Connecting parts for water and food: LIQUIfit

Connecting Components for Water and Food: Liquifit — Compact Fittings for Secure Fluid Management

Liquifit connecting components offer a range of practical solutions for the food and beverage industry, as well as for aqueous process media. These components combine chemical resistance, hygienic geometries, and compact designs to minimize leaks, dead volume, and assembly effort. As an alternative to metallic screw-in and quick-release fittings, Liquifit systems are specifically designed for low friction, low particle generation, and easy disassembly.

Materials and Material Selection

Liquifit components are manufactured from food-grade polymers, often based on bio-based polymers or proven engineering plastics such as POM, PTFE-coated materials, or high-performance polyethylenes. Material selection depends on temperature range, chemical exposure, and mechanical stresses. For hot CIP processes, PTFE-protected sealing surfaces and temperature-stable plastics are required; for cooling systems, PE or POM variants are often sufficient. Corrosion-prone metals are replaced by polymer-based components, provided mechanical strength and pressure requirements allow.

Designs, Connections, and Geometries

The product family includes straight push-in connectors, elbows, tees, distributors, and bulkhead fittings. Compact push-in fittings allow tool-free assembly of hose or tube ends and are designed for standardized hose inner diameters. Variants with screw-in connections enable integration into existing threaded surfaces or housings. Sealing geometries utilize O-rings made of FKM, EPDM, or FDA-compliant silicones. For high temperature or chemical loads, EPDM or FFKM is recommended; for neutral aqueous media, EPDM or FDA silicone is sufficient.

Standard connections are available in metric threads (M, G) and NPT for international applications. Push-in connections are designed to be axially secured and prevent unintentional loosening under pressure. Bulkhead fittings offer a flat sealing surface for panels and tanks, with fastening nuts made of corrosion-resistant plastic or stainless steel.

Seals, Sealing Concepts, and Hygienic Design

Effective sealing reduces microbial contamination and product loss. Liquifit connecting components use sealing profiles with minimal dead volume and smooth transitions to prevent particle deposition. O-rings are designed to be replaceable and are easily accessible on most fittings. For sterile applications, smooth, easy-to-clean transitions without edges or sharp flanks are used. CIP and SIP compatibility is ensured by approved materials and designed temperature resistance.

Application Scenarios and Practical Examples

Practical Example 1: In a beverage filling line, Liquifit push-in straight connectors are used to connect the inlet and outlet lines of the filling heads. Tubing made of Santoprene hose Ø 8×1.5 mm is directly inserted into push-in fittings. The connections are equipped with EPDM O-rings with a sealing cross-section of 2.5×1.5 mm and withstand operating pressures up to 10 bar. Advantage: Tool-free assembly reduces downtime during nozzle changes.

Practical Example 2: In a dairy, bulkhead fittings are used to route CIP lines through partition walls. Bulkhead wall thickness 5–10 mm, bulkhead connection with EPDM seal and separate lock nut made of POM. Connections are positioned to allow direct access for cleaning nozzles. Result: Minimized risk of product accumulation and simplified sterilization without disassembling the line passage.

Practical Example 3: In an agitator circuit, 90° elbows connect the pump outlets to manifold bars. Material POM, FFKM seals at critical edges, hose connection Ø 12 mm. The assembly scheme considers maintenance openings and a maximum permissible operating temperature of 85 °C. The elbows reduce shear stress on sensitive suspensions and prevent cavitation at the pump discharge.

Assembly, Replacement, and Maintenance

Liquifit fittings are designed for quick assembly and uncomplicated maintenance. Push-in connections allow for a retractable disassembly tool or operating handle to specifically release hose ends. Screw-in variants use defined torques; assembly instructions specify material-friendly torque values. Seal seats are designed so that O-ring replacement works without special tools. For documented hygiene chains, regular visual inspection of all connecting components and scheduled O-ring replacement at defined service intervals are recommended.

Technical Characteristics and Alignment with Process Requirements

When selecting, pressure ratings, temperature ranges, hose diameters, media chemistry, and mechanical stress are crucial. Liquifit fittings typically cover pressure ranges up to 10–16 bar; special high-pressure variants achieve higher values with metal-reinforced housings. Temperature resistance varies depending on the polymer: standard plastics up to approximately 80–90 °C, glass fiber reinforced variants and PTFE-coated components up to over 120 °C. Acid- or alkali-resistant variants are available with FFKM O-rings and special polymer blends. For legal requirements regarding food contact, materials compliant with EU Regulation 10/2011 or FDA must be used.

Compatibility, Standards, and Certifications

Liquifit components are manufactured to be compatible with common hose systems and standard threads. For use in the food industry, requirements for purity, residue ingress, and cleanability apply. Pay attention to declared approvals (EU 10/2011, FDA) and documented material tests. For potentially explosive atmospheres, additional ATEX considerations are necessary if electrostatic charges can occur; polymer-based fittings should then be designed to be antistatic.

Product Variants and Selection Criteria

The following connection types are central to Liquifit applications:

• Push-in straight and elbow connectors, bulkhead fittings, distributors, tees, screw-in connectors

Choose a variant based on installation space, cleaning procedures, pressure and temperature requirements, and the connection type of the hose or tube. For regular disassembly, push-in solutions are advantageous; for permanently installed pipe runs, screw-in connections offer mechanical security and tightness.

Integration into Plant Planning

During plant planning, accessibility for assembly and inspectability of the connecting components should be considered early. Plan for service openings and replace critical connection points with easily accessible fittings. Use modular distributors to quickly isolate lines and facilitate product changes. Further technical components, sealing recommendations, and application examples can be found at https://maku-industrie.de/technik and specific project examples at https://maku-industrie.de/anwendungsbeispiele.

Procurement and Dimensional Accuracy

Accurate dimensions (EAN, series, hose diameter specifications, thread pitches) are the basis for interchangeability. When replacing existing metal connections with Liquifit polymers, dimensional and sealing verification is mandatory: tolerances of insertion depth, hose inner dimension, and O-ring cross-section significantly influence tightness. Order spare parts with precisely documented dimensions and material certificates to ensure conformity with hygiene and safety requirements.

Environmental Aspects and Recycling

Bio-based polymer variants reduce the proportion of fossil raw materials. However, note that not all bio-based plastics are automatically fully compostable or recyclable. Choose fittings that are clearly marked with their material class and disposal path to ensure traceability and recycling processes in production.

FAQ

1. Which sealing materials are suitable for hot water CIP?

For hot water CIP, EPDM seals or FFKM variants are preferred. EPDM offers good resistance to hot, alkaline cleaning agents; FFKM is suitable for particularly aggressive chemicals and higher temperatures. Material certificates for food contact must be checked.

2. How do I know if a Liquifit fitting fits my hose?

Compare the inner and outer diameters of the hose with the manufacturer's specifications for the fitting (insertion depth, gripper profile). Pay attention to tolerance specifications and the recommended insertion depth. If in doubt, perform a trial installation or consult the manufacturer's technical drawings.

3. Are Liquifit connecting components suitable for sterile applications?

Many Liquifit variants are designed for hygienic applications and can be CIP/SIP compatible, provided the materials and seals used are appropriately certified. For aseptic or sterile processes, in addition to material conformity, the constructive design against dead volume and documented cleaning validation are required.