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Backward Curved Centrifugal Fans

Backward Curved Centrifugal Fans Design

External rotor motors are usually contained within the depth of the fan impeller, thus saving the space normally occupied by a standard motor. They are located in the air stream, so temperature is limited, and are generally of protection class IP44, so the air needs to be clean and dry to avoid motor contamination.

Backward-curved motorised impellers develop pressure within the envelope of the impeller and do not therefore rely on a scroll housing for this purpose. They are of relatively low cost and can be simply and cheaply housed. Air is drawn through a radius inlet ring, which minimises pressure losses and air leakage, and is discharged at 90° to the inlet axis. The impeller has a ‘non-overloading’ characteristic in that it draws maximum power near the centre of its pressure/volume flow curve.

Low cost speed control is possible by supply voltage variation, either by electronic (triac) method or by transformer.


Air filtration, fume control, electronic cabinet cooling, lamp cooling, solarium equipment, roof extract units, in-line duct fans, high pressure coils, air conditioning cassettes, refrigeration equipment.

Backward Curved Centrifugal Fans

Product Range Variants


Our RRE/RRM range of high performance free running impellers begin at 133 mm up to 280mm. Fitted with EC motors with a performance range of 0,12 KW to 6.6KW, they are speed controllable and offer a constant high degree of efficiency even under partial load.

RRE – Motorised Impeller
RRM – Fan Module With Mounting Stand

Fan TypeArticle NumberVoltage (V)Frequency (Hz)Motor Power Input (kW)Rated Current (A)Fan Speed (min-1)Max Air Temperature (°C)IP Rating (IP)RRE (kg)RRM (kg)Request a Quote
RREG9192X40R or RRMG9192X40RK49-A4-1 or L38-B2-123050 / 600.141.15399050IP4X1.21.5
RREG9192X40R or RRMG9192X40RM17-A4-1 or N50-A0-111550 / 600.142.07399060IP4x1.752.05
RREG9225x63R or RRMG9225x63RK49-A6-1 or L38-B4-123050 / 600.1501.19278050IP4x1.73.0
RREG9225x63R or RRMG9225x63RM17-A6-1 or N50-A2-111550 / 600.1502.01278060IP4x1.73.0

E-Wheel Series Backward Curved Centrifugal Fans

The E-series impeller design produces significant increases in energy efficiency and major reductions in operating noise levels.  It features seven aerofoil design blades for high air flow and low to medium pressure applications such as computer room air conditioning, air handling, energy recovery units,box and roof fans.  Energy efficiency is increased by 4% and the noise level lowered by 3 to 5 dB depending on system airflow and static pressure. When combined with our EC motors, the E Series  make a very compact, efficient and optimally designed fan unit for your application. The E Wheels are made of plastic.

GKHR – Motorised Impeller (EC)
GKHM – Fan Module / Plug Type (EC)

EKHR / DKHR – Motorised Impeller (AC)
EKHM / DKHM – Fan Module (AC)

Fan TypeVoltage (V)Frequency (Hz)Input Power (kW)Rated Current (A)Speed (rpm)Max Air Temperature (°C)IP Rating (IP)Sound Power Level dB(A)Request a Quote
GKHR315-CIE.088.4EA or GKHM315-CIE.088.4EA23050 / 600.52.8220040IP5469
GKHR355-CIE.112.4EA or GKHM355-CIE.112.4EA23050 / 600.52.7165040IP5469
GKHR355-CIE.112.5FA or GKHM355-CIE.112.5FA23050 / 601.125.0225045IP5476
GKHR400-CIE.125.4FF or GKHM400-CIE.125.4FF23050 / 600.52.8138040IP5467
GKHR400-CIE.125.5FA or GKHM400-CIE.125.5FA23050 / 601.165.2187540IP5473
GKHR450-CIE.136.5FA or GKHM450-CIE.136.5FA23050 / 601.155.1155040IP5471
GKHR500-CIE.154.5HF or GKHM500-CIE.154.5HF23050 / 601.155.1133040IP5471
GKHR355-CIE.112.5FA or GKHM355-CIE.112.5FA40050 / 601.702.8260040IP5479
GKHR400-CIE.125.5HF or GKHM400-CIE.125.5HF40050 / 601.602.5210040IP5474
GKHR450-CIE.136.5HF or GKHM450-CIE.136.5HF 40050 / 601.652.7177540IP5475
GKHR450-CIE.135.6FF or GKHM450-CIE.135.6FF40050 / 603.505.1230040IP5484
GKHR500-CIE.154.5HF or GKHM500-CIE.154.5HF40050 / 601.502.4142540IP5480
GKHR500-CIE.154.6FF or GKHM500-CIE.154.6FF40050 / 602.904.4180060IP5480
GKHR560-CIE.175.6IF or GKHM560-CIE.175.6IF40050 / 603.265.0155050IP5480
EKHR315-4_E088.4EC or EKHM315-4_E088.4EC230500.1450.70137070IP5458
DKHR315-4_E088.4EC or DKHM315-4_E088.4EC400500.150.36139070IP5458
EKHR355-4_E112.5FA or EKHM355-4_E112.5FA230500.311.50140050IP5463
DKHR335-4_E112.5DF or DKHM335-4_E112.5DF400500.290.67138560IP5463
EKHR400-4_E125.5FA or EKHM400-4_E125.5FA230500.552.60139065IP5464
DKHR400-4_E125.5FA or DKHM400-4_E125.5FA400500.490.93134570IP5464
EKHR450-4_E136.6FA or EKHM450-4_E136.6FA230500.924.36141045IP5469
DKHR450-4_E136.6FA or DKHM450-4_E136.6FA400500.881.88140065IP5469
EKHR500-4_E154.6HF or EKHM500-4_E154.6HF230501.496.80138540IP5472
DKHR500-4_E154.6HF or DKHM500-4_E154.6HF400501.402.90139570IP5472
DKHR560-4_E175.6LA or DKHM560-4_E175.6LA400502.204.30133050IP5472

