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Östberg RKB rectangular inline duct fans, 400x200 to 800x500
Östberg (Ostberg) RKB rectangular inline duct fans for fresh-air, supply and extract ducts. Specs and spec sheets for 17 models, with installation from Chennai.
The Östberg RKB is an inline duct fan with rectangular connections, for rectangular ducting. Find your duct size in the table, then check the airflow and pressure against your duct system. Press Buy on a row to send us that model on WhatsApp, or open its spec sheet.
Ostberg RKB rectangular inline fan models and specifications
| Model | Specification sheet | Buy | Inlet / outlet mm | Supply | Power W | Current A | Speed rpm | Max flow m³/h | Max flow CFM | Max pressure Pa | Sound dB(A) at 3 m | Weight kg | IP | Max air °C |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| RKB 400x200 A1 | Spec sheet PDF | Buy | 400 x 200 | 230 V 1~ | 115 | 0.5 | 2,530 | 886 | 521 | 388 | 54 | 9.8 | 44 | 75 |
| RKB 400x200 E1 | Spec sheet PDF | Buy | 400 x 200 | 230 V 1~ | 207 | 0.91 | 2,400 | 1,465 | 862 | 596 | 56 | 10.8 | 44 | 65 |
| RKB 500x250 E1 | Spec sheet PDF | Buy | 500 x 250 | 230 V 1~ | 315 | 1.37 | 2,400 | 1,728 | 1,017 | 676 | 58 | 15.2 | 44 | 40 |
| RKB 600x300 A1 | Spec sheet PDF | Buy | 600 x 300 | 230 V 1~ | 287 | 1.3 | 920 | 2,585 | 1,521 | 278 | 50 | 32.8 | 44 | 65 |
| RKB 600x300 B1 | Spec sheet PDF | Buy | 600 x 300 | 230 V 1~ | 318 | 1.46 | 1,300 | 2,837 | 1,670 | 408 | 52 | 25.8 | 44 | 75 |
| RKB 600x300 G1 | Spec sheet PDF | Buy | 600 x 300 | 230 V 1~ | 409 | 2.1 | 1,410 | 2,912 | 1,714 | 414 | 57 | 29.1 | 54 | 45 |
| RKB 600x350 A1 | Spec sheet PDF | Buy | 600 x 350 | 230 V 1~ | 298 | 1.34 | 920 | 3,222 | 1,896 | 280 | 49 | 33.9 | 54 | 60 |
| RKB 600x350 B1 | Spec sheet PDF | Buy | 600 x 350 | 230 V 1~ | 412 | 2.11 | 1,400 | 2,992 | 1,761 | 415 | 57 | 31.8 | 54 | 45 |
| RKB 600x350 B3 | Spec sheet PDF | Buy | 600 x 350 | 400 V 3~ | 338 | 1.04 | 1,410 | 3,002 | 1,767 | 427 | 53 | 31.9 | 54 | 75 |
| RKB 600x350 D1 | Spec sheet PDF | Buy | 600 x 350 | 230 V 1~ | 515 | 2.46 | 1,370 | 3,906 | 2,299 | 491 | 55 | 33 | 54 | 45 |
| RKB 600x350 D3 | Spec sheet PDF | Buy | 600 x 350 | 400 V 3~ | 522 | 1.27 | 1,410 | 3,985 | 2,346 | 512 | 55 | 34.3 | 54 | 70 |
| RKB 700x400 E1 | Spec sheet PDF | Buy | 700 x 400 | 230 V 1~ | 731 | 3.3 | 1,252 | 5,299 | 3,119 | 603 | 56 | 44.0 | 54 | 50 |
| RKB 700x400 E3 | Spec sheet PDF | Buy | 700 x 400 | 400 V 3~ | 780 | 1.56 | 1,360 | 5,818 | 3,424 | 648 | 59 | 43.5 | 54 | 60 |
| RKB 800x500 B1 | Spec sheet PDF | Buy | 800 x 500 | 230 V 1~ | 867 | 4.44 | 870 | 7,913 | 4,657 | 408 | 57 | 66.2 | 54 | 55 |
| RKB 800x500 B3 | Spec sheet PDF | Buy | 800 x 500 | 400 V 3~ | 776 | 1.88 | 900 | 8,071 | 4,751 | 426 | 57 | 63.2 | 54 | 80 |
| RKB 800x500 K1 | Spec sheet PDF | Buy | 800 x 500 | 230 V 1~ | 1610 | 7.7 | 1,280 | 9,180 | 5,403 | 786 | 62 | 63.5 | 54 | 60 |
| RKB 800x500 K3 | Spec sheet PDF | Buy | 800 x 500 | 400 V 3~ | 1710 | 3.69 | 1,400 | 9,544 | 5,617 | 801 | 65 | 62.5 | 54 | 50 |
Inlet and outlet have the same rectangular opening, given as width x height in mm. Models ending in 1 are 230 V single-phase, models ending in 3 are 400 V three-phase, all 50 Hz. Figures are from Östberg product selector data sheets (2019 and 2020); max flow is at free air and max pressure at zero flow, so your working point will be lower. Always confirm for your duty point before ordering. Östberg ↗
Where RKB rectangular inline fans are used
Typical applications for a duct-mounted RKB. If your case is not listed, describe it and we will tell you honestly if RKB is the right fan.
