Type VFC

For low airflow velocities

Circular mechanical self-powered volume flow controllers for the control of supply air or extract air in constant air volume systems with low airflow velocities

  • Suitable for airflow velocities from 0.8 m/s
  • Very simple commissioning
  • Volume flow rate can be set using a rotary knob and a scale on the outside of the casing
  • Simple retrofit of an actuator for variable volume flows
  • Any installation orientation; maintenance-free
  • Casing air leakage to EN 1751, class C


Optional equipment and accessories

  • Secondary silencer Type CA, CS or CF for the reduction of air-regenerated noise
  • Hot water heat exchanger Type WL and electric air heater Type EL for reheating the airflow
  • Actuator for variable volume flows or for Vmin / Vmax switching

CAV controller variant VFC, with rotary knob 00132140_0


  • Application
  • Description

Application

  • Circular CAV controllers of Type VFC for the precise supply air or extract air flow control in constant air volume systems
  • Mechanical self-powered volume flow control without external power supply
  • For low airflow velocities
  • Simplified project handling with orders based on nominal size

Special features

  • Volume flow rate can be set using an external scale; no tools required
  • Simple retrofit of an actuator is possible
  • Correct operation even under unfavourable upstream or downstream conditions (1.5 D straight section required upstream)
  • Any installation orientation
  • Aerodynamic function testing of each unit on a special test rig prior to shipping

Nominal sizes

  • 80, 100, 125, 160, 200, 250

Parts and characteristics

  • Ready-to-commission controller
  • Damper blade with low-friction bearings
  • Bellows that acts as an oscillation damper
  • Leaf spring
  • Rotary knob with pointer for setting the volume flow rate
  • Lip seal

Attachments

  • Min/Max actuators: Actuators for switching between minimum and maximum volume flow rate setpoint values
  • Modulating actuators: Actuators for the stepless adjustment of volume flow rates

Useful additions

  • Secondary silencer Type CA, CS or CF
  • Heat exchanger Type WL
  • Electric air heater Type EL

Construction features

  • Circular casing
  • Spigot with lip seal, for circular connecting ducts to EN 1506 or EN 13180
  • Damper blade with low-friction bearings and special bellows

Materials and surfaces

  • Casing made of galvanised sheet steel
  • Damper blade and other parts made of high-quality plastic, to UL 94, V1; to DIN 4102, material classification B2
  • Leaf spring made of stainless steel
  • Polyurethane bellows

Standards and guidelines

  • Hygiene conforms to VDI 6022
  • Casing air leakage to EN 1751, class C

Maintenance

  • Maintenance-free as construction and materials are not subject to wear

Technical information

Function, Technical data, Quick sizing, Specification text, Order code, Produktbeziehungen

  • Function
  • Technical data
  • Quick sizing
  • Specification text
  • Order code
Schematic illustration of the VFC 00132975_0
① Damper blade
② Leaf spring
③ Volume flow rate scale
④ Rotary knob locking screw
⑤ Rotary knob
⑥ Lip seal
⑦ Diagram with setting values
⑧ Bellows inlet


Functional description

The volume flow controllers work without an external power supply.

A damper blade with low-friction bearings is adjusted by aerodynamic forces such that a set volume flow rate is maintained within the differential pressure range.

The aerodynamic forces of the airflow create a closing torque on the damper blade.

The bellows extends and increases this force while at the same time acting as an oscillation damper.

The closing force is countered by a leaf spring. As the differential pressure changes, the leaf spring adjusts the position of the damper blade such that the volume flow rate is maintained almost exactly.

Efficient commissioning

The volume flow rate setpoint value can be set quickly and easily using the pointer on the external scale; no measurements are required.

The advantage over flow adjustment dampers is that there is no need for repeat measurements or adjustments by an air conditioning engineer. Should the system pressure change, e.g. by opening or closing of duct sections, the flow rates in the entire system will also change if flow adjustment dampers are used; however, this is not the case with mechanical self-powered volume flow controllers A mechanical self-powered controller reacts immediately and adjusts the damper blade such that the set constant volume flow rate is maintained.

Nominal sizes

80 – 250 mm

Volume flow rate range

6 – 370 l/s or 22 – 1332 m³/h

Volume flow rate control range

Approx. 10 to 100 % of the nominal volume flow rate

Volume flow rate accuracy

approx. ± 10 % of the nominal volume flow rate

Minimum differential pressure

30 Pa

Maximum differential pressure

500 Pa

Operating temperature

10 – 50 °C


Quick sizing tables provide a good overview of the room sound pressure levels that can be expected. Approximate intermediate values can be interpolated. Precise intermediate values and spectral data can be calculated with our Easy Product Finder design programme.

The first selection criteria for the nominal size are the actual volume flow rates Vmin and Vmax. The quick sizing tables are based on generally accepted attenuation levels. If the sound pressure level exceeds the required level, a larger air terminal unit and/or a silencer is required.

