1:

In a gas pipeline a mixture of hydrogen in air is transported. Usually, the hydrogen content of
the gas is 1 vol%. It is well below the lower explosive limit as a hydrogen / air mixture which is 4 vol% hydrogen.In the gas pipeline a detector is positioned that activates an alarm if the
detects a hydrogen content in the gas of 3 vol% or more. The detector's dynamic behavior may be described as a first order system with gain 1 and time constant 5 seconds.
The flow rate of the gas is constant 1 m3 / second.

In another case, error control led to a hydrogen content slightly above the explosion limit, namely 4.5%.

B) Calculate the amount of explosive gas passing the detector before the alarm sounds, is it higher at 7% or 4.5% hydrogen gas.

Incorrect operation will normally be discovered before the alarm goes off.
We have a situation where the hydrogen content rises suddenly from 1 to 7% and shortly again suddenly decreases to 1%.

C) What is the largest amount of explosive gas (in m3) that can get transported through the pipeline without the alarm being activated?

Problem 2:

In a liquid level vessel with laminar flow the outlet valve is fully open. Its resistance is R0.
The inlet and the outlet Qi Qu is constant for a long time, as os the level.
Suddenly the valve is turned, but is not closed completely. The resistance, R, is growing spontaneously
from R0 to R0 + ▲ r.

B) What will be the response of H and Qu when Qi remains constant all the time?

N.B .: The system is nonlinear!

Problem 3:

A liquid level control system is controlled in two different ways: with a control valve that controls a flow of liquid into the tank (Figure 1)

or with a valve which controls the power out from the tank (Figure 2),

LT is always acting directly. Determine, for each configuration, how a pneumatic proportional controller to work (Direct / Inverse), if the valve is

A) ATO (air-to-open)?
B) ATC (air-to-close)?

The answer must be justified.

ZD LT LC