Introduction to the EXTRUTEX SL Series Water Cooled Chillers

In modern industrial manufacturing, especially in the plastics, rubber, extrusion and injection-moulding sectors, precise temperature control of process water is not a luxury – it is a fundamental requirement for product quality, cycle-time reduction and equipment longevity. The EXTRUTEX SL Series water-cooled chillers have been developed to meet exactly these demands. Designed in Austria and manufactured in state-of-the-art facilities in Nanjing and Shanghai, the SL Series combines European engineering philosophy with the cost-efficiency and production scale of Chinese manufacturing.

Water-cooled chillers differ fundamentally from air-cooled units. Instead of rejecting heat directly to the ambient air via fans and finned condensers, a water-cooled chiller transfers the heat load to a secondary cooling-water circuit that is normally connected to a cooling tower or central cooling-water system. This architecture yields higher thermodynamic efficiency, quieter operation, smaller footprint for a given capacity, and superior performance in high-ambient-temperature environments – conditions frequently encountered in Asian and Middle-Eastern production plants as well as in densely packed European factory halls.

The EXTRUTEX SL Series covers refrigeration capacities from 15 kW (SL-5W) up to 180 kW (SL-60W). All models are built around proven rotary (scroll or reciprocating) compressors, high-efficiency shell-and-tube condensers, and either serpentine-pipe or shell-and-tube evaporators depending on capacity. The chilled-water circuit is closed and insulated, while the water tank is fabricated from stainless steel and fitted with a heat-insulation layer. Multiple layers of electronic and mechanical protection – high/low pressure, antifreeze, flow, compressor overload and pump overload – ensure safe, continuous operation around the clock.

Because the design originates in Austria, the units inherit a strong emphasis on serviceability, clear documentation, and long component life. Manufacturing in Nanjing and Shanghai allows EXTRUTEX to offer competitive pricing and short lead times without compromising on the quality of critical components such as compressors, expansion valves and pressure controllers. The result is a product line that is equally at home on a European extrusion line producing precision profiles and on a high-volume Asian injection-moulding plant running 24/7.

This document provides a complete technical overview of the SL Series: performance characteristics, working principle with a fully English schematic, detailed specifications for every model, application guidance, and the manufacturing and quality philosophy that underpins the EXTRUTEX brand.

Performance Characteristics

The following performance features define the daily operational experience of an EXTRUTEX SL Series water-cooled chiller. Each point has been engineered to solve real-world problems encountered on production floors.

Detailed Explanation of Key Features

Temperature stability is the single most important performance metric for any process chiller. In extrusion of polyolefins, PVC or engineering plastics, a variation of only a few degrees in cooling-water temperature can shift the crystallisation behaviour of the polymer, change surface gloss, or cause dimensional drift that takes the product outside tolerance. The microcomputer-controlled system of the SL Series continuously monitors the leaving-water temperature via a high-accuracy sensor and modulates compressor operation (or stages multiple compressors on larger models) to keep the temperature within ±1 °C of the set point. This level of control is achieved without the need for expensive inverter drives on every unit, keeping both capital cost and complexity under control.

Protection philosophy follows the principle of “fail safe, not fail silent”. High-pressure and low-pressure switches monitor the refrigerant circuit; an antifreeze thermostat or switch prevents the evaporator from freezing if the chilled-water flow is interrupted; a flow switch or differential-pressure switch confirms that the pump is delivering water; and thermal overload relays protect both the compressor and the pump motors. All these devices are wired into a common fault circuit that stops the unit and illuminates a clear alarm indicator, allowing maintenance staff to diagnose the root cause quickly.

Material and insulation choices reflect long-term reliability. Stainless-steel tanks resist corrosion from treatment chemicals or residual process contaminants. The insulation layer reduces heat gain from the surrounding plant environment, which is especially valuable when the chiller is installed in a warm factory hall. Insulated freeze pipelines minimise energy losses and eliminate the dripping of condensation that can create slip hazards or damage nearby electrical equipment.

