Build laminar flow hood7/9/2023 ![]() This chart shows the curves for 4 different particular models of axial duct blowers. NOTE: Each model of a blower has his own characteristic curve. Here is such a set of curves for 4 blowers(numbered 1-4). So if you use the above filter with 1"(250Pa) static pressure and a furnace prefilter with a static pressure of 0.2"(50Pa) your blower must deliver 200 cfm(340m 3/h) of air at a static pressure of 1.2"(300Pa).Įach blower has a data sheet (consult the manufacturer if this is not the case with your blower) where the correlation between the volumetric flow and the static pressure is represented by a graph or table. So 200 ft 3/min(= cfm = "cubic feet per minute") is the amount of air your blower must deliver at the sum of the STATIC PRESSURE of the HEPA filter + prefilter. Find out the area of your filter by multiplying the width and the hight in feet (for instance the smallest reasonably usable filter would be 2ft x 1ft) Determining the correct blower for a filter consists of several steps:ġ. ![]() 347 ff) the air speed of the air flowing from the filter surface should be (at least) 100 feet per minute(fpm).(around 30 meter per minute or 0.5 meter per second). It can be assumed that the static pressure for this prefilter at the working point is around 0.2"(50 Pa)Īccording to Stamets ( Paul Stamets and J.S.Chilton: The Mushroom Cultivator p. Before the air enters the blower it is usually pre-filtered by a furnace filter around 1"(2.5cm) thick placed in front of the blower to protect it and the HEPA filter from big particles like dust and hairs. Each filter has a data sheet (consult the manufacturer if this is not the case with your filter) where the static pressure at the working point is entered. The static pressure is expressed in inch of water column in the English units, a typical value would be 1", the SI unit for pressure is Pa(Pascal).ġ" water column is around 250 Pa. The working point is where the amount of the air flowing through the filter is sufficient to meet the requirement of the laminar flow. Dependant on how firm you press it against your mouth, you will have some difficulties blowing air out and you will feel some resistance, this is the static pressure.Įvery filter has a different static pressure at the working point. This is a very important step, so make sure to study the directions thoroughly.Įvery filter has a "resistance" when air blows through it at a certain speed, this resistance is called the "static pressure". Once you decided on the size of the HEPA filter, you have to match a suitable blower to this particular filter. While we can custom build any size cabinets to meet your needs, the available sizes we can offer are 3 foot, 4 foot, 5 foot and 6 foot.Australia | Austria | Canada | France | Germany | India | Israel | Italy | Netherlands | Norway | Russia | Slovenia | Sweden | Switzerland | United Kingdom | USA | Turkey | USA | Yugoslavia The units can be customized for your utmost functionality and ergonomy. Ceiling mounted airflow hoods, are normally used for air re-circulation purposes within a given space. Horizontal airflow hoods will circulate the filtered air from the back of the chamber to the front, while the vertical airflow hoods will circulate the filtered air from the top of the chamber towards the bottom. No ducting is required to the outside of the building. The Laminar Airflow Hoods mainly provide product protection, and depending on your application, you can select the type of air circulation either vertical or horizontal as required. Laminar Airflow Hoods provide a HEPA filtered, and if customized they can also provide an ULPA filtered clean air environment when working on applications that require protection from outside harmful contaminants. ![]()
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