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The article deals with the adjustment of the flow rate of milk and water by a plate heat exchanger, which is used for precooling milk. First, measurements of the parameters of the device in the stable were carried out. Subsequently, the plate heat exchanger was measured in the laboratory. Water at 35 °C was used instead of milk. Different flow ratios of cooling water and cooled water (instead of milk) were set. From the measured values, changes in the temperature of cooled water were calculated depending on its flow rate at a constant ratio of cooling water and cooled water. It was found that in the measured range, there are flow values at which temperature change is maximal. This dependence applies to all selected cooling water and cooled water flow ratios: (0.8, 0.9, 1.0, 1.1, 1.2.). The results show that with the same amount of cooling water, it is possible to achieve greater cooling of milk by 0.7 to 1.6 °C, or to achieve a reduction in water consumption. The device on the farm was modified to allow the flow of milk and cooling water to be changed. The optimal values found were set, and verification measurements were performed. The saving of 4.8% of cooling water was confirmed.

Vacuum fluctuation was measured using three different vacuum control methods. Firstly, the use was made of a control valve delivered by the manufacturer; then, an additionally installed frequency converter was used. Lastly, a frequency converter fitted with the stabilisation device prototype was used. First, control sensitivity according to ISO was measured in all the three alternatives. Then, vacuum fluctuation during milking was measured. To conduct the measurements under objectively identified conditions, another measurement was conducted with air feed during milking being replaced with a precisely defined variable flow rate. The conducted measurement confirmed the fact that when the frequency converter is used, vacuum fluctuation in stabilised condition is at the same level as when the control valve is used. If there are sudden changes in flow rate and the frequency converter is used, vacuum fluctuation increases. The proposed stabilisation device prototype can reduce the fluctuation in small milking plant but it is not suitable in large milking parlours.

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Vacuum fluctuation was measured using three different vacuum control methods. Firstly, the use was made of a control valve delivered by the manufacturer; then, an additionally installed frequency converter was used. Lastly, a frequency converter fitted with the stabilisation device prototype was used. First, the control sensitivity according to ISO was measured in all three alternatives. Then the vacuum fluctuation during milking was measured. To conduct the measurements under objectively identified conditions, another measurement was conducted with the air feed during milking being replaced with a precisely defined variable flow rate. The conducted measurement confirmed the fact that when the frequency converter is used, the vacuum fluctuation in the stabilised condition is at the same level as when the control valve is used. If there are sudden changes in the flow rate and the frequency converter is used, the vacuum fluctuation increases. The proposed stabilisation device prototype can reduce the fluctuation. [ABSTRACT FROM AUTHOR]