pot life and pressure. The SU-999 Single-Component Injection Pump is the Adoration starting point for compatible pre-mixed epoxy delivered through one material path. Clean only with the resin and pump manufacturers' approved cleaner. |
| Polyurethane injection resin or foam | Available as flexible resins and water-reactive foams. Viscosity, expansion and reaction profile vary widely by product. One Sika water-reactive example lists approximately 230 cP for Part A and 290 cP for Part B. | Water stopping, flexible sealing, void filling or controlled expansion, depending on the selected formulation. | Active leaks, wet cracks, joints, penetrations, basements, tunnels, below-grade structures and selected void-filling work. | Component ratio and mixing method are product-specific. The SU-999 Single-Component Injection Pump is the Adoration starting point for compatible single-component polyurethane. Moisture-reactive residue must not be left to cure in the equipment. |
| Acrylic / acrylate gel injection | Very low initial viscosity, often close to water, with an adjustable reaction time in many systems. Sika Inject-215 is approximately 6 mPa·s and Sika Injection-304 approximately 7 mPa·s at 20°C as complete mixtures. | Permanent flexible waterproofing, broad-area penetration and sealing of fine water paths. | Curtain injection, membrane repair, construction joints, water-bearing cracks, masonry and water-saturated soil interfaces. | Fast-reacting systems often require a compatible Two-Component Injection Pump with separate A and B paths and mixing near the injection point. Water-based acrylic gel systems are commonly cleaned with water, but the current material data sheet controls. |
These viscosity figures are product examples, not universal ranges. Temperature, formulation, accelerator dosage and test method affect published values. Always use the current Product Data Sheet and Safety Data Sheet for the exact material being injected.
What is epoxy injection best suited for?
Epoxy injection is primarily a bonding method. A suitable low-viscosity epoxy can penetrate a prepared crack and cure as a high-strength adhesive. For example, Sika describes Sikadur 52 as a two-component structural epoxy for gravity feed or pressure injection into cracks and publishes a 2:1 ratio by volume. That example alone shows why pump selection cannot be based only on the word “epoxy”: a fixed 1:1 pump would not meter a 2:1 product correctly.
Epoxy should not be chosen simply because a crack is visible. The repair designer must evaluate crack movement, moisture, contamination, access and the structural objective. A moving joint or an uncontrolled active leak may require a different first step or a different material family.
For a focused comparison of epoxy and polyurethane equipment, read the epoxy injection pump vs polyurethane injection pump guide.
What is polyurethane injection best suited for?
Polyurethane injection covers several chemistries rather than one universal product. Water-reactive foams are commonly used to stop water intrusion and fill leaking paths; flexible polyurethane resins may be used for durable sealing. Expansion, cell structure, flexibility and reaction speed must be checked in the material documentation.
Sika Injection-101 US, for example, is a water-reactive polyurethane that forms a dense flexible foam and is intended for water stopping in cracks, joints and cavities. Its published properties and cleaning method apply to that specific product, not to every polyurethane grout.
For compatible single-component polyurethane or pre-mixed epoxy delivered through one material path, the Adoration option is the SU-999 Single-Component Injection Pump. Two-component polyurethane or epoxy systems require equipment that matches the specified ratio and mixing process. The DN-999 Two-Component Hopper-Fed Injection Pump is designed for compatible 1:1 systems; it is not suitable for a material that requires 2:1, 3:1 or another ratio.
What is acrylic or acrylate gel injection?
Acrylic injection gel, also called acrylate or polyacrylate gel, is a water-compatible injection material used for flexible waterproofing. Before reaction, selected systems have extremely low viscosity and can move through fine cracks, pores, interfaces and permeable soil zones that a more viscous material may not reach as readily.
“Close to water” should still be supported by the exact product data. Sika publishes approximately 6 mPa·s for Sika Inject-215 and approximately 7 mPa·s for Sika Injection-304 at 20°C. For context, water is roughly 1 mPa·s near room temperature. The comparison explains the strong penetration potential without implying that every acrylic gel has the same viscosity.
Many acrylic systems are hydrophilic and remain flexible after cure. Some can reversibly absorb and release water, helping them maintain a seal where moisture conditions change. They are normally used for waterproofing rather than structural bonding.
What is curtain injection?
Curtain injection is a remedial waterproofing method that creates a gel barrier behind a leaking wall, slab or other structural element. Holes are drilled through the structure, packers are installed, and a compatible low-viscosity injection material is delivered beyond the structure. The material spreads through interfaces, fine voids and suitable surrounding ground, then gels to form a continuous or overlapping waterproof curtain on the water-entry side.
This approach is useful when the exterior waterproofing face cannot be excavated or directly accessed. Typical candidates include below-grade walls, tunnels, shafts, elevator pits and other structures with distributed leakage rather than one isolated crack.
