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# Pilot Operated Safety Valves in Liquid Systems

The minimum discharge area of a pilot operated relief safety valve in a liquid system can be calculated as

A = q SG1/2 / (36.81 Kvisc dp1/2)                                     (1)

where

A = discharge area (Square Inches)

q = relieving capacity (Gallons per Minute)

SG = Specific Gravity of the fluid

Kvisc = correction factor due to velocity - 1.0 for most water systems

dp = differential pressure - set pressure (psig) + over pressure (psig) - back pressure (psig)

## Related Topics

### • Design of Control and Safety Valves

Sizing and dimensions of control valves & equipment in steam and condensate systems.

### • Pressure Ratings of Pipes and Fittings

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

## Related Documents

### API - Valve Standards

An overview of the American Petroleum Institute - API - valve standards.

### BSi - British Standard Valves

An overview of BSi - British Standard institute valve standards.

### DIN - Valve Standards

An overview of DIN - Deutsches Institut für Normung - valve standards.

### Factors of Safety - FOS

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

### Heating Systems - Safety Valves Size vs. Boiler Power

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### High Pressure Steam Systems - Safety Valve Capacities

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

### Low Pressure Steam Safety Valves - Capacities

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

### 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

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### 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.

### Steam Safety Valves - Installation Guide

Guidelines to safety steam valves installation.

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