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Inline centrifugal fan in heat- and sound-insulated casing with air flow up to 1515 m³/h.

  • Description
  • Characteristics
  • Capacity diagram
  • Downloads
  • Dimensions
  • Additional diagrams
  • Designation key
  • The design of the KSB fans allows to use them in supply and exhaust ventilation systems for commercial, office and other public or industrial premises with high requirements to the noise level, efficiency and fan control and with limited space for mounting.
  • For example, the unit design includes a possibility of space-restricted installation above suspended ceilings.
  • They are designed for mounting into Ø 100-500 mm air ducts.
  • The fan casing is made of aluzinc.
  • For easy installation and operation, the top cover of the fan is secured with a special lock.
  • Warm and sound insulation is made of non-combustible mineral wool 50 mm thick.
  • To ensure better noise absorption, the inner surface of the insulation is made of a perforated metal sheet.
  • The round connecting spigots are rubber sealed.
  • The fans are equipped with asynchronous motors with an external rotor and centrifugal impellers with backward curved blades.
  • The motors are equipped with an integrated overheating protection with automatic restart.
  • The use of ball bearings with specially selected lubricating oil guarantees low noise and makes the fan completely maintenance-free.
  • Inline fans are designed for round air ducts.
  • The fans are installed at an air duct junction.
  • The use of flexible connectors requires  fixation of the fan on the building structure by means of supports, mounts, or fixing brackets.
  • The fan can be fixed in any position, taking into account the air flow direction indicated by the arrow on the fan casing.
  • While mounting the fan provide enough access for servicing and repair operations.
  • The control can be either smooth or stepped and carried out with a thyristor or autotransformer regulator.
  • Several fans can be connected to one controller, provided that the total power and operating current do not exceed the nominal parameters of the controller. 
Parameter KSB 250 K2
Measurement unit
Highpowered motor Highpowered motor no -
Low-powered motor no -
Phase 1 ˜
Voltage 230 V
Frequency 50 Hz
Sound pressure level at 3 m distance 45 dBА
Power consumption 320 W
Maximum air capacity 1515 m³/h
Current 1.40 A
RPM 2615 min-1
Max. transported air temperature -25...+55 °С
Protection rating IP X4 -
Duct diameter 250 mm
Weight 33 kg
Design centrifugal -
Sound- and heat-insulated casing yes -
Casing material aluzinc -
SEC Class - -
Duct for round air ducts -
Type supply and exhaust -
Mounting Inline -
Capacity diagram
Capacity diagram
  • Selection method:
  • Air flow:
  • Pressure:
Operating point
  • Air flow: --
  • Pressure: ---
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"VENTS KSB K2" product description 05-2022 (pdf 1.15Mb)
Download high quality image "VENTS KSB K2 (ErP 2018)" (psd 3.64Mb)
Download image "VENTS KSB K2 (ErP 2018)" for your website (png 216.13Kb)
"VENTS KSB K2" user’s manual 11-2021 (V143-1EN-02) (pdf 1.76Mb)
Parameter Value Measurement unit
∅D 248 mm
B 677 mm
B1 537 mm
H 429 mm
L 774 mm
L1 759 mm
L2 666 mm
Additional diagrams
Additional diagrams
Sound power level [dBA], A-weighted Sound pressure level at 3 m distance, A-weighted Sound pressure level at 1 m distance, A-weighted
Sound power level Gen. Octave frequency band [Hz]
  Hz 63 125 250 500 1000 2000 4000 8000 LpA, 3 m [dBA] LpA, 1 m [dBA]
LwA to inlet dbA 77 60 70 75 64 59 52 52 40 56 66
LwA to outlet dbA 81 67 77 79 74 60 52 55 46 61 71
LwA to environment dbA 65 46 60 63 55 48 33 33 34 45 55
Designation key
Designation key
Series Spigot diameter Modification Motor Options
VENTS KSB 100; 125; 150; 160; 200; 250; 315; 355; 400; 450; 500 К2: heat- and sound-insulated casing S: high-powered motor; R1: power cord with a mains plug
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Basic parameter for domestic fan selection