permeance การใช้

• Permeance is a measure of the quantity of flux for a number of current-turns in magnetic circuit.
• A magnetic circuit almost acts as though the flux is'conducted', therefore permeance is larger for large cross sections of a material and smaller for longer lengths.
• Magnetic permeance \ mathcal { P } is defined as the reciprocal of magnetic reluctance \ mathcal { R } ( in analogy with the reciprocity between electric conductance and resistance ):
• Involves materials with a very low permeance / porosity, such as hardwood floors, concrete, crawlspaces, plaster, etc . Drying generally requires very low specific humidity to accomplish drying.
• "' Air barrier materials "' Building materials that are designed and constructed to provide the principal plane of airtightness through an environmental separator, which has an air permeance rate no greater than 0.02 L / ( s " m?) at a pressure difference of 75 Pa when tested in accordance with ASTM E 2178.
• "' Air barrier accessories "' Products designated to maintain air tightness between air barrier materials, assemblies and components, to fasten them to the structure of the building, or both ( e . g ., sealants, tapes, backer rods, transition membranes, nails / washers, ties, clips, staples, strapping, primers ) and which has an air permeance rate no greater than 0.02 L / ( s " m?) at a pressure difference of 75 Pa when tested in accordance with ASTM E 2178.