Curtain injection is not blind pumping. Sika's published procedure calls for a site survey before work near foundations or existing structures and warns installers to identify drainage systems and open pipes near the injection area. Test injection, recorded material travel, controlled pressure and a planned packer pattern are essential because soil, voids and water paths can produce unpredictable consumption.
Why is acrylic gel used for curtain injection?
Acrylic gel is well suited to curtain injection because its low initial viscosity supports broad penetration before gelation. Adjustable reaction time lets the installer balance travel distance against washout risk and site conditions. Once reacted, a compatible flexible gel can create a water-resistant barrier behind the structure and within connected pores or soil voids.
The objective is not maximum pressure. Sika's curtain-injection guidance favors slow, low-pressure injection over rapid, high-pressure delivery. The correct pressure depends on the structure, packers, surrounding ground, water conditions and material supplier's procedure.
How a suction-fed Two-Component Injection Pump works
In a suction-fed system, each material side has its own pickup line. As the piston cylinder reciprocates, the intake stroke creates suction, or local negative pressure relative to the material container, at the inlet. The corresponding inlet check valve opens and material is drawn through the suction hose from its container. On the discharge stroke, the valve sequence directs the metered material toward the pressure hose. A filter, screen or suction strainer at each pickup helps prevent debris from entering valves, seals and the mixing assembly.
The A and B components remain in separate material paths through suction, metering and pressurization. For fast-reacting acrylic gel, they should meet only at a compatible mixing head and static mixer positioned as close to the injection point as the approved system permits. Sika's injection-equipment guidance states that fast-reacting polyacrylate components are introduced separately to the mixing head and mixed in a static mixer there. This minimizes the volume of reacted gel that can remain inside shared equipment.
The DA-999 Two-Component Suction-Fed Injection Pump uses two separate plastic suction filter cylinders, one for Component A and one for Component B. Each filter cylinder is approximately 7 cm (2.8 in.) long and 3 cm (1.2 in.) in diameter. The reciprocating pump creates suction, or negative pressure, to draw each component through its own filter cylinder and material path before pressurization. This arrangement is intended for compatible acrylic or acrylate gel workflows while helping keep debris out of the inlet valves and pump. Before use, confirm the selected gel's A:B ratio, viscosity, gel time, wetted-material requirements, hose arrangement, mixing head, seals, check valves and cleaning procedure against the current DA-999 documentation and the material manufacturer's instructions.
Hopper-fed vs suction-fed injection pumps
| Selection factor | Hopper-fed architecture | Suction-fed architecture |
|---|---|---|
| Material supply | Prepared material is poured into one or more pump-mounted hoppers. | Separate pickups draw components directly from their containers through filters or strainers. DA-999 uses two plastic suction filter cylinders, approximately 7 cm long and 3 cm in diameter. |
| Typical advantage | Easy visual monitoring, priming and handling for compatible materials and normal job volumes. | Separate container pickup, less material transfer and a layout well suited to keeping fast-reacting components apart until the mixing head. |
| Key compatibility checks | Hopper geometry, pump seals, inlet and outlet valves, metering ratio, pot life and cleaning access. | Suction sealing, pickup hose restriction, strainer condition, check-valve performance, metering ratio, cavitation risk and cleaning access. |
| Adoration example | DN-999 Two-Component Hopper-Fed Injection Pump for compatible 1:1 epoxy or polyurethane systems. | DA-999 Two-Component Suction-Fed Injection Pump for compatible acrylic or acrylate gel workflows. |
Low viscosity does not automatically prevent a hopper-fed pump from building pressure. Pressure generation depends on the displacement mechanism and the integrity of the complete fluid path, including seals, packings, inlet and outlet check valves, hose connections and the material itself. Some acrylic gel products can be processed by hopper-fed equipment when the manufacturer approves the configuration.
DA-999 is the better Adoration starting point for ultra-low-viscosity, fast-reacting acrylic gel because its feeding architecture is designed around separate suction pickups and late mixing. The reason is system compatibility and process control, not a claim that thin material makes every hopper pump incapable of pressure.
Can a two-component epoxy or polyurethane pump be used for acrylic gel?
Possibly, but “two-component” is not enough. The pump must match the acrylic gel's required ratio, component viscosities, reaction time, chemical compatibility and mixing location. Its seals and wetted metals must be approved, its check valves must meter reliably, and the mixed section must be short enough to clean before gelation. A system designed around long-pot-life epoxy may have an unsuitable mixer, dead volume or cleaning workflow for a fast acrylic gel.
DN-999 is a Two-Component Hopper-Fed Injection Pump. Its intended 1:1 epoxy and polyurethane workflow differs from the suction-fed acrylic-gel workflow for which DA-999 is the better starting point. Final compatibility must still be confirmed for the exact material.
How should injection pumps be cleaned?
