The blowdown valves are a very popular category of pipe valves, used in a wide variety of applications. They are used for operation in open position. The main function of blowdown valve is mainly to control a continuous flow of steam /fluid under high differential pressure. The outstanding feature of this type of valve is that it can maintain fluid tightness and it is easily operated without the help of any wedging action.
- Stainless steel
- Cast Iron
- Monel etc.
How does a blowdown valve operates?
The blow down valve dimension must be selected
according to the operating conditions. The factors to consider are:
- Working Pressure
- Working Temperature
- Exhausting Capacity
- End Connection
- End Usage
Features of blowdown valves:
- At start-up, the valve closes. This leads the air-oil separator
pressure to build up.
- At shut-down the valve opens to bleed the air-oil separator to
atmosphere. This is when a pressure is applied. The valve can also
be used as a by-pass valve to bleed air with the help of the
compressor at start-up.
Types of blow down valves:
- The design and materials of blow down valves must be such as to
minimize the effects of a fluid stream in conditions where water
contains sometimes abrasive particles.
- The outlet of such valves is always "Venturi tube"
shaped.The stem is rising non rotating.
- There is a local stroke indicator which shows the position of the
- The bonnet less design of the valve helps in easy dismantling,
inspection and maintenance.
Some types of blowdown valves are as follows:
Factors to influence blowdown rate:
- Surface blowdown valve: This is supposed to be the best
choice for blowdown valves. It is used for removing dissolved
solids. It helps in removing solids at those points where they are
- Bottom blowdown valve: This is another type of valve for
controlling dissolved solids. The function of this type of valve is
to remove sludge which gathers in the bottom of the boiler.
Uses of blowdown valves:
- The size of the blowdown line.
- The boiler pressure.
- The length of the blowdown line between the blowdown vessel and
Certain uses of these valves are as follows:
- These valves are appropriate for use with air compressors.
- They are used to help in the removal of slug and unwanted
materials after cleaning the pipes.
- Blow down valves are found on the water feeders.
- They are also used to lower water cut-offs.
- They can control the concentration of solids in the boiler.
The points mentioned below will be a guide for the buyers: