Volumetric Flow Controller ATEX VRA-R-E-Ex

When using volumetric flow controllers in roof central units, in extreme cases, condensation can build up in the measuring pipes of the volumetric flow controller as a result of the large temperature differences between the air flowing through the volumetric flow controller and the surrounding air. This condensation may affect or damage the sensor. This is why for this field of application care must be taken to insulate the housings of the volumetric flow controllers and the measuring hoses (to prevent condensation) and to mount the controllers in such a way that any condensate formed on the outside of the measuring hoses can run downward and be drained (without entering the sensor).
When connecting SCHAKO components to customer installations, any compatibility problems are beyond our scope of responsibility and must be solved on-site.

Volumetric flow range: 80 - 5345 m³/h

Function:
A volumetric flow controller is used for pressure-independent volumetric flow regulation in ventilation and air-conditioning systems. It serves to keep the volumetric flow either constant within specified limits (CAV) or to control it variably (VAV).
Housing, measuring sensor, control flap, PI controller with pressure sensor and actuator form a closed control loop with feedback, allowing demand-dependent, energy-saving air conditioning of Single rooms or areas of air-conditioning systems. When suitable electrical controller types are used, room or duct pressure regulation can be achieved.
The first adjustment of the Vmin, Vmax and Vnenn operating volumetric flows is done prior to delivery ex works in accordance with customer specifications. When these values are set, the functions of all volumetric flow controllers are also checked. The maximum deviation of the volumetric flows is +/- 5 %, relative to the nominal volumetric flow Vnenn.
For measurement of the effective pressure, SCHAKO relies on a measuring principle based on Aluminium measuring rods. Using the method of centroidal axis, 6 measuring points are fixed on the pressure side and 6 measuring points on the suction side of the rods, thus determining the average values. In comparison with measuring rods or measuring orifices having fewer measuring points, this gives higher accuracy, allowing the inflow area required in front of the volumetric flow controller to be minimised.
When using the controllers in systems with heavy dust contamination, suitable filters must be used.
Since the membrane zero point must not be changed in static sensors, the mounting instructions documented by the manufacturer must be adhered to. Volumetric flow controllers of the VRA ...-Ex type are not suitable for air containing sticky and greasy particles (e.g. kitchen exhaust air).