Fresh air and supply ducts
Rectangular ducts above ceilings are standard in commercial HVAC. An RKB with flanged rectangular connections fits straight into the duct, and the swing-out design makes the impeller easy to clean.
Offices, malls, hotels and hospitals
Ducted supply and extract ventilation where airflow is higher than a round-duct fan can give. Air changes and pressure come from your HVAC consultant; we match the fan to that duty.
Plant rooms, server and electrical rooms
Ducted cooling-air supply and extract for rooms that must stay within a temperature limit.
Basements and car parks
Normal daily ventilation through ducts at roughly 6 to 10 air changes per hour. Not rated for fire smoke extract.
Restaurants, food courts and kitchens
Supply and general extract ducts. For grease-laden hood exhaust, tell us the application first.
Large grow rooms and container farms
Exhaust and intake for bigger indoor farms and container farms where the ducting is rectangular and the airflow is higher than a round-duct CK gives. For small tents and rooms see the CK indoor farming section.
Factories and workshops
General ventilation of workshops and machine rooms. Not for oil mist, flammable or corrosive fumes; use filtered extraction or explosion-proof fans such as Kruger MTD-EX.
Who we supply
HVAC and MEP contractors
Model-wise spec sheets for submittals, quotations for single fans or project quantities, and delivery and installation support in Chennai and South India.
Consultants and specifiers
Duty-point checks against the data sheets, supply options (single or three-phase) and noise data, so the fan you specify is the fan you get.
Facility and maintenance teams
Replacement of a failed fan by model number, with the data sheet to confirm size, voltage and speed.
Indoor farm and container-farm builders
Tell us the room or container size, lights and duct layout and we size the exhaust and intake fans.
Hospitals, hotels, malls and factories
Tell us the duct and the airflow and we choose the model, and can install it.
CK or RKB: which Östberg duct fan?
Choose by the shape of your duct first. CK fits round ducts and RKB fits rectangular ducts. Then check airflow and pressure against your duct system.
| Östberg CK | Östberg RKB | |
|---|---|---|
| Duct shape | Circular | Rectangular |
| Sizes in these data sheets | 100 to 315 mm round duct | 400x200 to 800x500 mm rectangular duct |
| Max flow at free air | 223 to 1,555 m³/h | 886 to 9,544 m³/h |
| Max pressure | 300 to 720 Pa | 278 to 801 Pa |
| Supply | 230 V single-phase | 230 V single-phase or 400 V three-phase |
| Weight | 2.5 to 6.0 kg | 9.8 to 66.2 kg |
| Choose it when | You have round ducting, small to medium airflow, toilet, kitchen or fresh-air duct | You have rectangular ducting, larger airflow, or a plant room or ceiling void |
Features
- Rectangular connections
- Backward-curved impeller
- External rotor motor with maintenance-free sealed ball bearings
- Integrated motor protection
- Galvanised sheet steel housing
- Swing-out design to simplify maintenance and cleaning of the impeller
- Junction box enclosure class IP 54
- Speed control with a transformer or electronic speed controller
- Installs in any position, and a duct-connected fan can be installed outside or in damp environments
Accessories
Östberg data sheets list mounting bracket kits, flexible connections, silencers, and transformer or electronic speed controllers. Ask us for the ones that fit your model.
How to choose an RKB
- Start with the duct size: 400x200, 500x250, 600x300, 600x350, 700x400 or 800x500 mm.
- Work out airflow: room volume x air changes per hour, then convert to m³/h or CFM (1 CFM = 1.7 m³/h).
- Add the pressure loss of the duct, bends and grilles.
