Endress+Hauser SS1000, Hardware Installation And Maintenance Manual

Page: 63 / 121

Sample Conditioning System
Hardware Installation and Maintenance Manual 4
–
9
1. Isolate the analyzer from the bypass following the procedure under
“To isolate the measurement cell for short-term shutdown”
on page 4-8.
2. Close the sample supply shut-off valve to the SCS.
3. Allow the sample bypass to flow until all residual gas has dissipated
from the lines as indicated by no flow on the sample bypass flow
meter.
4. Close the low pressure flare or atmospheric vent header shut-off
valve for the effluent from the sample bypass.
5. Turn off power to the analyzer.
To isolate the process sample tap for long‐term shutdown
If the SCS is to be out of service for an extended period, the SCS must be
isolated at the process sample tap.
Process samples may contain hazardous material in potentially
flammable and/or toxic concentrations. Personnel should have a
thorough knowledge and understanding of the physical properties
and safety precautions for the sample contents before operating
the SCS.
Although the pressure reducing regulator at the process sample
tap is designed for “bubble-tight” shut off, this condition may not
occur after the system has been in operation for an extended
period. Isolation of the SCS from the field pressure regulator will
discontinue sample flow and may cause the pressure at the outlet
of the field pressure regulator to slowly increase if “bubble-tight”
shut off of the pressure regulator does not occur. The slow
pressure increase will continue until the pressure setpoint of the
relief valve is reached and the excess pressure is vented by the
relief valve. Although this situation is not intended, it does not
cause a significant problem if the SCS is only isolated for a short
period. Only a small amount of process sample will be vented
when the relief valve opens because the pressure regulator will
continue to act as a flow restriction.
If the system will not be out of service for an extended period, it
is advised that power remain applied to the sample transport line
electric tracer, if applicable, and the sample system enclosure
heater.