Patent CA-1301480-C (CA)
Title: Device to test the permeability to air of two-dimensional articles, in particular, of felts and screens used in machines and installations for manufacturing paper
Inventor: SCHLIPF ENGELBERT
IPC: G01N15/08
Filed: 1987-04-06
Granted: 1992-05-26
Abstract: ABSTRACT OF THE DISCLOSURE           There is provided a new and useful device for testing the air permeability of an article, and particularly felts and screens associated with the manufacture of paper products, the device being of the type including a measuring channel through which air is propelled through utilization of a blower mechanism, and including measuring means for measuring the flow rate of air within the measuring channel, the air being propelled through a measuring area of the exposed surface of the article as a function of a controlled constant pressure difference created at the adjacent measuring area, the device further being of the type including a longitudinal positioned belt channel juxtaposed about the measuring channel in which the belt channel is additionally and operably directing propelled air from the blower mechanism, wherein the measuring channel and the belt channel each further include an orifice immediately adjacent to the exposed surface of the article, the improvement  in  the  air  permeability  testing  device  further comprising:   the blower mechanism,  the measuring channel,  the measuring means for determining the rate of air  flow in the measuring channel, the measuring area and the belt channel being integrated into a single operational testing device capable of being placed for air permeability testing to one of either of two sides of the article being tested; the measuring means comprising a  fan wheel  anemometer  having  a  fan wheel  element  operably positioned within the measuring channel for direct exposure to the air being propelled therein; the measuring channel containing the fan wheel anemometer wheel element being operably connected to the orifice of the measuring channel  immediately adjacent to the article through a channel section element, immediately adjacent the measuring channel orifice having a substantially cylindrical longitudinal construction, with the channel section further and operably being attached to a tapered longitudinal section emanating towards the measuring means in order to insure that the propelled air stream is unidirectional; the air permeability testing device further including in at least one position upstream from the fan wheel element of the fan wheel anemometer, flow rectifier means for precluding the creation of rotational flows of propelled air onto the surface of the fan wheel element;  the substantially cylindrical longitudinal section immediately adjacent the measuring channel area having one or more sensing means operably associated therein for measuring the extent of static pressure created at the area of measuring channel,  for the purpose of regulating the rotational speed of the blower mechanism so as to maintain a desired static pressure value; one or more of the belt channel and the measuring channel means being of such a geometric configuration so as to equalize the propelled air flow volume and velocity longitudinally conducted through the belt channel to the propelled air flow volume and velocity longitudinally directed through the measuring channel.