TABLE OF CONTENTS We mentioned several times in Chap. 9 that the noise analysis technique provides the dynamic response of not only a pressure transmitter but also its sensing line. That is, when the response time of pressure transmitters are tested using the noise analysis technique, the results include any delays caused by the sensing line's length; and the effect of any blockages or voids in the sensing lines are automatically accounted for in the results. [20] These points are further verified by the examples presented in this chapter.
Pressure sensing lines can become blocked for any number of reasons, including crud buildup, boron solidification, and isolation and equalizing valves that have been improperly lined up or incorrectly seated. These effects are accounted for when the noise analysis technique is used to measure response time of pressure transmitters. This is demonstrated by the results of laboratory measurements presented in Table 10.1 involving ramp and noise tests performed under the same conditions. The test setup and a photograph of the facilities used for these tests are shown in Figs. 10.1 and 10.2, respectively. The tests were performed according to the following procedure:
The response times of two fast-response reference transmitters were measured against one another. As expected, both the ramp and noise tests indicated a response time of essentially zero for the reference transmitter.
One of the two reference transmitters was moved away from the other using 35 meters of sensing lines. Its response time was then measured against the...
