Mechanical VRL1 Volume Flow Limiters that can be operated without an additional power supply are suitable for constant air flow applications. Maintenance-free VRL1 Volume Flow Limiters can be installed in the air-conditioning systems at any angles. The regulation and stabilization of air flows at set values are enabled by them independent from pressure. VRL1 Volume Flow Limiters consist of the enclosed setting and control mechanism which is protected against the contamination resulted from air flow. A complete enclosure is provided because VRL1 Volume Flow Limiters are fixed inside the ventilation ducts by the lip seals on the both sides. They consist of the casing and damper blade made up of the antistatic and microbial resistant special plastic material. The smooth surfaces of VRL1 Volume Flow Limiters prevent the contamination and so they carry out the latest hygienic requirements. VRL1 Volume Flow Limiters with the circular casing can be supplied in the different sizes from DN 80 to DN 250. They can be used for the air flow rates from 13m³/h to 1060 m³/h and the pressure values from 30 Pa to 300 Pa. The operating temperature for them is between 10°C and 50°C. VRL1 Volume Flow Limiters have an Environmental Product Declaration and Hygiene Certificate.