Blowdown valve

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Gestra blow-down valve on a class 50 steam locomotive

A blow-down valve is a valve attached to the lowest point of steam boilers , which is used for the regular discharge of the sludge that forms in the boiler, which consists of water impurities, scale and residues of anti-scale agents. Such a valve can also be used to completely drain a steam boiler for maintenance work or to shut down the system. Blow-down valves always make a contribution to system and personal protection.

Manual blowdown valves

With the manual blowdown valves, the valve is opened with a hand lever. The sudden opening, which lasts 2–3 seconds, creates a “ negative pressure ” at the bottom of the boiler, which carries away the sludge on the bottom of the boiler. After that, only boiler water is discharged, which is controlled via the blowdown . A special construction was chosen in order to break up solids contained in the boiler sludge due to operational reasons. The cone is installed from below, i.e. H. the closing forces of the closing spring and the boiler pressure are added up.

Automatic blowdown valves

Blow-down valve with diaphragm drive

In the case of the automatic blow-down valves, the valve is suddenly opened by means of a pneumatic diaphragm drive, which is controlled by a blow-down program control with an integrated solenoid valve. Both compressed air and pressurized water can be used as the control medium.

application

Blow-down valves are characterized by:

  • Optimized blowdown effect
  • Insensitivity to water hammer
  • Integrated sampling
  • additional wear protection, even with large throughputs
  • high reliability, long service life
  • quick and easy assembly
  • Consistent implementation of occupational safety by protecting against interference with moving parts

This makes their preferred areas of application:

  • Shell boilers (land systems, steam locomotives, ocean-going vessels, etc.)
  • Waste heat boiler
  • Pure steam generator

Automatic blowdown valves are used in particular in systems that are operated idle.

literature

  • GESTRA AG Bremen: GESTRA brochure Equipment of energy centers
  • Leopold Niederstrasser: Guide for the steam locomotive service. 9. unchangeable Edition 1959. (Reprint: Verkehrswwissenschaftl. Lehrmittelges., Kassel 1979, ISBN 3-921700-26-4 )