RITTAL SK3325024 Fan Filter Unit – TopTherm Series

RITTAL SK3325024 Fan-and-Filter Unit: Enclosure Thermal Regulation Under Continuous Industrial Load

Enclosure overheating is not a theoretical risk — it is a documented failure mode that accounts for a significant share of unplanned PLC and drive shutdowns in manufacturing environments. The RITTAL SK3325024 is a 230 V AC fan-and-filter unit engineered to maintain positive-pressure airflow through control panel enclosures, preventing heat accumulation at the component level. It is not a generic ventilation accessory. It is a precision thermal management component with defined airflow curves, certified ingress protection, and a mechanical interface designed for the RITTAL TS 8, AX, and SE enclosure families.

This page documents the SK3325024 from an engineering standpoint: its physical construction, thermal performance envelope, integration logic within a panel thermal design, and the procurement pathway for verified original units shipped from Xiamen, China.

Real-time Stock & RFQ: [email protected] | WhatsApp: +86 18359268345

Technical Parameters

Hardware Logical Analysis

The SK3325024 operates on a straightforward but carefully engineered principle: forced convection through a filtered aperture to maintain a positive-pressure differential inside the enclosure. Understanding the hardware logic behind this unit is essential for correct thermal design and long-term reliability.

Motor Technology: The SK3325024 uses an AC shaded-pole motor at 230 V / 50–60 Hz. Shaded-pole motors have no brushes, no commutator, and no start capacitor — the failure modes associated with those components are eliminated. The trade-off is lower efficiency compared to EC (electronically commutated) motors, but for a 13 W unit running in a fixed-speed, continuous-duty application, the thermal dissipation from the motor itself is negligible relative to the enclosure heat load it is managing.

Airflow Path and Pressure Curve: The 20 m³/h free-blowing rating is measured with no external resistance. In a real installation, the filter mat introduces static pressure drop — typically 10–20 Pa at rated airflow for a clean G2 mat. As the filter mat loads with particulate over time, static resistance increases and airflow decreases along the fan’s pressure-flow curve. This is the primary reason RITTAL specifies periodic filter mat inspection: a partially blocked mat can reduce effective airflow by 30–40%, silently degrading thermal performance before any alarm condition is triggered.

IP 54 Sealing Mechanism: The IP 54 rating is achieved through the combination of the fan housing geometry and the filter mat frame seal. The filter mat (SK 3329.100 standard, SK 3329.110 fine) creates a labyrinthine path that prevents direct water spray ingress while maintaining airflow. Critically, IP 54 is only valid with the filter mat correctly seated. Operating the unit without a filter mat drops protection to IP 20 or lower — an important consideration during maintenance windows in dusty or wet environments.

EMC Considerations: The SK3325024 does not incorporate active EMC suppression circuitry. The motor generates low-level conducted emissions on the supply line, consistent with Class A industrial equipment. In installations where sensitive measurement equipment shares the same distribution panel, a line filter on the fan supply circuit is advisable. RITTAL’s own SK 3301 series line filters are dimensioned for this purpose.

Thermal Derating: The unit is rated to +70 °C ambient. Above +55 °C, motor winding insulation begins to approach its thermal class limit under continuous operation. In high-ambient installations (e.g., outdoor enclosures in subtropical climates), verify that the motor’s duty cycle and ambient temperature remain within the derating curve published in the RITTAL TopTherm technical documentation.

Snap-in Mechanical Interface: The tool-free snap-in mounting system uses four spring-loaded retention clips that engage the panel cut-out edge. The 119 × 119 mm cut-out is standardised across the RITTAL TS 8, AX, and SE enclosure families, allowing the SK3325024 to be swapped without additional hardware. Panel thickness must not exceed 3 mm — thicker panels prevent full clip engagement and compromise both mechanical retention and the IP 54 seal.