B-Wheel Series

The B-Wheel design can increase efficiency by up to 6% and reduce noise by three decibels compared to the standard eight-blade design. The B Wheel can offer more air at a higher pressure. Sizes range from 250 mm to 630 mm. With the enormous efficiency advantages of this series of impellers, users can easily meet ErP requirements. All B Wheels are made of aluminium.

GKHR – Motorised Impeller (EC)
GKHM – Fan Module / Plug Type (EC)

Fan TypeArticle NumberVoltage (V)Frequency (Hz)Input Power (kW)Rated Current (A)Fan Speed (min-1)Max Air Temperature (°C)IP Rating (IP)GKHR (kg)GKHM (kg)GKHB (kg)Request a Quote
GKHR630-CIB.200.6NA IE or GKHM630-CIB.200.6NA IE N86-63301 or N88-633013 Phase 400 V50 / 603.35.0118140/60IP543774
GKHR630-CIB.200.6NA IE or GKHM630-CIB.200.6NA IE N86-63302 or N88-633023 Phase 230 V50 / 603.17.7114040/60IP543774
GKHR560-CIB.180.6IF IE or GKHM560-CIB.180.6IF IEN86-56300 or N-88563003 Phase 400 V50 / 603.34.8145040/60IP543062
GKHR500-CIB.160.6IF IE or GKHM500-CIB.160.6IF IE N86-50300 or N88-503003 Phase 400 V50 / 603.65.3175040/60IP542855
GKHR400-CIB.125.6FF IE or GKHM400-CIB.125.6FF IEN86-40300 or N88-403003 Phase 400 V50 / 603.55.3260040/60IP5421.538
GKHR450.140.6IF or GKHM450.140.6IFN86-45300 or N88-453003 Phase 400 V50 / 603.65.2215040/60IP542747
GKHR355-CIB.112.6FF IE or GKHM355-CIB.112.6FF N86-35801 or N88-358013 Phase 400 V50 / 603.34.8300040/60IP542131
GKHR315-CIB.100.5FA IE or GKHM315-CIB.100.5FA IE N86-31801 or N88-31801Single Phase 230 V50 / 601.06.2240040/60IP5410.518.5
GKHR315-CIB.100.5FA IE or GKHM315-CIB.100.5FAN86-31804 or N88-318043 Phase 400 V50 / 601.62.6290040/60IP5410.518.5
GKHR280-CIB.090.5FA or GKHM280-CIB.090.5FAN86-28301 or N88-283013 Phase 400 V50 / 601.62.5350040/60IP541016
GKHR280-CIB.090.5FA IE or GKHM280-CIB.090.5FA IE N86-28303 or N88-28303Single Phase 230 V50 / 601.16.3300040/60IP541016
GKHR250-CIB.080.4EA IE or GKHM250-CIB.080.4EAN86-25300 or N88-25300Single Phase 230 V50 / 600.482.8285040/60IP545.211
GKHB 450-CEB.140.6IF-IE N88-453503 Phase 400 V505.38.3243040/60IP54 68
GKHB 500-CEB.160.6NA-IEN88-503503 Phase 400 V505.58.4200040/60IP54 68
GKHB 560-CEB.180.6NA-IEN88-563503 Phase 400 V505.27.9168040/60IP54 68
GHKB 630-CEB.200.8LAN88-633503 Phase 400 V506.69.8150040/60IP54107
GKHB 710-CEB.200.8LAN88-713523 Phase 400 V506.911.0128040/60IP54107