Application
Special features
Nominal sizes
Parts and characteristics
Construction features
Materials and surfaces
Standards and guidelines
Maintenance
Functional description
The volume flow limiter is a mechanical self-powered unit and works without external power supply. A damper blade with low-friction bearings is adjusted by aerodynamic forces such that the set volume flow rate is limited as a consequence.
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 limited.
Efficient commissioning
The volume flow limiter performs the previously tedious and expensive balancing of volume flow rates in ventilation and air conditioning systems.
Simple handling and perfect function help to save valuable working time on site. The required volume flow rate can be set at the point of installation, then the volume flow limiter is inserted into the duct. The set volume flow rate will then be limited and maintained within close tolerances.
Volume flow rate ranges
The volume flow limiters are factory set to the reference volume flow rate Vref. Customers can then simply set the required volume flow rate (setting values 1 to 11).
Nominal sizes | 80 – 250 mm |
Volume flow rate range | 4 – 212 l/s or 14 – 764 m³/h |
Volume flow rate control range | < 20 – 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 | 300 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.
VFL, Sound pressure level at differential pressure 50 Pa
80 | 4 | 14 | 30 |
80 | 6 | 22 | 30 |
80 | 14 | 50 | 32 |
80 | 20 | 73 | 33 |
80 | 23 | 82 | 34 |
100 | 5 | 18 | 31 |
100 | 11 | 39 | 33 |
100 | 16 | 58 | 35 |
100 | 26 | 92 | 36 |
100 | 34 | 122 | 37 |
125 | 11 | 39 | 36 |
125 | 19 | 69 | 37 |
125 | 27 | 98 | 37 |
125 | 42 | 150 | 38 |
125 | 54 | 195 | 39 |
150 | 14 | 50 | 32 |
150 | 29 | 105 | 32 |
150 | 44 | 160 | 33 |
150 | 57 | 205 | 33 |
150 | 74 | 265 | 34 |
160 | 16 | 58 | 26 |
160 | 28 | 102 | 29 |
160 | 49 | 175 | 32 |
160 | 67 | 242 | 34 |
160 | 90 | 323 | 36 |
200 | 26 | 94 | 23 |
200 | 70 | 253 | 27 |
200 | 109 | 391 | 30 |
200 | 134 | 481 | 31 |
200 | 147 | 529 | 31 |
250 | 44 | 159 | 23 |
250 | 94 | 337 | 26 |
250 | 144 | 519 | 28 |
250 | 175 | 632 | 28 |
250 | 212 | 764 | 28 |
Circular volume flow limiters in 7 nominal sizes, made of high-quality plastic, to limit and control volume flows in air conditioning systems.
Ready-to-commission unit which consists of the casing with setpoint scale and the control mechanism with leaf spring and low-friction, silicone-free bellows.
Easy insertion into circular ducts to EN 1506 or EN 13180; secure fit ensured by a lip seal.
Aerodynamically tested and factory set to a reference volume flow rate. Can be subsequently accurately adjusted within a volume flow rate range of at least 5 : 1.
Special features
Materials and surfaces
Technical data
Sizing data
Air-regenerated noise
Life cycle assessment
A life cycle assessment is available for the product series in form of an Environmental Product Declaration (EPD) that has been checked and published by a programme holder.
Order example: VFL/100
Nominal size | 100 mm |
Installation and commissioning
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.
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 %)
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
Construction
Galvanised sheet steel
Powder-coated surface (P1)
Stainless steel (A2)
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Ние сме тук за Вас
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Тел.: +359 2 981 25 74 | Факс: +359 2 986 20 65
За контакти
Благодарим Ви за Вашето съобщение!
Вашето съобщение е изпратено и ще бъде обработено в кратък срок.
Нашият отдел за Обслужване-Искания ще се свърже с Вас възможно най-скоро.
За общи въпроси относно продукти или услуги можете да се свържете също с:
Тел.: +359 2 981 25 74 | Факс: +359 2 986 20 65