Gauges and Transmitter Location

The designer has to fulfill requirements given by Process Department, while codes, regulatins and standard practice has to be followed.

Depends on many factors.

To name a few:

• System Type
• large oil refinery
• power plant
• small hydraulic power supply
• etc
• Type of fluid used
• Purpose of the design
• If an active control system is being utilized, then sensor placement will be dictated by the necessity of a cost effective design robust enough to meet the performance requirements of the design. This could be as simple as a temperature sensor at the output or as complex as pressure and temperature sensors spread throughout the system.
• If the system is basically passive with only human intervention to close the control loop, then perhaps only gauges are needed (as opposed to transducers).
• Design requirements due to
• Customer
• may require gauges or sensors directly
• customer requirement may result in the need of a sensor/gauge at particular locations
• State/industry regulations - generally for safety purposes.
• Maintenance
• Reliability
• too many gauges and sensors will require excessive calibration
• Potential source of leaks

This is no way a comprehensive list, just what springs to mind at this early hour.

To simplify such complicated decisions is difficult, but generally, the placement of a guage or transmitter is dependent on the information needed about the process.Some require an exact location, and others are not so critical, and is left to the installer to determine, based on local conditions.Normally, all guages,sensor, or tranmitters will have instructions that may include the number of upstream straight pipe diameters(certain flow meters), whether it is to be mounted below(steam) or above (gases) the pipe, or whether it will reqiure a pigtail to trap condensate, whether guages are to be plain or liquid filled(High vibration), whether the sensor will be installed in a well or directly in contact with the process medium, and other vairables.

On a new machine, locations can be specified more exactly than on a retrofit, due to existing conditions that cannot be predicted.Contractors usually have some lattitude in chosing location as long as it fulfills the intent of the design.

HTRN

You have to also look at the design of the transmitter.

Take for an example of a RTD with a probe, I always mount the probe on an elbow to the stream with the probe parallel to the incoming stream. Mounting it perpendicular to the stream puts stress on the probe itself causing premature failure.

Pressure transducers are different, You to not want direct contact between the diaphragm and the flow, due to surges within the flow (hammer), this could damage the diaphragm.

As far as location placement, you need to discuss this with the process engineer.

p911

and that is the real question..how is it process engineer will determined where should the instrument will be mounted..?

thanks for all the answers guys!