CHAPTER 9 Flashcards
it is the valve opens based on the pressure drop across the valve seat?
conventional spring-operated relief
it is a the bellows on the backside of the valve seat ensures that the pressure on that side of
the seat is always atmospheric
balanced-bellows
it is a specially designed to rupture at a specified relief set pressure
Rupture discs
Safety valves pop open when the pressure exceeds the set pressure. This is accomplished by
using a discharge nozzle that directs high-velocity material toward the valve seat.
The safety valve
The relief valve (liquid only) begins to open at the set pressure.
The relief valve
relief valves for liquids and as safety valves for gases
The safety relief valve
Every step in this method is critical to the development of a safe design; an error in any
step of this procedure can result in catastrophic failures
Relief method
this is commonly used within the chemical industry to describe reliefs are
given in the following paragraphs.
Defintions
The procedure for specifying the location review of every unit operation in the process and of
every process operating step.
Location of Relief
In engineering terms the type of relief device is specified on the basis of the details of the
relief system, process conditions, and physical properties of the relieved fluid.
Relief Types and Characteristics
The gauge pressure during normal service, usually 10% below the
MAWP.
Operating Pressure
The pressure increase over the MAWP of a vessel during the relief process.
It is expressed as a percentage of the MAWP
accumulation
The pressure increase in the vessel over the set pressure during the
relieving process
Overpressure
The pressure difference between the relief set pressure and the relief reseating
pressure. It is expressed as a percentage of the set pressure.
Blowdown
The pressure at the outlet of the relief device during the relief process resulting from
pressure in the discharge system.
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