theoretical relations. The spool works are given by a four ports valve

theoretical relations. The spool works within 2 % hysterisis, however. the resolution in the low flow rates range (below 10 L/min) is not good because of square curve characteristics. Figure 4 shows the transient characteristics of the flowmeter which are compared with pressure changes of the small fluid resistance orifice serially connected to the flowmeter. The flowmeter responds in 35 ms delay compared to the pressure changes of the flow step from 30 to 60 L/ain. The dynamic response for alternative flow change is shown in Fig. 5. The rectangulaly flow