Finder 7F.21.9.024.4250.0 – 7F Series Filter Fans – Reverse flow – Black version

Why Choose the Finder 7F.21.9.024.4250.0 Black Reverse Flow Filter Fan?

The Finder 7F.21.9.024.4250.0 is a high-performance 24 V DC reverse flow filter fan designed for extracting warm air from industrial electrical cabinets, automation control panels and machinery enclosures. Part of the Finder 7F Series, this Size 4 industrial ventilation fan combines a nominal 250 m³/h free-air airflow, low-voltage DC operation and a distinctive black RAL 9004 housing for reliable electrical enclosure thermal management.

Unlike conventional intake filter fans, the Finder 7F.21 reverse flow configuration moves air from inside the enclosure to the surrounding environment. This allows the fan to function as a powered exhaust outlet, helping remove heat generated by variable frequency drives, industrial power supplies, transformers, contactors and other electrical equipment. When combined with a correctly positioned filtered air inlet, it can form part of an effective forced-air cabinet cooling system.

Operating from a 24 V DC supply, the Finder 7F.21.9.024.4250.0 features a 43 W rated power consumption, a Size 4 (10-inch class) mounting format and UL Type 12 enclosure protection when installed in accordance with the manufacturer's requirements. The black finish distinguishes this model from the standard grey Finder 7F.21.9.024.4250, making it particularly suitable for dark-coloured electrical cabinets and specialist industrial machinery.

Key Advantages

• 250 m³/h nominal free-air airflow provides effective ventilation for industrial electrical enclosures.
• Approximately 147 CFM airflow capacity supports medium and large cabinet cooling applications.
• Reverse flow exhaust operation actively removes heated air from inside electrical cabinets.
• 24 V DC operating voltage integrates with compatible industrial automation power systems.
• 43 W rated power consumption supports high-volume DC fan operation.
• Black RAL 9004 housing complements dark-coloured electrical cabinets and custom machinery enclosures.
• Size 4 construction provides a standardised format for industrial cabinet ventilation.
• UL Type 12 protection classification supports suitable indoor industrial installations.
• IP54 protection helps maintain enclosure resistance to dust and splashing water when correctly installed.
• Replaceable filter mat allows straightforward servicing and maintenance.
• Snap-in mounting arrangement helps reduce installation time.
• Push-in electrical terminals support efficient connection to the DC power supply.
• High-airflow enclosure ventilation helps reduce temperature build-up around electrical equipment.
• Compatible with Finder Size 4 ventilation accessories for planned cabinet cooling arrangements.
• Suitable for industrial automation, electrical distribution and machinery control systems.
• Black finish option provides a colour-matched alternative to the standard grey version without changing the fundamental airflow configuration.

Key Features

• Finder 7F Series industrial enclosure ventilation fan.
• Type 7F.21 reverse flow filter fan.
• Exact manufacturer part number: 7F.21.9.024.4250.0.
• Black RAL 9004 housing and grille.
• Reverse flow / exhaust airflow configuration.
• 24 V DC nominal supply voltage.
• 250 m³/h nominal free-air airflow.
• Approximately 147 CFM free-air rating.
• 43 W rated power.
• Approximately 1.8 A nominal current consumption.
• Size 4 industrial fan and filter assembly.
• 10-inch class enclosure ventilation format.
• 255 × 255 mm front grille dimensions.
• 223 × 223 mm nominal enclosure cut-out.
• Approximately 104.2 mm overall assembly depth.
• IP54 protection rating when correctly installed.
• UL Type 12 enclosure protection classification.
• Replaceable filter media.
• Snap-in panel mounting.
• Push-in electrical connections.
• Designed for indoor industrial electrical enclosures.
• Compatible with appropriately designed filtered air inlet arrangements.

High-Performance Reverse Flow Cooling for Electrical Cabinets

The Finder 7F.21.9.024.4250.0 provides forced-air exhaust ventilation for electrical enclosures containing equipment that generates heat during normal operation. Industrial components such as variable frequency drives, transformers, power supplies, motor starters and electronic controllers can increase internal cabinet temperatures, particularly where the enclosure has limited natural ventilation.

The fan's reverse flow design addresses this problem by extracting air from inside the enclosure. Warm air is discharged through the fan assembly, while replacement air enters through a suitable opening elsewhere in the cabinet.

With a nominal 250 m³/h free-air airflow, the Finder 7F.21.9.024.4250.0 is designed for installations requiring substantial air exchange. Its airflow capacity is approximately 147 CFM, making it suitable for a wide range of industrial automation and electrical distribution applications.

The free-air rating represents fan performance under specified low-resistance conditions. Actual installed airflow will normally be lower because filters, enclosure openings, internal equipment and airflow paths create resistance.

When used with a corresponding filtered ventilation arrangement, the available airflow may be approximately 195 m³/h, depending on the system configuration. This illustrates why cabinet ventilation should be designed using realistic operating conditions rather than relying on the free-air rating alone.

For effective cooling, the fan should be paired with a suitable filtered air inlet. The inlet and exhaust positions should encourage airflow across heat-generating components instead of allowing incoming air to pass directly to the exhaust opening.

Black RAL 9004 Housing for Specialist Industrial Enclosures

A distinguishing feature of the Finder 7F.21.9.024.4250.0 is its black RAL 9004 housing. This makes the fan particularly suitable for electrical cabinets where a black or dark-coloured finish is preferred.

