此外，第一和第二止回模块是相同的，可以互换。

Also, the first and second check module are identical and can be interchanged.

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可安装止回阀或订制自带止回功能的阀。

Can be installed or custom built non-return valve function of the valve.

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安装在阀门内的止回模块其阀座应该面对阀门进口。

Check modules are installed in the valve body with the seats facing the valve inlet.

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