Explosion vent vs Pressure relief device 1

[k0412d]

Hello all,

I remember reading a book where was made explicit the definition of the explosion vent and Pressure relief device.
From what I remember one would stay open once been activated one the other would close.
Since I fail to get the hand on that book I wondered whether I remembered right at all... could someone shed the light on me?

And I really would like to have your opinion on when and why to install this mechanism.

Thank you very much.

 

[davidbeach]

Wow, what an unanswerable question.

How about starting out with what the application is. Then, how about where in the world you might be as terminology can differ from place to place. When and why to install most anything comes down to code requirements or applicable standards or engineering judgment and you haven't provided enough to know any of those things.

 

[k0412d]

Ok you right,
For the first 'how about' : it's true I forgot to tell that it was about transformer, sorry.

For the 2nd 'how about' :
I agree that terminology differs from place, standards manufacturer ect...
But it does mean that there is no answer, just that it is not that simple.
In that case I though there was a strict (or accepted) definition, my bad.

 

[prc]

In the early days, transformers were provided with an explosion vent.It was a thin bakelite plate mounted on a pipe end projecting above the conservtaor. When internal pressure exceeded, it used to break open spilling out oil and excess [pressure.Then you have to change the diaphragm with a new one.

Later spring operated pressure relief device came in to.It is a diaphragm pressed down by a stainless steel spring,mounted over the tank top.When pressure exceeds,it will open out and automatically close when pressure comes down.

 

[RRaghunath]

k0412d,
When it comes to transformers, your understanding about Explosion vent and the PRD is the same as I know.
Explosion vent is a diaphragm at the end of a large dia vent pipe that is expected to rupture and release the pressure from inside the transformer tank. Thus, it is not reusable.
PRD is a spring loaded valve that lifts up at the calibrated pressure and sits back once the pressure is released. This comes typically with a flag to indicate its operation and a switch whose contact output can be wired in to transformer protection scheme.

 

[ScottyUK]

Don't be under any illusion that either an explosion relief with a bursting disc or a Qualitrol-type PRD will prevent a catastrophic rupture of the tank if a major internal fault occurs: they won't.


----------------------------------

If we learn from our mistakes I'm getting a great education!

 

[k0412d]

thank you for your responses.

 

[RRaghunath]

You are right, ScottyUK. The tank rupture still can take place depending on various factors.
The vent/prd is located in such a way that the chances of tank rupture are minimised. That is the reason why large transformers are provided with more than one PRD.