1、 Structural judgment method Observing the structure of a filter is one of the common methods to determine its inlet and outlet. Most filters have a clear inlet and outlet, and their structural characteristics can be clearly distinguished. Generally speaking, the inlet of a filter is larger in appearance and has a different shape than the outlet, and some may even have an import label. Meanwhile, imports are usually straight through, while exports are usually curved or connected to other pipelines. By observing their structure, one can preliminarily determine their imports and exports.

2、 Identification judgment method Some filters are labeled at the inlet and outlet in their design, making it easier to determine. The entrance is usually marked with "Inlet" or "In", while the exit is marked with "Outlet" or "Out". In addition, some manufacturers also mark arrows on the filter to indicate its flow direction. By checking these labels, you can also more accurately determine the inlet and outlet of the filter.