6. Partially open the vent valve (sealing plug with vent valve) on the negative side of the
pressure transmitter until condensate escapes without bubbles.
7. Close the differential pressure valve ③.
8. Partially open the differential pressure valve ④ until condensate escapes without bubbles.
9. Close the vent valve with blanking plug on the negative side ①.
10.Close the differential pressure valve.
11.Open the differential pressure valve ③ by half a revolution.
12.For the start of scale value 0 bar, check the zero point (4 mA).
If the differential pressure lines ⑤ have equally high condensate columns with the same
temperature, the measurement result is error-free. Otherwise, repeat the zero-point
adjustment.
13.Close the stabilizing valve ②.
14.Fully open the differential pressure valves ③ and ④.
Cleaning process cable
1. To clean the line, briefly open the drain valves ⑦.
2. Close the drain valve ⑦ before vapor escapes.
Commissioning
6.5 Differential pressure and flow rate
SITRANS P320/P420 with 4 to 20 mA/HART
Compact Operating Instructions, 09/2018, A5E38874562-AB 53