VFC, Sound pressure level at differential pressure 50 Pa

Nominal size V Air-regenerated noise Case-radiated noise
Nominal size V
Nominal size V LPA LPA1 LPA2
Nominal size l/s m³/h dB(A)

80

6

22

25

<15

<15

<15

<15

80

10

36

28

16

<15

<15

<15

80

20

72

33

21

<15

<15

<15

80

42

151

39

27

18

16

17

100

6

22

29

15

<15

<15

<15

100

15

54

33

20

<15

<15

15

100

30

108

37

26

18

17

18

100

65

234

41

33

26

25

21

125

10

36

22

<15

<15

<15

<15

125

20

72

27

16

<15

<15

<15

125

45

162

34

25

18

16

<15

125

100

360

41

34

29

27

16

160

18

65

25

16

<15

<15

<15

160

45

162

32

24

18

16

18

160

85

306

36

29

24

22

22

160

185

666

41

35

30

28

27

200

25

90

27

16

<15

<15

<15

200

60

216

31

22

16

<15

18

200

120

432

35

27

21

19

22

200

250

900

37

30

25

24

26

250

37

133

31

21

<15

<15

18

250

100

360

35

25

18

16

22

250

185

666

36

28

21

19

25

250

370

1332

37

29

23

22

29

① VFC

② VFC with secondary silencer CS/CF, insulation thickness 50 mm, length 500 mm

③ VFC with secondary silencer CS/CF, insulation thickness 50 mm, length 1000 mm

④ VFC with secondary silencer CS/CF, insulation thickness 50 mm, length 1500 mm


Circular volume flow controllers for constant and variable air volume systems with low airflow velocities, mechanical self-powered, without external power supply, suitable for supply or extract air, available in 6 nominal sizes.

Ready-to-commission unit consists of the casing containing a damper blade with low-friction bearings, bellows, leaf spring, and a rotary knob to set the volume flow rate setpoint.

Differential pressure: 30 – 500 Pa

Volume flow rate: max. 10 : 1

Spigot with lip seal, for circular connecting ducts to EN 1506 or EN 13180.

Casing air leakage to EN 1751, class C.

Special features

  • Volume flow rate can be set using an external scale; no tools required
  • Simple retrofit of an actuator is possible
  • Correct operation even under unfavourable upstream or downstream conditions (1.5 D straight section required upstream)
  • Any installation orientation
  • Aerodynamic function testing of each unit on a special test rig prior to shipping

Materials and surfaces

  • Casing made of galvanised sheet steel
  • Damper blade and other parts made of high-quality plastic, to UL 94, V1; to DIN 4102, material classification B2
  • Leaf spring made of stainless steel
  • Polyurethane bellows

Technical data

  • Nominal sizes: 80 to 250 mm
  • Volume flow rate range: 6 to 370 l/s or 22 to 1332 m³/h
  • Volume flow rate control range: approx. 10 – 100 % of the nominal volume flow rate
  • Volume flow rate accuracy: approx. ± 10 % of the nominal volume flow rate
  • Minimum differential pressure: 30 Pa
  • Maximum differential pressure: 500 Pa

Sizing data

  • V _______________________ [m³/h]
  • Δpst _______________________ [Pa]

Air-regenerated noise

  • LPA _______________________ [dB(A)]

Case-radiated noise

  • LPA _______________________ [dB(A)]

This specification text describes the general properties of the product. Texts for variants can be generated with our Easy Product Finder design programme.

00131326_0

 Type
VFC       Volume flow controller

 

 Nominal size [mm]
80
100
125
160
200
250

 Actuator
       No entry: manual operation
       For example
E01       24 V AC/DC, 3-point, potentiometer
E03       24 V AC/DC, modulating 2 – 10 V DC, potentiometer
M01       24 V AC/DC, 3-point, mechanical stops

Order example: VFC/100/E03

Nominal size

100 mm

Actuator

Variable volume flow, 24 V AC/DC, potentiometer, control signal 0 to 10 V DC


 

Variants, Attachments, Dimensions and weight, Product details

  • Variants
  • Attachments
  • Dimensions and weight
  • Product details

VFC, actuators

Order code detail Actuator Supply voltage Auxiliary switch

Min/Max actuators




E01

Actuator with potentiometers TROX/Gruner

24 V AC/DC

E02

Actuator with potentiometers TROX/Gruner

230 V AC

M01

Actuator with mechanical stops TROX/Belimo

24 V AC/DC

M02

Actuator with mechanical stops TROX/Belimo

230 V AC

Modulating actuators




E03

Actuator with potentiometers TROX/Gruner

24 V AC/DC


Nominal size
VFC
m
kg
VFC/.../E0*
m
kg
VFC/.../M0*
m
kg
ØD
mm
80 0.5 0.8 0.7 79
100 0.6 0.9 0.8 99
125 0.7 1.0 0.9 124
160 0.8 1.1 1.0 159
200 1.0 1.3 1.2 199
250 1.3 1.6 1.5 249



