The density or weight of a given volume of liquid is determined by using a mud balance. The balance beam is graduated and permits accurate measurements to within 0.01g/cm³ ,0.1lb/gal , 0.51b/cu ft, 51b/sq in/1000ft. The balance is constructed so that the fixed volume cup at one end of the beam is balanced by a fixed counterweight at the opposite end, with a sliding weight rider free to move along the graduated scale. A level bubble mounted on the beam indicates when the system is in balance. On one side are scales for measuring density in specific gravity (g/cm³) and pounds per cubic foot(1b/cu ft),on the other side are scales in pounds per gallon (lb/gal)and pounds per square inch per 1,000 feet(1b/sq in/1000ft). Take the reading from the side of the rider nearest the balance cup.

The balance consists of a graduated balance beam with cup, lid cap, and a base with fulcrum. See Figure 3-1. The beam has four graduated scales(two per side):

• Pounds per gallon

• Specific gravity

• pounds per cubic foot

• pounds per square inch per 1,000 feet

This feature makes it possible to choose the appropriate density units.

The balance beam also has a sliding weight (rider) that moves along the graduated scale on the beam and a bubble level that indicates when it is balanced. The indention on the beam sits securely on the knife edge of the fulcrum.