The method of direction distinguishing not only is that used in heat transfer data processing of heat exchanger, but it is also used to find the solution of norm equation for pressure drop test.

方向鉴别法不仅可以用于换热器传热试验数据处理，也可用于压力降试验准则方程的求解。

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If pressure bleeds off there is clearly a problem with the pressure integrity of the shoe, However, industry practice dictates that a positive test, that is no pressure drop, is not diagnostic, simply because the reservoir pressure is sufficient to retain the pressure being applied.

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