Controlled safety pressure releive system 1

[Raai2015]

As subject, most of us knows , conventional springloaded safety valve has checknut in the bonnet which will keep the spring during operation , when it reaches the set pressure , spring will be compressed against the checknut by steam and releive it.
In the Pneumatic, air pressure will act on the diaphragm on both side, when it reaches the set pressure , lift air pressure is activated and relieves the pressure. Queries are,
1. How the construction of spring on the pneumatic operation , specifically cecknut portion? Because i received the offer which says pneumatic supplementary safety valve but it has the check nut.
2. Basic clarification. Pneumatic air is supplied with 5 bar. But the set pressure is 92bar . How does pneumatic air with 5 bar loading and lifting the 92 bar steam?

 

[The Obturator]

Please clarify what you mean by "Checknut". In a conventional spring operated SRV there is an adjusting bolt forced down onto the spring and secured by a nut. This is usually outside the bonnet. I do not understand what you refer to. Generally a CSPRS is a lift/closing device to assist the sprin operated valve dependant on application. In case of CSPRS failure, the SRV would/should work as a spring operated SRV. 5 - 7 plant air feed is normal for these devices. There is also yuse of pressure regulators and sizing of actuator area to consider. Cannot comment more as no further detail from you.

Per ISO, only the term Safety Valve is used regardless of application or design.

 

[The Obturator]

* 5 - 7 bar

Per ISO, only the term Safety Valve is used regardless of application or design.

 

[Raai2015]

Yeah , i meant the adjusting the boltnut.

In this CPRS - how this adjusting bolt?. As you said for conventional valve we need this for keeping the spring force against steam. But in this power actuated construction how does it works?

 

[The Obturator]

If I now understand your question correctly. You are asking how is the set pressure achieved by the spring as you cannot see an adjusting bolt/nut. I am not intrically familiar with this manufacturers design, but I would get the tension (set pressure) for the spring is contained with either a bolt that has not been made clear on the generic diagram, or by a custom engineered sleeve of a length to obtain the set pressure. It does not matter, what is important for the CSPRS design is that "pulling" (opening valve) and "pushing" (closing) is achievable from the pressure transmission component, that is, the Spindle, which is attached to the actuator. Consider this unit is 2 items. 1 - a spring operated safety valve with 2. auxilary control device - actuator to control opening and closing of the SRV which the SRV cannot achieve on its own. Suggest you speak to manufacturer for more detail as this CSPRS has been specified for a reason.

Per ISO, only the term Safety Valve is used regardless of application or design.

 

[The Obturator]

NB. I also notice 1 pressure line to top of actuator (no line under actuator for lifting). If that is the case, this CSPRS has been configured to keep valve seats tight only. Again, you need to speak to manufacturer.

Per ISO, only the term Safety Valve is used regardless of application or design.