Redundant Sensoring for CSO monitoring: is proximity in location important or not and why?

[MunicipallyMinded]

I'm a recent college grad entering the field as a civil engineer. In my past experience, redundant level sensors have been placed in the same CSO structure. I'm reviewing a project where the design engineer has placed the redundant level sensor in a structure downstream that also needs level monitoring to maximize sensor coverage. With my limited experience and general knowledge of hydraulics, I think this should suffice but I wonder, for monitoring purposes, proximity in location is best when identifying things like sensor drift. I asked around and no one seems to be able to give me a solid technical reason as to which arrangement is preferable or if they are interchangeble. The business need is for the most accurate measurements in order to collect overflow volumes and/or use level measurements for gate operation.

Thanks for your help!

 

[cvg]

well, if it's not in the same structure, than you really don't have a redundant system. hard to validate the data from the main sensor when the redundant sensor is located somewhere else.

 

[MunicipallyMinded]

That's what I thought. I examined the plans more closely and noticed that the HGL isn't even the same in two places where the sensors were called out with their SCADA tags that alluded to redundancy. The more I think about it, I don't see a total need for redundancy at one particular monitoring point. Monitoring is simply there to note how storage is being utilized. I think it is a mistake in tag-naming conventions. There is one more instance of a faux redundancy in an area that I feel actually requires redundancy so I'm going to just sit down with the design engineer later this week and pick his brain about why he chose this monitoring strategy. Thanks for the help. My boss is on vacation and I dont want to bug her with my newbie questions.

 

[cvg]

redundant sensors are commonly used, it is more expensive but will provide more reliability. It may be the designers choice, but could be a requirement of a regulatory agency.

 

[MunicipallyMinded]

Some redundancy is part of a regulatory requirement that I am not completely familiar with. I suppose I could read it for more clarification to understand the items that bring us into compliance. Aside from that, the business need for redundancy is to eliminate unecessary deployment of crews due to equipment failure alarms during normal flow conditions.