The Gurley 4150 is a high pressure densometer intended to measure the air permeability of materials with low air permeability.
The densometer measures the time taken for a given volume of air at constant pressure to pass through a defined area of the test specimen.
The sample is clamped between plates containing a circular orifice and therefore, the surface of the specimen must be smooth to avoid leakage of air across the surface.
The air pressure is supplied by a weighted inner cylinder floating freely within an outer cylinder which is partially filled with oil to act as a seal. The time is measured with a digital timer.
Typical materials include coated papers, plastics and membranes.
Air volume | 2.5 to 30cc |
Air pressure | 12.33 inches WC (3 kPa approx) |
Sample area | 1.00 sq inch (6.4 sq cm approx.) 0.25 sq inch (1.6 sq cm approx.) 0.10 sq inch (0.64 sq cm approx.) |
(ASTM D726-94(2003)) | Standard Test Method for Resistance of Nonporous Paper to Passage of Air |
TAPPI T 536 om-18 | Resistance of Paper to Passage of Air (High Pressure Gurley Method) |