| 摘要 |
PURPOSE: A low pressure gauge for an air duct expansion apparatus is provided to measure an internal balloon pressure with naked eyes or by a touch pressure. CONSTITUTION: The gauge comprises: a gauge body divided into an upper body and a lower body(44); a flexible tube(60) accommodated in the gauge body; a probe rod(70) constantly contacted to a side face of the flexible tube(60) and inched by a swelling pressure of the flexible tube(60); an equalizing spring(80) applying an elastic force to the probe rod(70) toward the flexible tube(60) to stop the probe tube(70) at the point where the elastic force and the swelling pressure of the flexible tube(60) form an equilibrium; an enlarging instrument(90) enlarging the inching of the probe tube(70); and a pointer needle(95) connected to the enlarging instrument(90) to indicate the swelling pressure of the flexible tube(60).
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