Application
Special features
Nominal sizes
Construction features
Materials and surfaces
Powder-coated construction (P1)
Stainless steel construction (A2)
Functional description
The volume flow controller 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 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 that unrolls over a cam plate. The shape of the cam plate is such that a change in the differential pressure leads to an adjustment of the damper blade in a way 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.
Volume flow rate ranges
The minimum differential pressure of CAV controllers is an 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 control units. The measurement points for fan speed control must be selected accordingly.
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.
Sizing example
Given data
Vmax = 280 l/s (1010 m3/h)
Δpst = 150 Pa
Required sound pressure level in the room 35 dB(A)
Quick sizing
RN/200 with circular silencer CS 050/200×1000
Air-regenerated noise LPA = 26 dB(A)
Case-radiated noise LPA = 31 dB(A)
Circular volume flow controllers for constant air volume systems, mechanical self-powered, without external power supply, suitable for supply or extract air, available in 8 nominal sizes.
Ready-to-commission unit consists of the casing containing a damper blade with low-friction bearings, bellows, external cam plate and leaf spring.
Volume flow controllers without actuators are factory set to a reference volume flow rate (customers can set the required volume flow rate on site).
Spigot with groove for lip seal, suitable for connecting ducts according to EN 1506 or EN 13180.
Casing air leakage to EN 1751, class C.
Special features
Materials and surfaces
Galvanised sheet steel construction
Powder-coated construction (P1)
Stainless steel construction (A2)
Variant with acoustic cladding (-D)
Mineral wool
Construction
Technical data
Sizing data
Air-regenerated noise
Case-radiated noise
This specification text describes the general properties of the product. Texts for variants can be generated with our Easy Product Finder design programme.
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