Oilers/Plant Tenders (HHC) Civil Service Practice Exam

What equipment is commonly used to separate heavy liquids from lighter liquids?

1. Filtration unit

2. Distillation apparatus

3. Centrifuge

4. Decanter

The correct answer is: Centrifuge

The correct choice for separating heavy liquids from lighter liquids is a decanter. A decanter is specifically designed to utilize gravity to separate different phases of liquid based on their densities. In the case of a mixture of heavy and light liquids, the components will stratify, allowing for the denser liquid to settle at the bottom while the lighter liquid rises to the top. The decanter can then be used to draw off each phase. While a centrifuge can also be used for separation based on density, it operates by spinning the mixture at high speeds to create a strong centrifugal force, which causes the liquids to separate more rapidly than gravity alone would allow. However, a decanter is more straightforward for lighter and heavier liquid separation in many applications, making it the most appropriate choice. Filtration units are mainly intended for solid-liquid separations and are not suitable for separating liquids of differing densities. A distillation apparatus is used primarily to separate liquids based on differences in boiling points rather than density, making it less applicable for this particular separation task.