Obviously this testing is more stringent and requires a special louver design to perform well in this environment. As described earlier, the air intake velocity is the only variable. Two tests are common - 3" per hour rainfall combined with 29 mph wind speeds, and 8" per hour rainfall combined with 50 mph wind speeds. Testing procedures have fixed values for water volume and the wind speeds applied. Inefficient louvers will have values below 85%, meaning they allow over 15% of the water applied to pass through the louver. A very efficient louver will have a value from 99-100%. Basically, "how good is the louver at stopping the water?" The efficiency is rated as a percentage, determined from the amount of water that passes through the louver divided by the total water applied during the test. Instead of a "first point of water penetration" value, efficiency of the louver is measured instead. The wind is applied at a fixed rate, while the air intake velocity is increased from 0 feet per minute to a predetermined value. Testing is done similar to traditional louvers, but with wind simultaneously applied to the face of the louver. The result of this test is the first point of water penetration - ranging from 300 fpm (a very poor resistor to water entrainment) to 1250 fpm (a very good resistor to water entrainment). The velocity of airflow through the louver free area is increased until the louver allows water to enter. The typical method of testing for water penetration is to intake air through the louver while applying a measured water content into the airstream. It is a threshold measurement of air intake velocity at which the louver will begin leaking (in feet per minute or fpm). Louver Water Performanceįirst Point of Water Penetration is the point at which a louver allows the passage of water through the louver. A properly designed louver will maximize free area while allowing a minimal amount of water to enter.įor more information about free area, please visit the linked page Louver Free Area. A fully obstructed opening would allow no water in, while a totally unobstructed opening would allow water to enter unimpeded. Obviously some obstruction is required in order to keep undesirable water out. A high percentage free area is beneficial because more air can enter into a smaller wall opening, reducing the cost of the wall opening and louver. Common louver free areas range from 35% to 60% of the wall opening (65% to 40% obstructed). This gives a comparison of a louvered opening to an unobstructed opening. Once these concepts are understood, they can be used to properly apply a louver.įree area is derived by taking the total open area of a louver (after subtracting all obstructions - blades and frame) and dividing by the overall wall opening. Water Penetration, and Resistance to Airflow (Pressure Loss). The basic considerations for selecting louvers are A number of fixed or operable blades mounted in a frame can provide this functionality. Depending on the room, we might need to perform multiple air changes per hour to achieve our desired air quality in that room.A louver is a ventilation product that allows air to pass through it while keeping out unwanted elements such as water, dirt, and debris. In order to remove these air pollutants, we have to change the air in the room by introducing new volumes of air. Having adequate ventilation and airflow in a room is essential for breathing and for some appliances and equipment to work properly.Īside from that, with correct ventilation, we can control the humidity and temperature in a room and quickly remove any odors, fumes, and even particles that might linger, like in the kitchen or living room. Each room has a specific purpose, and we stay in each room for different amounts of time during the day.ĭepending on the activities we do in a room, the ventilation required to maintain a fresh air flow will change. In most workplaces, we usually have a lobby or receiving area, hallways, function rooms, offices, restrooms, and so much more. We commonly find a living room, bedroom, dining area, kitchen, and bathroom in a basic house. In any building, there will be a variety of rooms with various functions and purposes.
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