Group 1: Function and Design of Safety Valves
– Safety valves act as fail-safes, automatically releasing substances when pressure or temperature exceeds limits.
– Early designs included weight-retained steam valves, which were prone to tampering and accidental release.
– John Ramsbottom invented a tamper-proof spring safety valve in 1856, enhancing safety on railways.
– Safety valves protect equipment like pressure vessels and heat exchangers, but are limited to compressible fluid applications.
– Two protection types exist: thermal protection (small valves for liquid expansion) and flow protection (larger valves for gas/liquid discharge).
Group 2: Technical Terminology and Types of Safety Valves
– Pressure Relief Valve (PRV) and Pressure Safety Valve (PSV) are generic terms; PSVs include manual emergency levers.
– Relief Valve (RV) opens automatically with increasing liquid pressure; Safety Valve (SV) opens completely with gas pressure.
– Safety Relief Valve (SRV) relieves pressure for both gas and liquid; Pilot-Operated Safety Relief Valve (POSRV) operates remotely.
– Low Pressure Safety Valve (LPSV) and Vacuum Pressure Safety Valve (VPSV) manage small pressure differences.
– Diverse types of safety valves exist for various applications, including Vacuum Safety Valves, Thermal Relief Valves, and High Integrity Pressure Protection Systems (HIPPS).
Group 3: Historical Development and Innovations in Safety Valves
– Denis Papin invented the first safety valve for his steam digester, functioning as an early pressure cooker.
– The lever arm design allowed pressure regulation using a smaller weight, significant for steam pump applications.
– Historical incidents, like the 1803 Greenwich explosion, highlighted the need for improved safety measures.
– Innovations included the introduction of pairs of safety valves by Trevithick in 1806 and lightweight spring valves by Timothy Hackworth in 1828.
– The evolution of safety valves has focused on reliability and automation to prevent human error, with designs like Ramsbottom Safety Valves and Naylor valves enhancing performance.
Group 4: Legal, Code Requirements, and Standards in Industry
– Industries must legally protect pressure vessels with relief valves in most countries.
– Compliance with design codes provided by ASME, API, and ISO (ISO 4126) is mandatory.
– Design standards include specifications for relief valves and inspection/testing schedules.
– Hygienic safety valves are required in food, drinks, cosmetics, and pharmaceuticals industries, with common materials including stainless steel.
– Safety valve sizing guidelines are outlined in the ASME Boiler & Pressure Vessel Code, and API 520-1 provides standards for pressure-relieving device sizing.
Group 5: Safety Features and Related Valves
– Pressure cookers feature safety mechanisms, including two safety valves: a weight nozzle and an ejected rubber grommet, along with safety interlocks to prevent lid removal under pressure.
– Safety valves play a crucial role in preventing structural damage in residential settings, particularly in water heaters, which require T&P valves to prevent disasters from thermostat failures.
– Related valves include ball valves, butterfly valves, control valves, and safety shutoff valves, each serving specific functions in flow control and safety.
– Pilot-operated relief valves enhance safety by managing excess pressure, ensuring system integrity. https://en.wikipedia.org/wiki/Safety_valve
