Emerson manual Can I calibrate a badly plugged diffuser?, SPS 4000 Troubleshooting

Oxymitter 4000

Instruction Manual

IB-106-340 Rev. 3.0 December 2003

3.Always note the time it takes for the cell to recover to the normal process value after the cal gas is removed. As the diffuser plugs, this recovery time will get longer and longer. Use the Calibration Record form provided in this manual.

Can I calibrate a badly plugged diffuser?

1.It may not be possible to immediately replace a plugged diffuser while the process is on line.

2.One can calibrate the probe without pressurizing the cell by adjusting the calibration gas flow rate downward before calibration. For instance, say the process is at 3%, and the first calibration gas is 8%. Adjust the flow of cal gas downward until the reading begins to migrate from 8% to lower values, indicating that process gases are now mixing in with the calibration gases.

3.Adjust the flow rate back up until this mixing is just eliminated. Calibrate at this flow rate. Replace the diffuser at the first opportunity.

Install all protective equipment covers and safety ground leads after trouble- shooting. Failure to replace covers and ground leads could result in seri- ous injury or death.

8-7 SPS 4000 TROUBLESHOOTING

Use the CAL FAIL and IN CAL relay outputs to identify possible SPS 4000 faults.

a.If a calibration was not successfully com- pleted, the SPS 4000 sends a CAL FAIL contact indication to the control room. To determine if the SPS 4000 caused the failed calibration, go to the Oxymitter 4000 site to view the keypad. Or, access the HART/AMS menus. For more information on HART/AMS, refer to Section 7, HART/AMS.

1.If no alarms are indicated on the key- pad or in the HART/AMS STATUS sub-menu, the calibration did not fail because of an Oxymitter 4000 fault. Therefore, a calibration gas flow prob- lem occurred. Refer to Table 8-3or Figure 8-19to troubleshoot the SPS 4000.

2.If the LAST CAL FAILED alarm is indi- cated on the keypad or in the HART/ AMS STATUS sub-menu, the failure is due to either a bad Oxymitter 4000 cell or a calibration gas flow problem.

(a)Verify your calibration setup per paragraph 9-2in Section 9, MAIN- TENANCE AND SERVICE, Also, verify your calibration gas setup.

(b)Perform another calibration and monitor the process. If the calibra- tion fails before both calibration gases finish sequencing, a gas flow problem exists. Refer to Table 8-3or Figure 8-19to troubleshoot the SPS 4000.

If the calibration setup is correct and the Oxymitter 4000 indicates an invalid slope fault (fault 13) be- fore the gases are purged and a last calibration failed fault (fault 15) after the gases are purged, replace the Oxymitter 4000 cell per para- graph 9-4iin Section 9, MAINTE-

NANCE AND SERVICE.

b.If a semi-automatic or manual calibration is being performed but no 5 - 30 VDC relay output contact (IN CAL or CAL FAIL) is be- ing received by the control room, the inter- face board relays are malfunctioning. Replace the interface board per paragraph 9-5b.

NOTE

If the unit is performing frequent auto- calibrations, investigate at the Oxymit- ter 4000 site or using HART/AMS. This condition may indicate an aging cell in the Oxymitter 4000.

Rosemount Analytical Inc. A Division of Emerson Process Management Troubleshooting 8-21