VFC

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.

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.