Spring Operated Valve and Pilot Operated Valve

[cap_pelela]

which is the diferences between a Spring Operated Valve and Pilot Operated Valve?
when use it each one?

Regard!

[janakiraman.malliga]

[IMG]


* Relief valve (RV): automatic system that is actuated by static pressure in a liquid-filled vessel. It specifically opens proportionally with increasing pressure.

* Safety valve (SV): automatic system that relieves the static pressure on a gas. It usually opens completely, accompanied by a popping sound.

* Safety relief valve (SRV): automatic system that relieves by static pressure on both gas and liquid.

* Pilot-operated safety relief valve (POSRV): automatic system that relieves by remote command from a pilot on which the static pressure (from equipment to protect) is connected.

* Low pressure safety valve (LPSV): automatic system that relieves static pressure on a gas. Used when difference between vessel pressure and the ambient atmospheric pressure is small.

* Vacuum pressure safety valve (VPSV): automatic system that relieves static pressure on a gas. Used when the pressure difference between the vessel pressure and the ambient pressure is small, negative and near the atmospheric pressure.

* Low and vacuum pressure safety valve (LVPSV): automatic system that relieves static pressure on a gas. The pressure is small, negative or positive and near the atmospheric pressure.


RV, SV and SRV are spring operated (even said spring loaded). LPSV and VPSV are spring operated or weight loaded.


spring loaded safety valve
seat tightness up to
set pressure
– higher operating to
set pressure ratios
– small overpressure
and blowdown
– fast and complete valve
opening
– low medium loss

pilot operated safety valve
– small structural size,
low weight
– higher seat tightness
– small overpressure and
blowdown
– higher set pressures
– higher operating to
set pressure ratios
– higher back pressures
– adjustable blowdown

[cap_pelela]

thank for answer! it`s very usefull to me!
Regards from Argentina.