Teledyne Deltaflow DF180, Руководство по эксплуатации и обслуживанию, Страница: 9 / 42

January, 2018
Page 9
1.1.2 Differential Pressure (DP) Transmitter
This device converts the pneumatic differential pressure signal measured by the probe to a 4-20mA
signal. It also provides a gauge style display to aid in troubleshooting the electrical signal. The gauge
needle can be zeroed and the 4-20mA signal can be calibrated at the display. Various ranges are
available; a TML Engineer selects the range based on process parameters of the application. See
Appendix A: Spare Parts for a complete list of all available ranges.
Fig. 1-3 Differential Pressure Transmitter with Display
1.1.3 Push Buttons
These buttons allow the user to start a blowback sequence, calibration check, interference check, or put
the Deltaflow into maintenance mode. Once pressed, the blowback sequence will start immediately.
Calibration and interference checks will start at the top of the next minute according to the controller
clock. Once pressed, the maintenance button will illuminate red and will put the Deltaflow into
maintenance mode until the button is pressed again. Maintenance mode causes the Deltaflow
controller to flag its’ data as invalid.
1.1.4 Valve Manifold Assembly
This assembly consists of 7 solenoid valves installed on a custom designed manifold. Static pressure,
impact pressure, and instrument air are directed through the manifold by the valves.
During normal sampling mode none of the valves are actuated; impact pressure and static pressure are
directed to the high and low sides of the differential pressure transducer, respectively. During a
blowback sequence or interference check, SV1 and SV2 send high pressure instrument air up the sample
line, while SV3 and SV4 isolate the differential pressure transmitter from the high pressure instrument
air.
The calibration check consists of a zero and span check. First, the DP transmitter high and low sides are
exposed to ambient pressure using SV3 and SV4. This provides a zero check. For the span check SV5,
SV6, and SV7 are activated. This allows low pressure instrument air to start pressurizing the DP
transmitter as well as the DP span set point switch. Once the DP span set point switch senses the correct
upscale pressure has been reached, it trips and shuts off SV6. This provides a stable upscale calibration
check. See the Plumbing & Instrumentation Diagram and the Timing Diagram in Appendix B for further
detail.