Question $3$ Control Valves

$3\mathrm{.}1.$ You are required to recommend the specific flow characteristic for pressure control

system for each of the following scenarios:

a$)$ Gas process, small volume, less than $3$ meters of pipe between control valve and load valve.

$[2]$

b$)$ Gas process, large volume $($process has a receiver, distribution system or transmission line

exceeding $100$ feet of nominal pipe volume$),$ decreasing $P$ with increasing load, $P$ at

maximum load $>20\%$ of minimum load $P.$

c$)$ Gas process, large volume, decreasing $P$ with increasing load, $P$ at maximum load

of minimum load $P.$

$3\mathrm{.}2.$ Make use of the $\%$ of maximum flow vs $\%$ of rated travel diagram to demonstrate the flow

characteristics given in Question $3\mathrm{.}1.$

$3\mathrm{.}3.$ A control valve with an equal percentage inherent characteristic has a maximum $C_v$ of

$1300$ and a rangeability of $40.$

$($a$)$ Calculate the $\%$ changes in the flow for every $10\%$ change in valve lift;

$($b$)$ Calculate the values of $C_v$ corresponding to valve travel from $10\%$ to $100\%$ by step of

$10\%,$ draw a table containing these values.