Community Research and Development Information Service - CORDIS


There is a difference between the true discharge coefficient CD for liquid flow through a safety valve and the more familiar 'coefficient' KD; this difference increases with the orifice-to-inlet diameter ratio. The use of CD or KD depends on whether the relief system design calculations are carried out in terms of static pressures or total pressures. Confusion between CD and KD could result in undersizing of valves. These matters involving the relationship between CD and KD are studies. Furthermore, a safety valve model is proposed in which the flow characteristics are described by a discharge coefficient CDn for the valve nozzle and a loss coefficient Kb for the valve body. This two-parameter model permits a more detailed description of the flow than existing models. It is found that, for some valve types, it is important to take account of the area change between the inlet and the orifice. The implications of this for sizing and stability are studied.

Additional information

Authors: MORRIS S D, JRC Ispra (IT)
Bibliographic Reference: Article: Journal of Loss Prevention in the Processing Industries
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