This is the tank that receives condensate return from the steam system and make up water as required in a power plant.

The boiler feedwater pump takes the water from this tank at pressures up to about 300 psi and boosts it to whatever pressure the boiler is operating at. The water in this tank is very pure, very hot and under pressure. The typical level control is a sight glass and perhaps a float switch for low level alarm.

Because of the operating conditions the sight glass is very thick and the level of the clean water is very difficult to see. The normal technique used in most plants is to shine a flashlight through the glass with your face next to the flashlight and glass, then move up and down along the length of the glass until you find the level. As one man from Houston Lighting & Power explained, "When we really want to know the level we send three guys out with flashlights. They each examine the sight-glass carefully, then vote on where the level is".

Power plants around the world are replacing old gauge glasses with magnetic gauges on feedwater heaters, not only for better visibility but reduced maintenance. Typical replacement costs for sight glasses on heaters in a single unit of the average power plant run about $10,000/year (high pressure side only). This means the mag gauges will pay for themselves in the first year.

Other applications for mag gauges in a power plant are:

• Deaerator (DA) Tanks
• Auxiliary Boilers
• Condensate Tanks
• Blowdown Tanks
• Hot Wells
• Drip Tanks
• Ammonia Tanks, Drums, Oil or Fuel Storage Tanks
• Water Treatment or Demineralizer Tanks
• Glycol Heat Exchangers
• Caustic Day Tanks
• Sulfuric Acid Tanks