Boiler blowdown, which is simply the removal of water from a boiler, is a very important part of any water treatment program. Blowdown occurs when water is removed from a steam boiler while the boiler is operating with the use of valves: motorized valves or solenoid valves.
What Are Motorized Ball Valves Used For?
Steam boilers evaporate water to form… you guessed it! Steam. As water evaporates, impurities become concentrated. This is commonly referred to as “total dissolved solids” or TDS, and it’s highest where moisture is produced: near the heat exchanger surfaces. If the level of TDS becomes excessive, scale will form on those surfaces. These scale deposits act as an insulator and reduce the heat transfer rate, resulting in inefficiency and reduced steam production. In severe cases, the heat transfer can be reduced to the point where the heat exchanger is at risk of damage due to excessive temperature. TDS in boiler water can be controlled by draining boiler water. Fresh make-up feed water dilutes the boiler water, reducing the level of total dissolved solids.
The level of TDS in water is directly proportional to the conductivity of the water, measured in micro siemens (µS). A boiler water treatment controller measures the conductivity and opens/closes a blowdown valve accordingly to maintain a conductivity setpoint, determined by a water treater for the particular circumstances and application. There are two types of boiler blowdown valves.
Motorized Valve vs. Solenoid Valve
There are two types of boiler blowdown valves, a solenoid valve and a motorized valve. A solenoid valve uses a wire coil around a metallic stem/plunger. When electricity is applied to the coil, it becomes magnetic and pulls up the stem. Some solenoid valves use upstream pressure to assist that movement. When de-energized, the valve stem returns to a closed position. Solenoid valves open and close very quickly but have lower flow limitations than a ball valve.
Motorized ball valves (MBV) use a motor to rotate a ball with a hole through the middle. Flow is allowed when the hole is in line with the piping. Our MBV is powered open and powered closed. They are much more durable than solenoid valves.
Boiler Blowdown Control at Lakewood
At Lakewood, we recommend using our Valvcon boiler blowdown valves. These motorized ball valves are ideal for the control of the boiler’s surface blowdown, and when wired to a Lakewood 150, Lakewood 1575e or a NexSys, will complete the control loop for conductivity. We’ve sold hundreds throughout the years with a failure rate near zero. If you have any questions, please get in touch with us or request a quote for the Valvcon motorized ball valves.
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