Paul, to answer your question,

1). For the drum levels we have two methods of indication..obviously the more the better. We have a level site glass as well as DP transmitters (for feedwater control) and local gauges. Transmitters such as those made by Emerson Rosemount are typical and what is most popular.


2). Would recommend setting up a Preventative maintenance schedule to calibrate the transmitters and gauges. Since this is a critical instrument, the more aggressive the better. We have our calibration intervals set up semi-annually for the drum level indications.

3). Glass? it typically varies site to site.. if your water quality is great, you wont need to replace or clean your site glass as often. poor water quality will start fogging the level indicator.
I hope this helps. thanks