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Metal Mud Balance

Operating Instructions

Introduction

The density or weight of a given volume of liquid is determined by using a mud balance. The arm is graduated and permits accurate measurements to within ±0.1 pounds per gallon or ±0.01 specific gravity. 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.

Components

• 115-00 OFI 4-SCALE MUD BALANCE, MACHINED ARM, COMPLETE WITH CASE

Specification

• 6.5 - 23.0 lbs / gal
• 0.79 - 2.72 specific gravity
• 49 - 172 lbs / ft³
• 340 - 1190 PSI / 1000 ft

Calibration

OFITE mud balances are calibrated at the factory with the lid included in the mud balance kit. However, the balance should be re-calibrated, if necessary, on site. Any time a mud balance lid, or any other part, is replaced, the instrument should be re-calibrated.

1. The calibration of the instrument may be easily checked by measuring the density of fresh water.
2. Fill the cup with fresh water at around 70°F (21°C), and set the rider on 8.3 pounds per gallon or 1.0 specific gravity. Add or remove lead shot from the shotwell until the instrument is in balance.

Procedure

1. Place the mud balance base (preferably in carrying case) on a flat level surface.
2. Measure the temperature of the fluid and record on the appropriate mud report form.
3. Fill the clean, dry cup to the top with the freshly obtained mud sample to be weighed.
4. Place the lid on the cup and set it with a gentle twisting motion. Be sure that some mud is expelled through the hole in the cap as this will ensure the cup is full and also will free any trapped air or gas.
5. Cover the hole in the lid with a finger and wash all mud from the outside of the cup and arm. Then thoroughly dry the entire balance.
6. Place the balance on the knife edge and move the rider along the outside of the arm until the cup and arm are balanced as indicated by the bubble.
7. Read mud weight at the edge of the rider toward the mud cup.
8. Clean and dry the mud balance after each use.

Results

Report the mud weight to the nearest 0.1 pound per gallon, 1.0 pound per cubic foot, 0.01 gram per cubic centimeter (specific gravity) or 10 PSI/1000 ft.

Density Conversions