Post by ivan on Sept 29, 2008 12:50:30 GMT
I thought radiators had to be earth bonded if plumbed with plastic pipe, due to modest conductivity of water.
Re pipe diameters, imagine dividing 4" pipe with a cross, so you subdivide the pipe into 4 qudrant shaped pipes, which might then peel off to 4 machines. (Ignore the thickness of the divider) You might imagine the speed of 4000 ft/min flow in the 4" main would result in 4000 ft/min in each branch. However, each branch of ~3" cross section has an effective diameter of just about 2". A 2" pipe has much more resistance to flow at 1000 ft/min than the 4" at 4000 ft/min. With the same fan flow is radically reduced overall. You get closest by making each 2" branch of minimal length (not very practical, and liable to high turbulence leading to more resistance to flow). In practice a standard bag extractor will be choked and the \airflow may reduce to the point that chips drop out of the flow. High revving vac cleaner type extractors can generate high flow in fairly short small pipes, but you need a lot of motors in parallel to shift much cu ft. Resistance to flow varies with both diameter and air speed; most reference libraries have heating and ventilation engineers bibles on the shelf with charts and tables to show this in detail, if you're interested.
Crown guard extraction with 2" hose probably only works when pipe is short, and when sawdust is directed into the duct.
Re pipe diameters, imagine dividing 4" pipe with a cross, so you subdivide the pipe into 4 qudrant shaped pipes, which might then peel off to 4 machines. (Ignore the thickness of the divider) You might imagine the speed of 4000 ft/min flow in the 4" main would result in 4000 ft/min in each branch. However, each branch of ~3" cross section has an effective diameter of just about 2". A 2" pipe has much more resistance to flow at 1000 ft/min than the 4" at 4000 ft/min. With the same fan flow is radically reduced overall. You get closest by making each 2" branch of minimal length (not very practical, and liable to high turbulence leading to more resistance to flow). In practice a standard bag extractor will be choked and the \airflow may reduce to the point that chips drop out of the flow. High revving vac cleaner type extractors can generate high flow in fairly short small pipes, but you need a lot of motors in parallel to shift much cu ft. Resistance to flow varies with both diameter and air speed; most reference libraries have heating and ventilation engineers bibles on the shelf with charts and tables to show this in detail, if you're interested.
Crown guard extraction with 2" hose probably only works when pipe is short, and when sawdust is directed into the duct.
