The backflow preventer offers added protection preventing the system from emptying if supply pressure should fail.
Boiler feed water valve fail position.
Feedwater control valves play a critical role in boiler operation.
It is important to remember that valves are generally pneumatic meaning that their function is based off of air pressure.
The feedwater valves are normally sized to accommodate an operating condition that occurs when the safety valves open during a unit trip.
Boiler feedwater is treated to protect it from two basic problems.
Taco boiler feed valves have set the standard for dependable service.
It is critical not to allow the hrsg to dry out which can cause severe thermal damage to the boiler tubes and the drums.
Some typical applications are 0 135 ohm slide wires from a mcdonnell and miller 7b switch or a 4 20ma signal from a.
Loss of water to the deaerator or makeup water system.
Drum level controller failure.
Pressure drop so flow control is established by the valve position.
To protect against this the feedwater valves are sized for minimal pressure.
The valve s fail position is a safety precaution that protects your process in emergency situations.
N failure mode fail safe is the preferred failure mode which.
Loss of plant air pressure to the control valve actuator.
There are a few different fail scenarios.
Coupling dependable service with added protection into one quality product is taco s combination boiler feed backflow preventer valve.
Each having its own consequences and safety effects.
Drum level controller inadvertently left in manual position.
The buildup of solid deposits on the interior or water side of the tubes and corrosion.
Off of many types of signals.
They come in all types from ball valves to knife gates to globe valves and operate.
Safety valve lifting and then reseating.
Be a boiler feedwater regulator valve where a constant speed feed pump is used.
Large and sudden change in steam load and or.
Prevention of scaling or buildup the need for proper feedwater treatment is obvious if you will consider the comparison of a boiler and a pot of boiling water on the stove.
