| 摘要 |
<p>A pressure transducer having a pressure sensing surface spaced from an interior surface of the transducer housing by a relatively rigid back-up ring which contacts each of the pressure sensing surface, the interior surface of the housing and an interior side wall of the housing. A relatively less rigid O-ring is disposed between the pressure sensing surface and the interior surface of the housing and contacts the back-up ring, the back-up ring and the O-ring providing sealing of the pressure cavity. The O-ring communicates with the fluid entering the housing via an inlet in the housing. Because the output of the pressure sensing element is affected by the loading of the O-ring and back-up ring, and because this loading changes over time, mainly due to cold flow, compression set, etc.), several special procedures are provided during manufacture and before calibration of the transducers to minimize this problem to avoid calibration change (drift) over time, these being conditioning or burning in prior to calibration. This is accomplished by an extended high temperature soak through a series of pressure cycles or overpressure cycles or a combination thereof and permits the back-up ring and the O-ring to be relieved of stresses so that they will be stable over time.</p> |
