Connecting parts for water and food : LIQUIfit

Connecting Components for Water and Food: Liquifit – Technical Overview and Application

Liquifit stands for compact, reliable connecting components specifically designed for conveying water and food-grade media. The product family includes Push-In Fittings, screw-in connectors, plug connectors, cross fittings, elbow fittings, distributors, and bulkhead fittings in versions with metallic and bio-based polymers. Crucial factors are material selection, seal design, connection geometry, and approvals; these determine pressure, temperature, and media resistance, cleanability, and ease of assembly.

Materials and Material Properties

Liquifit connecting components are made from POM, PA, PPS, stainless steel (mostly AISI 316), and a bio-based polymer. POM offers good lubricity and chemical resistance, PA increases impact strength, PPS reduces thermal deformation at higher temperatures, and stainless steel provides maximum corrosion resistance and food safety. The bio-based polymer combines a low CO₂ footprint with sufficient resistance to water and many food ingredients; it is particularly suitable for applications with low to medium temperatures and moderate pressure.

Seals, Sealing Materials, and Media Compatibility

Seals in Liquifit components are typically made from EPDM, FKM (Viton), or FDA-compliant silicones. EPDM is recommended for hot water, cleaning agents, and many aqueous food solutions. FKM is used for increased temperature resistance and oil contact. Silicone seals offer very good temperature flexibility and are available in food-grade variants for direct food contact. When selecting, compatibility with cleaning and disinfection agents (acids, alkalis, peroxides, alcohols) must be considered; manufacturer data sheets and chemical resistance lists should be consulted.

Connection Types, Sealing Concepts, and Assembly

Liquifit offers Push-In Fittings for quick plug-in assembly, screw-in connectors for permanent connections, bulkhead fittings for pass-throughs through container walls, and mounting flanges for modular setups. Push-In configurations feature an automatic gripping and sealing system; the hose is inserted axially, the internal clamping part absorbs tensile forces, and the seal ensures media sealing. Screw-in connectors use metric or BSP threads; for metal housings, self-locking lock nuts or O-ring seating surfaces are common. Bulkhead fittings are available as pass-through or union variants to allow service access without line disconnection.

Temperature and Pressure Range

Typical operating pressures, depending on material and design, range between 6 bar (fine bio-based polymers at higher temperatures) and 16 bar (PA/POM/metal fittings at room temperature). Temperature specifications range from −20 °C to +120 °C, with stainless steel and PPS versions allowing higher continuous operating temperatures. For applications with periodic temperature peaks or thermal cycles, attention must be paid to thermal expansion and seal aging.

Hygiene, Cleanability, and Approvals

For food and beverage applications, food approvals (e.g., EU Regulation 10/2011, FDA conformity) and cleaning resistance are crucial. Liquifit components are designed to minimize flow stagnation; smooth internal surfaces and optimized edge geometries reduce biofilm risks. For CIP (Cleaning in Place) and SIP (Sterilization in Place), temperature-resistant materials and seals with chemical resistance to cleaning agents, as well as suitable surface roughness, are specified. For applications with steam sterilization, metallic variants or high-performance plastics like PPS are preferred.

Dimensions, Hose Compatibility, and Connection Systems

Liquifit connecting components are designed for standard hose inner diameters (ID) and outer diameters (OD); common nominal sizes range from 4 mm to 25 mm ID. Selection considers wall thickness and hose material (PVC, PU, silicone, EPDM). Crimp connections are intended for permanent connections, Push-In for modular, demountable line routings. When integrating into existing systems, transition adapters (e.g., to NPT, BSP) and O-rings with suitable cross-sections are required.

Application Fields Industrial & Food Processing

Liquifit is used in beverage filling plants, cooling water circuits, dosing and mixing systems, laboratory and sampling lines, and packaging machines. The products are suitable for conveying drinking water, process water, fruit juices, low-viscosity oils, and low-suspension foods. In pharmaceutical and cosmetic production, chemically high-purity variants with special seals are used.

Practical Examples

Example 1: In a filling line for carbonated beverages, a Liquifit stainless steel Push-In distributor connects several dosing lines to a central feed. The smooth internal surface reduces deposits, the EPDM O-rings withstand pressures up to 10 bar, and the plug connections allow tool-free maintenance during a shift change.

Example 2: In the CIP return of a dairy, a bio-based polymer elbow fitting replaces a traditional PA solution. The design reduces dead spaces and achieves a tight connection at moderate temperatures with a suitable silicone O-ring; the CO₂ footprint of the components improves the sustainability rating of the line.

Example 3: In laboratory automation and sampling, micro screw-in connectors made of POM are used to quickly connect aqueous buffer solutions under 6 bar. The slim connection seat allows easy integration into device cassettes without additional adapters.

Planning Notes and Integration

During planning, attention must be paid to flow resistance due to tight bends, thermal expansion, and strain relief. Pipe routing should avoid kink zones, and hose lengths should be designed to minimize pressure losses and cavitation. In multi-component systems, chemical compatibility of all seals and transition materials must be ensured. Use appropriate assembly wrenches and torque specifications for screw connections to prevent stress cracks in polymer parts. Further technical information and application cases can be found at https://maku-industrie.de/technik and https://maku-industrie.de/anwendungsbeispiele.

Selection Criteria for Purchasing

Important criteria are: operating pressure/temperature, media type, cleaning procedure (CIP/SIP), approvals (EU/FDA), material and seal type, assembly effort, and TCO (lifecycle costs). Pay attention to the availability of replacement seals and standard adapter dimensions. If sustainability is relevant, check the documentation for the bio-based polymer and life cycle analyses.

• Available variants: Push-In, Screw-in, Bulkhead, Elbow, Cross, Distributor; Materials: POM/PA/PPS/Stainless Steel/Bio-based Polymer; Seals: EPDM/FKM/Silicone (food-grade)

Assembly and Maintenance Tips

Before assembly, connection dimensions and sealing surfaces must be cleaned. For Push-In Fittings, cut the hose end cleanly, squarely, and burr-free. Use appropriate thread sealant or an O-ring for screw threads; avoid overtightening. Replacement intervals for seals depend on temperature cycles, cleaning agents, and the medium used; visual inspection and pressure testing after maintenance are mandatory.

Compatibility and Spare Parts

Liquifit components are often modularly compatible with other Legris systems; nevertheless, check dimension tables and manufacturer lists. Replacement seals are available as standards; for bio-based materials, special service kits may be necessary. For special connections or OEM configurations, coordination with the technical department is advisable.

FAQ

1. Which seals are best suited for hot water and CIP cycles?

EPDM seals are generally the first choice for hot water and many alkaline/acidic CIP chemicals. For aggressive organic cleaning agents or higher temperatures, FKM or special silicone variants should be considered; always check manufacturer's chemical resistance and temperature range.

2. Are Liquifit connecting components approved for drinking water applications?

Many Liquifit versions have food and drinking water approvals (e.g., EU and FDA conformity). The specific suitability depends on the chosen material and seal; request conformity declarations and test certificates if needed.

3. When is a stainless steel fitting preferable to polymer?

Stainless steel is essential for high temperatures, intensive chemical exposure, steam sterilization, or when maximum corrosion resistance is required. Polymer variants are suitable for cost-effective, lightweight installations with moderate conditions; bio-based polymers also offer ecological advantages for suitable applications.