## 3 Results
In the lower part of the reference measuring circuit A, a first fluid tank 7 is located, which is connected to the first heater 1 and to the first Section 2 of the tandem hydraulic pump for sucking the working fluid into the first three-way valve 13. Between the first Section 2 of the tandem hydraulic pump and the first pressure sensor, a first sampling outlet 9 is located. A first pressure sensor 10, a flow sensor 11 and a temperature sensor 12 are arranged between the first heater 1 and the first three-way valve 13, the first three-way valve 13 being connected to the first original filter 14 and to the first tested filter 16. The first original filter 14 and the first tested filter 16 are connected at the outlet to the second three-way valve 15. A second sampling outlet 17 is located between the second three-way valve 15 and the second pressure sensor 19. Behind the second pressure sensor 19, the flow sensor 18 and the temperature sensor 21, there is a first throttle valve 20. The reference measuring circuit A is connected in both directions via the first Section 2 of the tandem hydraulic pump to the test measuring circuit B via the second Section 2 of the tandem hydraulic pump. The measuring circuit used new oil. The connection of measuring circuit B is similar as measuring circuit A (Figure 3). By circuit B it is possible to simultaneously measure more different engine filter at once (max. 4 pieces) with two different types of engines oil. With laboratory device is also possible to simulate and compare different operational condition, e.g., a higher level of oil contamination or different level of filter clogging (Figure 3). All sensors, first temperature sensor 12, second temperature sensor 21, third temperature sensor 28, fourth temperature sensor 37, first flow sensor 11, second flow sensor 18, third flow sensor 27, fourth flow sensor 34, first pressure sensor 10, second sensor 19 of the pressure, the third pressure sensor 26, the fourth pressure sensor 35, and the frequency converter 5 are connected in two directions to computer 38 in the recording and evaluation circuit C for the transmission and processing of the recorded data. Subsequently, the obtained data are processed by computer 38 in table and graphic format. If the measurement methodology is followed, the repeatability of the measurement in laboratory conditions is guaranteed, and thus the possibility of monitoring the influence of different degrees of contamination of oil fillings on the flow properties of filter materials and their ability to separate impurities is ensured. The device for simultaneous testing of flow properties of filter materials allows measuring the flow properties of original and tested filter materials in each circuit while maintaining the same input conditions, and monitoring the filtration efficiency using mineral, synthetic oil fillings, but also oil fillings with different degrees of contamination and pollution. During the measurements, it is possible to simulate the conditions that are achieved in the lubrication circuit of the internal combustion engine by means of the first heaters (1, 22) and throttle valves (20, 36). The device allows monitoring of operating conditions recorded by temperature sensors (12, 21, 28 and 37), flow sensors (11, 18, 27 and 34) and pressure sensors (10, 19, 26 and 35) depending on the selected rotation speed, which are set by means of frequency converter 5 and a load exerted by the first throttle valve 20 and the second throttle valve 36. It is also possible to monitor the effect of contaminated oil fillings on filter materials and their ability to separate impurities.