Blowdown Vessels by GMSRiverside Works • Egmont Street • Mossley • OL5 9NE
Tel. 01457 835700 • Fax. 01457 832700

Blowdown Vessels

Blowdown Vessels

BV blow down vessels are designed and manufactured fully in accordance with the latest PD5500 Category III standards, inspected during design and manufacture by an independent insurance company and supplied complete with a data dossier. They also comply fully with the European Pressure Equipment Directive 97/23/EC.

Background Information

When a steam boiler evaporates water the dissolved minerals in the remaining boiler water are concentrated. To prevent the concentration becoming excessive and causing damage to the boiler some of the water is “blown down” from the boiler periodically and replaced with fresh water. The blow down water loses pressure rapidly, resulting in the evolution of flash steam. This mixture of steam and hot water is a potential hazard. It is not permissible to drain water to public sewers above 43°C so the blow down water must be safely contained and allowed to cool first. The BV Blow down Vessel is designed to do this.


Boiler blow down installations must comply with the Pressure Systems and Transportable Gas Containers Regulations 1989 (“Pressure Systems Regulations”)(HMSO). Recommendations on design of boiler installations are given in BS806 and PM60 (available from BSI and HMSO respectively). Following these recommendations will satisfy most of the requirements of the Pressure Systems Regulations. BV blow down vessels comply with BS806 and PM60. Also, the HSE Guidance Note PM5 (available from HMSO) states various requirements for the system design. Blow down vessels must have a minimum design pressure of 7 BarG or 25% of boiler pressure, whichever is the greater. BV blow down vessels have a standard design pressure 7 BarG - higher on request.

Ancillaries Supplied As Standard

  • Vent Head - Stainless Steel, Screwed or Flanged
  • Cooling System - Direct Acting Valve & Sensor
  • Inlet Manifolds (Three off) - Supplied Complete With Isolation & Check Valves
Design & Manufacturing Details:
Design Code: PD5500 Category 3
CE Marked
Complies with SI 1999/2001 Pressure Equipment Directive
Complies with HSE Guidance Note PM60

Material: Carbon Steel
Design Pressure: 7 BarG
Design Temperature: 171°C
Higher Pressure & Temperature Units on Request

The outlet connection has an internal dip-tube to allow blow down to cool before disposal. If disposal temperature exceeds 43°C, water cooling may be needed.

For further information, please visit our main website at
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