Condenser efficiency is critical because the cooling-water circuit is usually shared with other plant services. A well-designed shell-and-tube condenser maintains high heat-transfer rates even with moderate fouling factors, reducing the frequency of chemical cleaning and the associated production interruptions. The design also allows the condenser to be cleaned mechanically from the water side without dismantling the entire refrigerant circuit – a practical advantage for maintenance teams.

Working Principle Diagram

The schematic below illustrates the complete refrigeration and chilled-water circuits of a typical EXTRUTEX SL Series water-cooled chiller. All labels are in English and numbered for clarity. The diagram is free of Chinese characters and is suitable for international technical documentation, training materials and customer manuals.

How the Circuit Works

The refrigeration cycle begins at the compressor (1). Low-pressure, low-temperature refrigerant vapour is drawn from the evaporator and compressed to a high-pressure, high-temperature vapour. This vapour enters the shell-and-tube condenser (2), where heat is rejected to the cooling-water circuit that returns to the cooling tower. The refrigerant condenses into a high-pressure liquid, passes through the filter drier (3) to remove moisture and contaminants, and then expands through the expansion valve (4). The resulting low-pressure, low-temperature mixture enters the evaporator (5), where it absorbs heat from the process water circulating through the water tank (10) and pump (12). The now-vapourised refrigerant returns to the compressor, completing the cycle.

Safety devices continuously monitor the system: the antifreeze switch (7) protects against evaporator freeze-up, the float switch (8) can signal low water level, the temperature sensor (9) provides the control signal to the microcomputer, and the high- and low-pressure controllers (14, 15) shut the unit down if pressures leave the safe operating envelope. The pressure-relief valve (13) provides a final mechanical safeguard against over-pressure.

Technical Specifications – SL Series

The table below lists the complete technical data for models SL-5W through SL-60W. All capacities are rated under the standard condition of 12 °C chilled-water inlet / 7 °C outlet and 35 °C ambient air-side temperature. Actual performance may vary slightly with site conditions; EXTRUTEX application engineers can provide selection software and derating factors for non-standard temperatures or altitudes.

Typical Applications

The EXTRUTEX SL Series is designed for continuous industrial duty. The most common applications include:

• Plastics extrusion – cooling of calibration tanks, vacuum tanks, haul-off rollers and downstream equipment on PE, PP, PVC, ABS and engineering-plastic lines. Stable water temperature is essential for dimensional accuracy of pipes, profiles, sheets and films.
• Injection moulding – mould cooling to reduce cycle times, improve surface finish and minimise warpage. Smaller SL models are frequently paired with individual machines; larger models serve central cooling systems for multi-machine halls.
• Blow moulding and thermoforming – precise control of mould and tooling temperatures for consistent wall thickness and optical quality.
• Rubber processing – cooling of mixers, calenders and extruders where temperature control affects cure characteristics and energy consumption.
• Laser and machine-tool cooling – when a plant already has a cooling-tower circuit, the water-cooled chiller provides a compact, efficient source of chilled water for high-power lasers, spindles and hydraulic systems.
• Food and pharmaceutical packaging – cooling of forming tools and sealing stations where hygiene and temperature stability are critical.

Because the units are water-cooled, they are particularly advantageous in locations where ambient temperatures regularly exceed 35–40 °C, or where noise restrictions limit the use of large air-cooled condensers. They also integrate naturally into factories that already operate a central cooling-tower system for process or HVAC loads.

Why Choose a Water-Cooled Chiller – and Why EXTRUTEX

Thermodynamic and Operational Advantages

A water-cooled condenser operates against a lower heat-rejection temperature than an air-cooled condenser in the same climate. The approach temperature to the wet-bulb temperature of the cooling tower is typically smaller than the approach to the dry-bulb temperature of ambient air. Consequently, the compressor discharge pressure is lower, power consumption is reduced, and the refrigeration capacity is higher for a given compressor displacement. In practice this translates into 15–25 % lower energy consumption compared with an equivalent air-cooled unit under hot-climate conditions.

