The patented Key-Valve® is the heart of the Key-System® and was developed specifically for use in waterless urinals. Without the use of water or other sealing liquids, it seals the drain opening to prevent the emission of odours from the drain.
Depending on the rate of urinal usage, the Key-Valve® must be replaced 2 to 3 times a year. Thus each valve can save up to 40,000 litres of water. The Key-Valve® works using Bernoulli's principle. Aided by cohesion of the moistened diaphragm, the valve remains permanently airtight. There is no risk of drying out because of the moist air in the drain line.
With the Key-Valve®, no siphon is required in the drain line. If a conventional siphon is in place, it does not affect the Key-Valve®. The Key-Valve® automatically balances vacuum phases in the drain line because the diaphragm allows flow into the drain. When the line is under pressure the diaphragm closes tight. The diaphragm is made of a special silicone rubber compound and possesses exceptional chemical and mechanical properties.