The bypass flow meter is installed in the water circuit of the HM 500 trainer. The flow rate is determined via an orifice plate flow meter in the main flow and a rotameter in the bypass flow.
The orifice plate flow meter constricts the cross-section in the pipe. The decrease in cross-section causes an increase in speed, which results in a drop in pressure. The bypass flow is created by the pressure difference. A rotameter is located in the bypass flow. The flow rate is read off the position of the float on a scale.
To display correct values, the rotameter must always be vertical. The rotameter in the bypass flow can be rotated relative to the orifice plate flow meter in the main flow so that it is always vertical. This means the bypass flow meter can be installed regardless of location.
In addition, the pressure drop across the bypass flow meter can be measured using pressure measuring points. This only makes sense if installed horizontally.