VFC system 00137034_0
① CAV controller with rotary knob
② Actuator E0* with potentiometers
③ Actuator M0* with mechanical stops


Installation details, Basic information and nomenclature

  • Installation details
  • Basic information and nomenclature

Installation and commissioning

  • Any installation orientation
  • Take the adjustment value from the characteristic on the sticker (on each volume flow controller)
  • Volume flow rate setpoint can be set on external scale

Upstream conditions

The volume flow rate accuracy ΔV applies to a straight upstream section of the duct. Bends, junctions or a narrowing or widening of the duct cause turbulence that may affect measurement. Duct connections, e.g. branches off the main duct, must comply with EN 1505. Some installation situations require straight duct sections upstream.

Free air intake only with a straight duct section of 1D upstream.

Space required for commissioning and maintenance

Sufficient space must be kept clear near any attachments to allow for commissioning and maintenance. It may be necessary to provide sufficiently sized inspection access openings.

Space required

Attachments
Attachments mm

Without actuator

200

200

200

With actuator E0*

200

200

300

With actuator M0*

200

200

230


Prinipal dimensions

ØD [mm]

Outside diameter of the spigot

ØD₁ [mm]

Pitch circle diameter of flanges

ØD₂ [mm]

Outside diameter of flanges

ØD₄ [mm]

Inside diameter of the screw holes of flanges

L [mm]

Length of unit including connecting spigot

L₁ [mm]

Length of casing or acoustic cladding

B [mm]

Duct width

B₁ [mm]

Screw hole pitch of flange (horizontal)

B₂ [mm]

Outside dimension of flange (width)

B₃ [mm]

Width of device

H [mm]

Duct height

H₁ [mm]

Screw hole pitch of flange (vertical)

H₂ [mm]

Outside dimension of flange (height)

H₃ [mm]

Unit height

n [ ]

Number of flange screw holes

T [mm]

Flange thickness

m [kg]

Unit weight including the minimum required attachments for manual adjustment

Acoustic data

fm [Hz]

Octave band centre frequency

LPA [dB(A)]

A-weighted sound pressure level of air-regenerated noise of the VAV terminal unit, system attenuation taken into account

LPA1 [dB(A)]

A-weighted sound pressure level of air-regenerated noise of the VAV terminal unit with secondary silencer, system attenuation taken into account

LPA2 [dB(A)]

A-weighted sound pressure level of case-regenerated noise of the VAV terminal unit, system attenuation taken into account

LPA3 [dB(A)]

A-weighted sound pressure level of case-regenerated noise of the VAV terminal unit with acoustic cladding, system attenuation taken into account


All sound pressure levels are based on 20 μPa.

Volume flow rates

Vnom [m³/h] and [l/s]

Nominal volume flow rate (100 %)

  • The value depends on product type and nominal size
  • Values are published on the internet and in technical leaflets, and stored in the Easy Product Finder design software.
  • Upper limit of the setting range and maximum volume flow rate setpoint value for the CAV controller

V [m³/h] and [l/s]

Volume flow rate

ΔV [± %]

Volume flow rate tolerance from setpoint value

Differential pressure

Δpst [Pa]

Static differential pressure

Δpst min [Pa]

Static differential pressure, minimum

  • The static minimum differential pressure is equal to the pressure loss of the CAV controller when the damper blade is open, caused by flow resistance (bellows, crossbar)
  • If the pressure on the CAV controller is too low, the setpoint volume flow rate may not be achieved, not even when the damper blade is open
  • Important factor in designing the ductwork and in rating the fan including speed control
  • Sufficient duct pressure must be ensured for all operating conditions and for all controllers, and the measurement point or points for speed control must have been selected accordingly to achieve this

Construction

Galvanised sheet steel

  • Casing made of galvanised sheet steel
  • Parts in contact with the airflow as described for the product type
  • External parts, e.g. mounting brackets or covers, are usually made of galvanised sheet steel

Powder-coated surface (P1)

  • Casing made of galvanised sheet steel, powder-coated RAL 7001, silver grey
  • Parts in contact with the airflow are powder-coated or made of plastic
  • Due to production, some parts that come into contact with the airflow may be stainless steel or aluminium, powder-coated
  • External parts, e.g. mounting brackets or covers, are usually made of galvanised sheet steel

Stainless steel (A2)

  • Casing made of stainless steel 1.4201
  • Parts in contact with the airflow are powder-coated or made of stainless steel
  • External parts, e.g. mounting brackets or covers, are usually made of galvanised sheet steel

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