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Heating Systems - Safety Valves Size vs. Boiler Power

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Fired pressure vessels shall be fitted with safety relieving devices with sufficient capacity to relieve all vapor that may be generated in the vessels during normal operation. The safety relieving devices shall be fitted with proper controls to ensure safe operation.

Heating Systems - Safety Valves vs. Boiler Power
Boiler rating
Minimum clear bore
of safety valves and vents
275 1 x 20
350 1 x 25
440 1 x 32
530 1 x 40
880 2 x 40
1500 80 to 150

Note! Check domestic regulations - Safety Valve Standards

  • 1 kW = 3412 Btu/h
  • 1 inch = 25.4 mm

Safety valves should be removed at least once each year for inspection and cleaning of any deposits that might affect their operation.

To eliminate the necessity of shutting the system down for the inspection, a three-way stop valve may be installed under 2 safety valves, each with the required relieving capacity, installed so that both safety valves cannot be closed off from the vaporizer at the same time. Alternatively may 2 or more separate safety valves be installed with individual shutoff valves, in which case the shutoff valve stems is mechanically interconnected in a manner that allow full required flow capacity at all times.

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Related Topics

Heating Systems

Design of heating systems - capacities and design of boilers, pipelines, heat exchangers, expansion systems and more.

International Valve Standards

International valve standards for piping systems.

Pressure Ratings of Pipes and Fittings

Pressure ratings of pipes and tubes and their fittings - carbon steel , stainless steel, plastic, copper and more.

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Factors of Safety - FOS

Factors of Safety - FOS - are important in engineering designs.

Heating System Flow Rates

Calculate flow rates in heating systems.

High Pressure Steam Systems - Safety Valve Capacities

Sizing safety valves according boiler output power in high pressure systems (kW and Btu/hr)

Hot Water Heating Systems - Online Design Application

Free online design tool for designing hot water heating systems - metric units.

Hot Water Heating Systems - Online Design Application, Imperial Units

Online design tool for hot water heating systems.

Hot Water Heating Systems - Pressure Loss in Steel Pipes

Pressure loss nomogram for hot water steel pipes.

Hot-Water Heating Systems - Classification

Hot-water heating systems can be classified by temperature and pressure.

Low Pressure Steam Safety Valves - Capacities

Sizing safety valves after boiler output power in low pressure systems (kW and Btu/hr).

Pilot Operated Safety Valves in Liquid Systems

Calculate pilot operated relief valves in liquid systems.

Relief Valves - Length of Vent Pipes

Calculate length of safety valves vent pipes.

Safety Relief Valves - Capacity vs. Pressure

Maximum safety valve free air relief capacity.

Safety Signals - Recommended Colors

American National Standards Institutes schedule for safety colors marking physical hazards.

Safety Valve Standards

The most common used safety valve standards in Germany, UK, USA, France, Japan, Australia and Europe.

Safety Valves in Gas and Vapor Systems

Calculating relief valves in gas and vapor systems.

Safety Valves in Saturated Steam Systems

Calculate safety valves in saturated steam systems

Spring Operated Safety Valves in Liquid Systems

Calculate spring operated relief valves in liquid systems.

Valve Type Classifications

Categories of valves.

Valves Types - Operating Size Ranges

Types of valves and their typical operating sizes.

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