Emerson Rosemount 228, Справочное руководство, Страница: 21 / 44

2. Drain the retraction chamber using 1/8 in. flush ports.
3. Loosen the 3 in. hex union nut and remove the retraction stop collar and orange
clamp top. Remove the sensor and tube assembly.
4. Replace the 3 in. hex nut O-ring. Place the sensor and tube assembly back in the
retraction assembly. Replace the retraction stop collar about 1/2 in. in front of the
clamp. Tighten the clamp screws, retraction stop collar, and 3 in. hex union nut.
Verify that the 1/8 in. flush ports are closed.
NOTICE
With the ball valve fully closed and the retraciton chamber 1/8 in. flush ports open,
some residual process fluid maay leak from the 3 in. hex union female ACME threads.
This leakage is normal and to be expected.
5. Before opening the ball valve, make sure that the process pressure is less than 295
psig (3135 kPa [abs]). Open the valve, check for leaks, and insert the sensor into the
process.
2.2.3 Replacing Seals in Manual and Mechanical Retraction
Assemblies
1. Retract the sensor into the retraction chamber and fully close the ball valve.
2. Drain the retraction chamber contents using the 1/8 in. flush ports.
WARNING!
HIGH PRESSURE
Retraction chamber contents may be under pressure. Reduce pressure to 0 psig before
opening the retraction chamber.
Failure to reduce pressure may cause a loose part to disengage and cause injury to
personnel.
3. For mechanical retraction assemblies, mark the location of the nut housing cap and
retraction collar on the sensor tube. Remove both socket head cup screws from the
nut housing and loosent the retraction stop collar.
4. Remove the 3 in. hex union nut.
5. Withdraw the sensor from the retraction chamber.
6. Open the junction box and disconnect the sensor wires from the terminal block.
7. Remove the compression fitting just below the junction box and remove the
junction box from the sensor tube.
8. For manual retraction assemblies, pull down the nut guard and remove the collet
nut from the bushing housing.
9. Slide all hardware, including the bushing housing, off the sensor tube.
10. Remove the retaining ring from the bottom of the bushing housing.
11. Remove the Teflon guard.
Install
Rosemount 228 Sensor 15