Wireless systems 1

[Jeremy6]

Just wondering what the specification requirements for a wireless system that meets the operational needs of an off-shore petroleum processing platform.

Looking for details covering the functional, operational, performance, and maintenance requirements.

Such things as:
- Data reporting frequency
- Obstruction density
- How to get around obstructions that block, reflect and otherwise impede transmission of wireless signals
- Antenna location
- Report information size (bytes)
- Distance between sensors

Any information about this or where I could obtain some would be greatly appreciated.

Thanks,
Jeremy

 

[Comcokid]

There is not enough information in your question to know what you are after. A wireless sensor system? To monitor what? Temperature? Fluid Level? Occupant tracking/sensing? (i.e. open loop reporting) or processes control loop feedback (closed loop operation)?

I know the following fluid level sensors, pressure, and 4-20 mA wireless battery operated sensors are intrinsically safe, and are being used in some applications to measure the levels in portable tanks used on off-shore platforms. See

http://www.centeron.net

 

[Jeremy6]

I am working with a company that is developing "Petroleum Applications for Wireless Systems."

I am looking for the specifics on wireless systems in general. Such things as Obstruction density, antenna placement etc.. all things that will give us a general idea of what hurdles we have to over come.

If someone has specifics on a wireless system that is in place about any of these areas or related areas I could really use the information or direction as to where to get it.

I'm finding if very difficult to find resources that give me these details.

Thanks,
Jeremy

 

[VEBill]

(Lack of...) Reliability of the "wireless" link is going to be a tremendous issue for anything related to safety, pollution, huge stacks of money... Sounds like a non-starter to me.

The technologies that can help are spread spectrum, Forward Error Correction, diversity antennas, two-way hand-shaking like packet radio ('acks'), etc.

"Wireless" (also known as "Radio") has been around for a while and the failure modes of various bands and techniques are all very well known.

 

[VisiGoth]

Off shore rig data will not be done by a do it yourself operation. They will hire a consultant to help evaluate the options, then hire a company to be esponsible for all those aspects you mention, and more.

 

[VEBill]

"They will hire a consultant to help evaluate the options..."

Perhaps that is what we're witnessing.

 

[VisiGoth]

VE1BLL,

That is a scary thought, but hopefully not true. There must be some important RF interference issues since all RF is so close.

 

[Comcokid]

The Centeron product I mentioned is a Direct-Sequence-Spread-Spectrum system in the 915 MHz band and uses a receiver with diversity antennas. It is used to monitor the level in portable chemical tanks so the distributor knows when to make a trip to refill. The normal line-of-site range for this system is greater than one mile, so there is plenty of path margin in the system to cover a oil-well platform - especially since the receiver is usually in a metal-sided room with only a few small windows for RF openings.

For simple reporting and monitoring applications, wireless is an excellent choice. Especially for tanks that may be moved frequently and sometimes replaced/swapped during a delivery. Additionally, in this application intrinsic safety is a must.

Wireless is ideal where things the items being monitored move, are widely dispursed, or it is just not pratical to put a wired-link between the points. This usually means the items are not part of a active process loop.