• Not Answered



We faced a problem with one of our rotary SIS valve when a poisoner toke the valve toward faille plosion for 3 min then opened again by itself without a change in command signal. When maintenance team attend the valve they notice air is bleeding in pulses manner.  There was no alert triggered beside travel deviation alarm.

due to the criticality of the valve The poisoner then replaced with 6200sis.

The poisoner then put in a bench on a test valve and same scenario happen air start bleeding in pulses manner  no alert triggered, after I/P and Relay replaced the bleeding stopped.

our PM include a visual check for the valve and poisoner components. but the PM  intervals varies from valve to valve it could be as short as 1 month to 6 years.

Our question how to prevent that from reoccurrence to the rest of the valves?


Thank you in advance.

2 Replies

  • Please contact your local sales/ support team so they can help review the failure and make recommendations on how to avoid it in the future. If they need help there is an established escalation process that they will follow to reach the right people within our organization. Thanks for posting the question.
  • Hello Diaa,
    Field devices used in SIF (Safety Instrumented Function) - dormant in one static position are maintained differently vs devices used for BPCS (Basic Process Control System) - continuous moving. I am sure you follow IEC61511, operation and maintenance guide clause 16, section 16.2.2 and specific 16.2.8.
    Microprocessor based intelligent device like DVC6200 SIS have rich diagnostics, which allows to detect Safe (detected / undetected) and dangerous (detected and partly undetected during PST) failure modes and can provide indications in advance before hand.
    Also any field device, used for safety instrumented system, its safety manual provides preventive maintenance guidelines. Generally, conservative approach is taken in estimating the service interval for the digital valve controller in Safety Instrumented Systems. For SIS applications, preventive maintenance must be performed on the digital valve controller at intervals furnished in safety manual from the date of shipment. If the instrument is exposed to the upper or lower extremes of the environmental limits, the interval for preventative maintenance may need to be reduced.

    For present query, assuming that device was properly maintained per safety manual of DVC and installed per IEC61511 clause 14 with required guidelines like air filter regulator for air supply to Microprocessor based Digital Valve Controller etc., would require more details and possible local team involvement to suggest appropriate measures. If you can please furnish your contact details (email, phone or location), will have our local sales team to support further.
    Thanks & Regards