Acrylic or acrylate gel systems
Follow the current gel manufacturer's cleaning instructions. Water-based acrylic gel systems commonly use water for immediate cleaning. Sika's current data for Sika Inject-215 and Sika Injection-304 directs users to clean tools and injection equipment with water; cured material must be removed mechanically. Do not recommend xylene, acetone or engine oil as a default acrylic-gel cleaning method.
Epoxy systems
Use the cleaner specified by the epoxy manufacturer and confirmed compatible with the pump's seals, hoses and valves. Observe the material's pot life and clean before cure. A cleaner approved for one epoxy formulation is not automatically correct for another.
Polyurethane systems
Use the exact compatible solvent, proprietary flush or cleaner required by the polyurethane and equipment manufacturers. Some polyurethane instructions specify xylene; others specify a proprietary washing agent. Water must not be introduced into a moisture-reactive polyurethane system unless the approved procedure expressly calls for it. Review the detailed polyurethane injection pump cleaning guide before establishing a shop procedure.
There is no universal cleaning fluid for every resin and every pump. Plan the flush before injection starts, keep A and B sides separate, relieve pressure safely, and dispose of contaminated cleaning fluid under the applicable Safety Data Sheet and local requirements.
Injection packer and coupler selection
Select the injection packer and coupler as one material-delivery connection. The repair material, injection objective, port geometry and mating head determine the practical starting point. The table below summarizes common Adoration configurations; the exact material instructions, working-pressure ratings, threads, valves and substrate conditions still control the final setup.
Injection packer selection by application
| Adoration injection packer or port | Common compatible material workflow | Best-fit application | Connection and selection note |
|---|---|---|---|
| S-10 Instant Injection Packer | Compatible epoxy, polyurethane and acrylic or acrylate injection systems | Drilled mechanical-packer injection into cracks or internal pathways where the specified system requires a pressure-capable port | Zerk-style connection; verify the drill size, sleeve seal, material compatibility and complete system pressure rating |
| M6-M8 Surface Packer | Epoxy injection | Surface-port epoxy injection for suitable concrete crack repair, normally with a compatible surface seal | No drilled mechanical anchor; the concrete face, bonding method and surface seal must support the written injection procedure |
| 5/8-inch Button Head Plastic Packer | Especially suited to compatible acrylic or acrylate gel workflows | Curtain injection through walls or slabs where high-flow delivery to the area behind the structure is required | Use a matching button-head/slide connection. Additional application: this packer is also used for compatible slab-lifting workflows |
The S-10 is the broadest of these three port options by resin family, but that does not make every S-10 setup interchangeable. Acrylic gel ratio, reaction time and required flow path may favor the larger button-head configuration for curtain work. Conversely, M6-M8 surface packers are aimed at suitable epoxy crack repair from the concrete face rather than behind-structure curtain injection.
Grease and slide coupler selection
| Adoration coupler | Compatible construction workflows | Typical matching packer or port | Selection note |
|---|---|---|---|
| B33 Steel Zerk Fitting Coupler | Epoxy injection, polyurethane injection, and acrylic or acrylate injection | Zerk-type mechanical packers and injection ports, including compatible S-10 and M6-M8 configurations | Use only when the zerk profile, jaw engagement, check-valve operation, pressure rating and resin/cleaner compatibility are confirmed |
| 1/8-inch Female Slide Coupler | Acrylic or acrylate curtain injection; also compatible slab-lifting workflows | 5/8-inch Button Head Plastic Packer | Use the slide coupler and button-head packer as a matched connection; confirm hose interface, valve opening, flow capacity and system pressure rating before injection |
Quick selection answer: use the B33 Steel Zerk Fitting Coupler for a verified zerk-style packer connection across compatible epoxy, polyurethane or acrylic injection work. For acrylic curtain injection using the 5/8-inch Button Head Plastic Packer, use the matching 1/8-inch Female Slide Coupler. The same button-head and slide-coupler pairing can also be selected for a compatible slab-lifting system.
Field selection workflow
- Define the repair objective: structural bonding, active water stopping, flexible sealing, void filling or a behind-structure waterproof curtain.
- Select the exact material: use the current Product Data Sheet, not only the generic family name.
- Record the pump-critical data: A:B ratio, viscosity of each component, gel or pot life, temperature limits, pressure guidance, wetted-material compatibility and cleaning fluid.
- Choose the feeding architecture: hopper-fed or suction-fed based on the approved workflow, container handling, metering and mixing location.
- Keep fast components separate: place the approved mixing head and static mixer near the injection point.
- Build the complete pressure path: verify hose, valve, coupler and mechanical injection packer ratings and connections.
- Run a controlled field trial: start at low pressure, observe material travel and returns, record consumption, and adjust only within the material and project procedure.
