Volume flow controller
VRRK 500

Field of application:
The volume flow controllers VRRK are used in duct systems for automatically controlling the amount of air distribution. Their task is to maintain a predetermined target value of the air flow sustainably and independent from fluctuating duct air pressure.

Operation principles:
In constant-volume controllers without auxiliary energy, the flow control is achieved by an easy-moving, asymmetrical angled control panel that ensures a sensitive response and control behaviour even for small amounts of air flow rates.

Response and control accuracy:
The controller operates from the minimum pressure difference, which is a function of the volume flow, up to the maximum pressure difference of 1000 Pa in a stable control range. The flow rate variation over the entire pressure range is ±10 %. For smaller air speeds below 4 m/s and horizontal installation, the flow rate deviation can easily be larger than indicated above. Unfavourable flow conditions, pollution or minor bracing during installation can also cause larger deviations.

Temperature range:
The components of the controller are mostly resistant to ageing and temperature ranges from -30°C to +100°C. In volume controllers with actuators, the limiting operating temperatures of the actuators apply, which can be different depending on the type and make.

Controller structure:
The control panel is mounted in a smooth and maintenance-free PTFE bushing. One or two pneumatic piston damper prevent overshoot and oscillation of the control plate and ensure an accurate response and control behaviour.

Installation location:
The exact balancing of the control plate is ensured by a counterweight arranged vertically on the control plate, which ensures an accurate control response in all orientations. The flow profile in front of the flow controller should be cross-section-filling, since unfavourable flow conditions (such as asymmetric flow, necking, deflection around sharp edges) can negatively affect the response and control behaviour.

Setting:
The constant-volume flow controllers are shipped with either the volume flow required by the customer or with a reference flow rate set at the factory.

The volume flow can be changed at any time by the customer according to the values on the relevant scale by manual adjustment with an Allen wrench (2 mm). Optionally, the air flow can be varied by an electric or pneumatic actuator.

Dimensioning
In the selection of the controller and the dimensioning of the duct system it should be noted that the flow velocity should not be less than 3.0 m/s or higher than 10.0 m/s in the duct system. The upstream and downstream duct system to the controller should have the same dimensions. As a reference value, an average air velocity of approx. 6.5 m/s is recommended as a median and orientation value.

ATEX:
The constant-flow rate regulator can also be manufactured in an explosion-proof design according to ATEX. It can be used accordingly corresponding to the device category 2 in the gas-explosion protection zones 1 or 2, and in the dust explosion protection zones 21 and 22. The controller is characterised as follows: II 2GD c IIB 80°.

Insulation:
The flow controllers can be implemented with a sound and heat insulation in the thickness of 30 mm with an insulating shell. For construction-side insulation, the adjustment device or the actuator console can be extended. In this case, please indicate the insulation thickness when ordering.

Installation information:
According to DIN 12097, accessibility to the duct system and the volume flow controller for operation and maintenance must be observed. Please take also note of our document referring to the storage and installation instructions.

Volume flow controller  VRRK Ref. No.: 500
Constant volume flow controller automatically regulating without auxiliary energy

• Target air value according to customer specifications set at factory
• The amount of air can be changed with the adjustment device
• All height and width dimensions available; length constant
   

Volume flow controller  VRRK Ref. No.: 502
Pneumatic adjustment

Controller structure and functioning as before, factory default setting with variable control via pneumatic adjustment, controlled by a control pressure of 0.2 to 1.0 bar (maximum permitted operating pressure 1.3 bar)

Actuator type:
LTG SMA 1 or equivalent (up to width of 250 mm)
Air Torque or equivalent (from width of 251 mm)

Volume flow controller  VRRK Ref. No.: 503
Electric adjustment

Controller structure and functioning as before, factory default setting, two-set-point control via electric adjustment for an operating voltage of 230 volts, 50 Hz, as a two-set-point controller with no intermediate position, control of the set-points via switching contacts.

Actuator type:
Belimo LM 230 A-S or equivalent (up to width of 250 mm)
Belimo NM 230A-S or equivalent (from width of 251 mm)

Volume flow controller  VRRK Ref. No.: 504
Controller and operation principles analogue to 503, however, with integrated auxiliary switch for triggering an additional switching command.

Actuator type:
Belimo LM 230A-S or equivalent (up to width of 250 mm)
Belimo NM 230A-S or equivalent (from width of 251 mm)
 

Volume flow controller  VRRK Ref. No.: 505
Controller and operation principles analogue to 503, however, with an operating voltage of AC 24 V, 50/60 Hz, or DC 24 V.

Actuator type:
Belimo LM 24A or equivalent (up to width of 250 mm)
Belimo NM 24A or equivalent (from width of 251 mm)

Volume flow controller  VRRK Ref. No.: 506
Controller and operation principles analogue to 503, however, with variable control via electric adjustment for an operation voltage of AC 24 V, 50/60 Hz, or DC 24 V with control signal 2 to 10 V DC voltage.

Actuator type:
Belimo LM 24A-MF or equivalent (up to width of 250 mm)
Belimo NM 24A-MF or equivalent (from width of 251 mm)