Vapor pressure is another term we will be using. The product's vapor pressure varies with the product's temperature.
Specific gravity plays an important part in all calculations involving liquid.
You have to be familiar with this term. You need to understand how the liquid's velocity affects its pressure or head. You have to be able to calculate the head loss through piping, valves and fittings. You must know the difference between gage pressure and absolute pressure. Vacuum is often a part of the calculations so you are going to have to be familiar with the terms we use to describe vacuum.