- Pick the variant that can deliver that airflow at that pressure.
- Choose single-phase (1) or three-phase (3) to suit your supply, then check noise and air temperature.
Try the blower selector or send us the details on WhatsApp.
What to tell us
- Duct size and duct length
- Airflow needed, in m³/h, CFM or l/s
- Number of bends, grilles and filters
- Single-phase or three-phase supply, and whether you want speed control
- Where it is installed: indoors, outdoors, damp or hot
- Whether you need installation
Related
Östberg CK inline duct fans · All in-line duct fans · Explosion-proof mixed flow fans (Kruger MTD-EX) · Ventilation for factories, kitchens, hospitals and homes · Östberg in Chennai · Exhaust or intake: what does your room need?
Östberg is a trademark of its owner. Engineered Solutions supplies these products and is not the manufacturer.
Frequently asked questions
What is an Östberg RKB duct fan?
The Östberg RKB (also written Ostberg RKB) is an inline duct fan with rectangular connections, with a backward-curved impeller and an external rotor motor with sealed ball bearings. It has a swing-out design that makes it easier to maintain and clean the impeller, and is made to be installed in a duct system.
What is a rectangular inline duct fan used for?
It moves air through rectangular ductwork, which is common in commercial buildings. Typical uses are fresh-air and supply ducts, extract ducts, boosting airflow in long duct runs, and ventilating plant rooms, server rooms, basements and workshops.
Is an RKB the same as a cabinet inline fan?
Some sellers list RKB fans as cabinet inline fans. It is a rectangular, flanged, inline duct fan in a galvanised steel casing, fitted into rectangular ducting.
Which RKB sizes can you supply?
The data sheets we have cover connection sizes 400x200, 500x250, 600x300, 600x350, 700x400 and 800x500 mm, in several motor variants. Send us the duct size and airflow and we will confirm the model.
What do the letters and numbers in a model like RKB 600x350 B1 mean?
600x350 is the connection size in mm. The letter is the motor variant for that size. In the data sheets, models ending in 1 run on 230 V single-phase and models ending in 3 on 400 V three-phase. For example, RKB 600x350 B1 is 412 W at 230 V, and RKB 600x350 B3 is 338 W at 400 V.
Single-phase or three-phase: which RKB do I need?
It depends on the supply available at the site. The 1 models use 230 V single-phase, the 3 models use 400 V three-phase. Three-phase models in the data sheets draw less current for similar duty, for example 1.04 A for RKB 600x350 B3 against 2.11 A for RKB 600x350 B1, but the duty is not identical, so check the table.
What do max flow and max pressure mean in the table?
They are the two ends of the fan curve: the flow with no resistance and the pressure at which flow falls to zero. A fan cannot deliver both at once. Real airflow depends on the resistance of your duct, bends, grilles and filters, so send us the duty point if you know it.
Can RKB be used for a large grow room or container farm?
Yes, as exhaust or intake fans on rectangular ducts when you need more airflow than a round-duct CK. A closed container usually needs both an exhaust and a powered intake. RKB suits clean, humid air; it is not made for ammonia, corrosive or flammable gases. Tell us the room or container size and we will size the fans.
Can RKB be used for basement or car park ventilation, or smoke extract?
RKB suits daily ventilation of clean air at temperatures up to 40 to 80 °C depending on the model. It is not rated for fire smoke extract. For smoke extract, jet-fan or fire-rated systems are specified by the fire consultant, and we can point you to suitable fans. Normal basement ventilation guidance is roughly 6 to 10 air changes per hour.
Can an RKB fan be used outdoors or in a damp place?
The data sheets state that a duct-connected fan can be installed outside or in damp environments, in any position. Enclosure class is IP 44 or IP 54 depending on the model, as shown in the table. Tell us about rain, dust or fumes so we can check the application.
Can the speed of an RKB fan be controlled?
Yes. The data sheets say a transformer or electronic speed controller can be connected, and that motor protection is integrated. Accessories listed in the data sheets include mounting brackets, flexible connections, silencers and transformer controllers.
How do I get a price for an Östberg RKB fan in Chennai?
Press Buy on the model's row to send us a WhatsApp message, or tell us the model and quantity. We reply with a quotation. We are based in Chennai and handle enquiries from Tamil Nadu, Kerala, Karnataka and Andhra Pradesh, and from elsewhere in India on request.
Do you install RKB fans?
Yes. We handle installation as well as supply. Tell us your site details when you enquire and we will confirm the scope.