From the transfer function of a liquid manometer it is clear that it is a second order system.

Pascal and atm are two different units used to indicate pressure values.

Flow rate of a fluid in a path is analogous to current flow in a conductor and both can be treated as analogous quantities.

A liquid is said to be in laminar flow if its pressure changes are minimum, otherwise it is said to be in turbulent flow.

pH meter is used for measuring pH value of a liquid, all other devices are used for measuring pressure.

Force is a vector quantity and all other mentioned quantities are scalar quantities, which have magnitude only.

The advantage of pneumatic system is that gases show high compressibility which uses minimum space for a volume same as hydraulic system.

Value of damping factor in liquid manometer is far below one and the system represents under damped system.

Difference in pressure between absolute zero and local atmospheric pressure is known as gauge pressure, whereas differential pressure is the difference of pressure between two medium.

ΔV is the incremental change in volume and ΔP is the incremental change in pressure.