A tank $($T$1)$ is used to temporarily store acetone before the acetone will be

subsequently used. Acetone is flowed into tank $($T$1)$ by using a pump $($P$1)$ as

shown in FIGURE Q$3.$ It is important to ensure that there is no excessive feed of

acetone into the tank which will result in overflow of the tank $($T$1).$ Hence, high

level control system, which consists of level indicating transmitter $($LIT$),$ level

indicating controller $($LIC$),$ flow control valve $($FCV$)$ and alarm, is installed in tank

$($T$1).$ TABLE Q$3$ shows the failures$/$demand data for the safety functions.

Develop an event tree of this system using "excessive feed of acetone into the

tank $($T$1)"$ as the initiating event. If the frequency of excessive feed of acetone

into the tank $($T$1)$ is $35$ occurrence per year, estimate the numbers of overflow of

the tank $($T$1)$ per year.

FIGURE Q$3$: A tank which is equipped with level control system

TABLE Q$3$: Failures$/$demand data