Correlating a few technical terms 16-01

There are a few technical terms that frequently appear in the papers I write and the formulas I use. These terms include:

If you are going to be messing around with pumps, bearings and mechanical seals, these words are going to have to become a regular part of your vocabulary. In this paper I am going to show you how these words sometimes work together to get us the information we need to both select and troubleshoot centrifugal pumps and mechanical seals. We will start with specific gravity; a measure of the weight of a fluid.

Specific gravity numbers are used to:

Density is a measure of the weight of a fluid. Density is a much better term than specific gravity and should eventually replace it as the most popular term. Density is measured in gm/cm3 or lb/in3

Gravity is used:

Specific Heat determines how hot the product will become with the addition of heat. The specific heat numbers are used to:

Specific speed is a dimensionless number that describes the shape of the pump impeller. We use this number to:

Viscosity is defined as resistance to pouring, with higher viscosity liquids affecting centrifugal pump performance in several ways:

Unfortunately there is no acceptable analytical method of predicting pump performance when the liquid has a viscosity different than water. Many tests have been conducted and the data formulated into charts and nomographs with the result being that your pump performance can be reasonably estimated for liquids of just about any viscosity. Check with your pump manufacturer for his charts.

Rpm or speed is used:

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