Black electrical enclosures are commonly used in specialist industrial machinery, OEM equipment, custom automation installations and coordinated electrical panel designs. Selecting a matching black filter fan helps maintain a consistent appearance across the cabinet.

The final .0 suffix is important when identifying the correct product variant. In the Finder 7F.2x range, this suffix specifies the black RAL 9004 version, while the corresponding model without the suffix is supplied in the standard grey RAL 7035 finish.

For example, the Finder 7F.21.9.024.4250 and Finder 7F.21.9.024.4250.0 have the same fundamental fan configuration, supply voltage and nominal airflow class. The key difference is the housing colour.

When ordering a replacement, the full manufacturer part number should be checked to ensure the correct voltage, airflow direction, size and finish are selected.

24 V DC Operation for Industrial Automation Systems

The Finder 7F.21.9.024.4250.0 operates from a nominal 24 V DC supply, making it suitable for industrial control panels that use low-voltage DC power distribution.

Its 43 W rated power consumption corresponds to approximately 1.8 A at the nominal supply voltage. The DC power supply should be selected with sufficient capacity for the fan and all other connected equipment.

The fan may be incorporated into a temperature-controlled ventilation arrangement using a suitably rated thermostat, controller or switching device. This allows ventilation to operate according to the thermal requirements of the electrical enclosure.

For example, a cabinet thermostat can be configured to energise the fan when the internal temperature rises above a selected threshold. This can help avoid unnecessary fan operation during periods when forced ventilation is not required.

This is a DC-powered product. It must not be connected directly to a 120 V AC or 230 V AC supply. Where an AC-powered filter fan is required, an appropriately rated Finder 7F Series AC model should be selected instead.

Replaceable Filter Mat and Reduced Maintenance Time

The Finder 7F.21.9.024.4250.0 incorporates a replaceable filter mat as part of its industrial enclosure ventilation assembly. The filter helps manage airborne contaminants in the ventilation path and supports the protection of electrical equipment.

Filter condition is important because accumulated dust increases airflow resistance. If the filter becomes heavily contaminated, ventilation performance may decrease, potentially allowing the enclosure temperature to rise.

Regular inspection and replacement of the filter mat should therefore form part of routine electrical cabinet maintenance. The appropriate service interval depends on the surrounding environment, dust concentration and operating conditions.

The corresponding Size 4 replacement filter mat is the Finder 07F.45. The correct filter material should be selected according to Finder's accessory documentation to maintain the intended fit and filtration performance.

The fan's modular construction and snap-in mounting arrangement are designed to simplify installation and servicing. Maintenance should only be carried out after following the relevant electrical isolation and safe working procedures.

Size 4 Snap-In Installation and Industrial Enclosure Protection

The Finder 7F.21.9.024.4250.0 uses a Size 4 mounting format with a front grille measuring approximately 255 × 255 mm.

The fan is designed for a nominal 223 × 223 mm enclosure cut-out, with the relevant mounting tolerance specified in Finder's installation documentation. Before cutting the enclosure panel, the installer should check the manufacturer's current dimensional drawing.

The snap-in mounting system helps reduce installation time and supports integration into suitable electrical cabinet sidewalls or other manufacturer-approved panel positions.

The fan also features push-in electrical connections, allowing efficient wiring to the appropriate 24 V DC supply.

When correctly installed, the fan provides IP54 protection and is specified for UL Type 12 indoor industrial enclosure applications. These protection characteristics depend on correct installation and the overall enclosure design.

The fan should not be assumed suitable for outdoor exposure, aggressive chemicals or unusually high ambient temperatures without checking the manufacturer's environmental specifications.

Reliable Thermal Management for Industrial Equipment

Effective electrical enclosure ventilation helps protect equipment against excessive operating temperatures. By extracting warm air, the Finder 7F.21.9.024.4250.0 can support more stable operating conditions for automation components and electrical distribution equipment.

However, forced-air ventilation depends on the surrounding ambient temperature. A filter fan cannot cool an enclosure below the temperature of the incoming air. If the ambient air is too warm, or the enclosure must remain sealed against contaminants, an enclosure air conditioner or another cooling system may be necessary.

Correct fan selection should consider the total heat dissipated by the installed equipment, the permitted internal cabinet temperature, the surrounding ambient temperature and the airflow resistance of the complete ventilation arrangement.

The Finder 7F.21.9.024.4250.0 is therefore best used as part of a properly designed industrial thermal management system rather than as a standalone guarantee of enclosure temperature control.

Typical Applications

• Industrial electrical cabinet exhaust ventilation.
• Black and dark-coloured automation control panels.
• 24 V DC industrial control system enclosures.
• PLC and industrial automation cabinets.
• Variable frequency drive and motor control panels.
• Electrical distribution and switchboard enclosures.
• Industrial machinery electrical cabinets.
• Manufacturing and production line control systems.
• Industrial power supply and transformer enclosures.
• Packaging and processing machinery.
• Machine tool electrical panels.
• Industrial OEM electrical cabinet manufacturing.
• Custom-built machinery and specialist equipment enclosures.
• Electrical cabinet refurbishment and maintenance.
• Applications requiring a black reverse flow exhaust filter fan.
• Low-voltage DC cabinet thermal management systems.