Additional benefits include quieter operation (no large condenser fans), a smaller physical footprint, and the ability to locate the chiller indoors without the need for large ventilation openings. Maintenance access is simplified because the condenser can be cleaned from the water side without outdoor work at height.

EXTRUTEX Design & Manufacturing Philosophy

EXTRUTEX brings Austrian design expertise to every product. The engineering team focuses on robustness, clear serviceability and long component life rather than on the lowest possible first cost. Critical components – compressors, expansion valves, pressure controllers and temperature sensors – are selected from internationally recognised suppliers. Manufacturing takes place in Nanjing and Shanghai facilities that operate under strict quality-management systems. This dual-location strategy provides redundancy of supply, short logistics routes for both Asian and European customers, and the ability to scale production rapidly when large projects demand multiple identical units.

Quality control includes incoming inspection of all major components, pressure testing of every refrigerant circuit, functional testing of the complete control sequence, and a final performance run under load. Documentation is supplied in English (and other languages on request) and includes wiring diagrams, P&ID schematics, recommended spare-parts lists and maintenance schedules.

After-sales support is organised through a network of local partners and direct factory service. Because the design is standardised across the SL range, spare parts are interchangeable within capacity families, reducing inventory for multi-unit installations.

Installation, Commissioning and Maintenance Guidelines

Correct installation is essential for reliable long-term operation. The chiller should be placed on a level, vibration-isolated foundation with adequate clearance for service access on all sides. Cooling-water piping to and from the cooling tower must be sized according to the flow rates listed in the specifications table and must include isolation valves, strainers and air vents. Chilled-water piping should be insulated to prevent condensation and heat gain. Electrical supply must match the nameplate voltage and frequency; a dedicated circuit breaker with correct trip characteristics is mandatory.

Commissioning typically includes leak testing of the refrigerant circuit, verification of all safety-switch set points, confirmation of correct pump rotation and flow rate, and a gradual load test while monitoring temperatures and pressures. Once stable operation is achieved, the microcomputer controller is set to the desired leaving-water temperature and the unit is handed over to production.

Routine maintenance is straightforward. Daily checks include visual inspection for leaks, verification of water-tank level, and confirmation that the leaving-water temperature is within the set-point band. Weekly tasks include cleaning of strainers and inspection of the cooling-tower circuit. Quarterly or semi-annual service includes checking refrigerant charge (via sight glass and pressure readings), cleaning the condenser water side if fouling is detected, testing all safety devices, and verifying electrical connections. With proper care, the expected service life of an EXTRUTEX SL Series chiller exceeds ten years of continuous industrial duty.

About EXTRUTEX

EXTRUTEX is an industrial equipment brand built on the foundation of Austrian design excellence and high-quality manufacturing in China. The company’s engineering roots lie in the demanding requirements of the plastics extrusion industry, where temperature control, mechanical reliability and process consistency are non-negotiable. Drawing on this heritage, EXTRUTEX has expanded its portfolio to include process-cooling solutions that serve the same customers who already rely on EXTRUTEX extruders, screws, barrels and complete extrusion lines.

Design work is performed in Austria, ensuring that every product reflects European standards of safety, documentation and ergonomics. Manufacturing is carried out in modern plants located in Nanjing and Shanghai. These facilities combine precision fabrication, rigorous quality control and the logistical advantages of China’s industrial infrastructure. The result is a product that offers European engineering character at a competitive global price point, with the flexibility to serve both large multinational projects and smaller local installations.

EXTRUTEX continues to invest in product development, focusing on energy efficiency, ease of maintenance and compatibility with modern Industry 4.0 monitoring systems. Future options will include enhanced remote-monitoring packages, alternative low-GWP refrigerants and further optimisation of heat-exchanger geometries. Customers choosing the SL Series today are investing in a platform that will remain supportable and upgradable for many years.