Level, pressure and temperature instruments control the operation of the tower and must be placed in a position that enhances operation and maintenance without obstructing operator access.
Instrument requirements for towers are uaually highlighted on an instrument vessel sketch furnished by the instrument engineer.
Following figure shows a typical instrument vessel sketch. Level controllers, switches and gauges are either located individually or grouped on a common bridle or standpipe.
The controller must be operable from grade or platform; gauges and switches may be operable from ladder if no platform is available.
Following figure shows arrangement for level instruments.
Like level gauges, temperature and pressure instruments can be operable from a ladder if a platform is not available at the required elevation.
They can be read locally or in the main control room. Locally mounted indicators are available in variety of styles, with straight or
swivel heads that can be positioned for clear dial visibility.
Following figure shows typical temperature and pressure connections. The instrument arrangment shown below has been designed using the following information and guidelines in this chapter.
- Nozzle elevations.
- Instrument vessel sketch.
- Platform arrangement.
- Piping Arrangement
- Level instrument locations.