The Collapse Measurement app measures the cyclical vacuum variation in the milking claw. If the vacuum variation is too high, there is a risk of bacteria being transferred between teats. The vacuum variation is caused by the change in capacity of the space volume under the teat, which is caused by opening and closing the teat cup. The milking speed (creates resistance in the outlet), the tension of the teat rubber, the size of the space volume under the teat, the diameter of the short milking tube and the type of vacuum system used (simulate or alternate) are aspects that influence the cyclical vacuum variation. The second purpose of collapse measurement is to measure the milk and rest phases. The milk phase/rest phase ratio is measured by an intersecting line that is a few kPa (Inch Hg) lower than the milk vacuum. This kPa (Inch Hg) level is roughly equal to the vacuum difference necessary to open and close the liners.