For below-grade diagnosis and packer planning, see the underground waterproofing leak repair field guide. Contractors can also compare the full Adoration injection pump collection.
Frequently asked questions
What is the difference between epoxy, polyurethane and acrylic injection?
Epoxy is primarily used to bond and fill suitable structural cracks. Polyurethane is commonly used to stop water, form a flexible seal or expand into leaking paths and voids. Acrylic or acrylate gel is a very-low-viscosity flexible waterproofing material used for fine penetration, area sealing and curtain injection. The exact product specification controls every application.
What is curtain injection?
Curtain injection creates a waterproof gel barrier behind a leaking structural element. Installers drill through the wall or slab, inject through packers, and distribute compatible low-viscosity material into interfaces, voids and suitable surrounding soil where it gels into an overlapping waterproof curtain.
Why is acrylic gel used for curtain injection?
Acrylic gel combines very low initial viscosity with adjustable reaction time and flexible waterproofing behavior. This lets it travel behind the structure through fine pathways before gelation. Published Sika examples are approximately 6–7 mPa·s at 20°C, but the actual product data must be checked.
Can a Two-Component Injection Pump for epoxy or polyurethane be used for acrylic gel?
Only if the manufacturer confirms compatibility with the acrylic gel's ratio, viscosity, reaction time, wetted materials, metering accuracy, mixing head and cleaning procedure. Being a Two-Component Injection Pump does not by itself establish suitability.
What is the difference between a hopper-fed and suction-fed injection pump?
A hopper-fed pump receives prepared material through pump-mounted hoppers. A suction-fed pump draws each component from a separate container through pickup hoses and strainers. For fast acrylic gel, suction-fed architecture can simplify separate component handling and late mixing, provided the pump and gel are approved as a system.
How should injection pumps be cleaned?
Use the cleaning method specified for the exact material and approved for the pump. Water-based acrylic gels commonly use water. Epoxy and polyurethane systems may require different compatible cleaners or proprietary flushes. Never treat xylene, acetone, water or engine oil as a universal pump cleaner.
Which Adoration injection pump matches each material workflow?
Use the SU-999 Single-Component Injection Pump for compatible single-component polyurethane or pre-mixed epoxy delivered through one material path. Use the DN-999 Two-Component Hopper-Fed Injection Pump for compatible 1:1 epoxy or polyurethane systems. Use the DA-999 Two-Component Suction-Fed Injection Pump as the Adoration starting point for compatible acrylic or acrylate gel and curtain-injection workflows. Final selection always follows the exact material documentation.
Which injection packer and coupler should be used for epoxy, polyurethane or acrylic injection?
The S-10 Instant Injection Packer is a mechanical-packer option for compatible epoxy, polyurethane and acrylic injection systems and commonly mates to a verified zerk coupler such as the B33 Steel Zerk Fitting Coupler. The M6-M8 Surface Packer is intended for suitable surface-port epoxy crack repair. For acrylic curtain injection, the 5/8-inch Button Head Plastic Packer with the matching 1/8-inch Female Slide Coupler provides the application-specific pairing; this pairing is also used in compatible slab-lifting workflows.
Equipment and technical references
Adoration equipment references
- SU-999 Single-Component Injection Pump
- DN-999 Two-Component Hopper-Fed Injection Pump
- DA-999 Two-Component Suction-Fed Injection Pump
Independent technical references
- Sika Injection Systems: material selection and curtain injection process
- Sika Injection-304 Product Data Sheet: viscosity, mixing, pump and water cleaning
- Sika Inject-215: curtain injection, viscosity, static mixing and water cleaning
- Sikadur 52 structural epoxy injection product information
- Sika Injection-101 US polyurethane product information
- DESOI curtain-injection equipment: suction systems, metering, check valves and mixing heads
- WIWA injection equipment: suction-fed acrylic-gel systems and separate mixing units
External manufacturer and product names are cited only to identify public technical sources and product-specific examples. No affiliation, certification or endorsement of Adoration equipment by those manufacturers is stated or implied.
Bottom line
Choose the material first and the pump second. Epoxy is the structural-bonding starting point for suitable cracks. Polyurethane is the water-stopping or flexible-sealing starting point for many wet leaks and voids. Acrylic or acrylate gel is the penetration and curtain-injection starting point when a flexible waterproof barrier must form behind the structure.
Within the Adoration range, SU-999 is the Single-Component Injection Pump for compatible single-component polyurethane or pre-mixed one-path epoxy workflows. DN-999 is a Two-Component Hopper-Fed Injection Pump for compatible 1:1 epoxy or polyurethane systems. DA-999 is a Two-Component Suction-Fed Injection Pump and is the better starting architecture for compatible ultra-low-viscosity acrylic gel and curtain-injection workflows. In every case, the selected resin's ratio, viscosity, reaction time, mixing and cleaning documents determine final compatibility.
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