Patent Number: 
Section: claims

1. A testing device, comprising:a test tank that stores cooling water therein;a foreign matter inputter that inputs foreign matter to the test tank;a recirculation sump screen set in the test tank and that filters the foreign matter; anda processor,wherein the processor executes a program for evaluating an amount of foreign matter passed through the recirculation sump screen, the program causing the processor to perform:acquiring sets of test data on amounts of foreign matter passed through a recirculation sump screen when different amounts of the foreign matter are input;forming a passed foreign matter amount approximate line that approximates the amounts of passed foreign matter with respect to the amounts of input foreign matter on the basis of the sets of test data on the amounts of passed foreign matter;forming a passed foreign matter amount line tangent to the passed foreign matter amount approximate line; andcalculating a total amount of passed foreign matter with respect to the amounts of input foreign matter on the basis of the passed foreign matter amount line to evaluate the recirculation sump screen. 2. The testing device according to claim 1, wherein the passed foreign matter amount approximate line is a quadratic curve and the passed foreign matter amount line is a primary expression straight line expressed by a function of an input foreign matter amount. 3. The testing device according to claim 2, further comprising forming a passed foreign matter amount approximate straight line on the basis of the passed foreign matter amount approximate line and forming the passed foreign matter amount line on the basis of the passed foreign matter amount approximate straight line. 4. The testing device according to claim 1, wherein a passed foreign matter amount line is set in a length defined by the passed foreign matter amount line tangent to the passed foreign matter amount approximate line and a passed foreign matter amount line shifted to a pre-set side where the passed foreign matter amount increases. 5. The testing device according to claim 4, wherein the length is a length moved to a side where the amount of passed foreign matter is smaller than a maximum value of the sets of test data on the amounts of passed foreign matter. 6. The testing device according to claim 2, wherein a passed foreign matter amount line is set in a length defined by the passed foreign matter amount line tangent to the passed foreign matter amount approximate line and a passed foreign matter amount line shifted to a pre-set side where the passed foreign matter amount increases. 7. The testing device according to claim 3, wherein a passed foreign matter amount line is set in a length defined by the passed foreign matter amount line tangent to the passed foreign matter amount approximate line and a passed foreign matter amount line shifted to a pre-set side where the passed foreign matter amount increases.