System Integration Benefits

• Standardised cut-out geometry: The 119 × 119 mm panel cut-out is consistent across RITTAL TS 8, AX, and SE enclosure families, eliminating custom fabrication and reducing installation time to under five minutes per unit.
• Positive-pressure enclosure strategy: By blowing filtered air into the enclosure (rather than exhausting), the SK3325024 maintains a slight positive pressure differential that actively resists ingress of unfiltered ambient air through cable glands and door seals — a meaningful advantage in dusty production environments.
• Predictable thermal performance: The published airflow curve allows engineers to calculate enclosure temperature rise (ΔT) using the standard formula: ΔT = P / (ρ × Cp × Q), where P is internal heat dissipation in watts, ρ is air density, Cp is specific heat, and Q is volumetric airflow. This enables deterministic thermal design rather than empirical guesswork.
• Filter mat replacement without enclosure shutdown: The filter mat frame is accessible from the front face of the unit without opening the enclosure door or disconnecting power. In live panel environments, this allows maintenance personnel to inspect and replace filter mats during production without interrupting the control system.
• Compatibility with RITTAL CMC monitoring: When paired with RITTAL’s CMC III monitoring system and a temperature/humidity sensor inside the enclosure, the SK3325024 becomes part of a closed-loop thermal monitoring architecture — providing real-time visibility into enclosure climate without requiring a dedicated HVAC controller.
• Scalable airflow architecture: The SK3325024 (20 m³/h) is part of a family that includes the SK3326024 (30 m³/h) and SK3327024 (55 m³/h), all sharing the same cut-out dimensions. As enclosure heat loads increase with additional drives or I/O modules, the thermal management strategy can be upgraded by substituting a higher-airflow unit without panel rework.
• Dual-voltage ecosystem: The 230 V AC variant (SK3325024) has a direct 115 V AC counterpart (SK3325100) with identical mechanical dimensions. In facilities with mixed voltage distribution, both variants can be stocked interchangeably without maintaining separate spare part inventories for mechanical components.
• Compliance with UL 508A panel builder requirements: The SK3325024 carries UL 508A recognition, which is a prerequisite for inclusion in UL-listed industrial control panels destined for the North American market. This eliminates the need for field engineering evaluation of the ventilation component during UL panel certification.

Quality Assurance & Global Logistics

Product Authenticity: All SK3325024 units supplied through siemensplc.com are sourced from verified distribution channels. Each unit is inspected on receipt for label authenticity, housing integrity, filter mat condition, and connector completeness. Units with damaged housings, missing filter mats, or suspect labelling are rejected and not listed for sale. RITTAL’s original packaging is preserved where available.

12-Month Warranty: Every unit carries a 12-month warranty from the date of dispatch. Warranty coverage includes manufacturing defects and premature motor failure under normal operating conditions. It does not cover damage from incorrect voltage supply, filter mat neglect leading to motor overheating, or mechanical damage from improper installation.

Logistics Infrastructure — Xiamen, China: Our warehouse operates from Xiamen, Fujian Province — a primary export hub with direct access to international air freight via Xiamen Gaoqi International Airport and sea freight via Xiamen Port. This location supports rapid dispatch to all major industrial markets.

• DHL Express Worldwide: 3–5 business days to Southeast Asia, Middle East, and Europe. Full door-to-door tracking from dispatch.
• FedEx International Priority: 4–6 business days to North America (US, Canada, Mexico). Preferred carrier for time-critical shipments to the Americas.
• UPS / TNT: Available for specific destination countries or customer carrier account preferences.
• Air Freight (Forwarder): For multi-unit or pallet-quantity orders, we coordinate with licensed freight forwarders for airport-to-airport or door-to-door air freight from Xiamen.

Export Documentation Package: Commercial Invoice with accurate HS code and declared value, Packing List, Certificate of Origin (China), and MSDS where applicable. All documentation is prepared to the import requirements of the destination country to minimise customs clearance delays.

Same-day dispatch is available for orders confirmed and paid before 14:00 CST on business days. For urgent requirements, contact us directly via WhatsApp for real-time coordination: +86 18359268345.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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