Drilling Fluid: Mud Weight Density "mud weight"  is a measurement of fluid weight per unit of volume, and is reported as pounds per gallon, pounds per cubic foot, grams per cubic foot, grams per cubic centimetre, kilograms per cubic centimetre, or as Specific Gravity (sg) gms/cm3. The primary reason of monitoring and controlling density is to control and contain formation pressures and minimize loss of returns, Improve drilling/penetration rates Reduce formation/aquifer damage and Improve hole stability The instruments used for this test procedure is the mud balance an extremely simple but affective instruments that has seen little change over the years. Ideal for field use. Base and graduated arm with cup, lid, knife edge, rider, built-in spirit level, and counter-weight are supplied in a long oblong case about 18 inc long. inside the casing you will fine the pivot attached to the base and a packet of very small beads "weight" Most are synchronized by the manufacture but should be tested at the location using the local water. It consists of a fixed-volume mud cup with a lid on one end of a graduated beam and a counterweight on the other end. A slider-weight can be moved along the beam, and a bubble indicates when the beam is level.  Graduated in lb/gal (6-24), lb/sq in/1000 ft of depth (310-1250), lb/cu ft (45-180), and specific gravity (.72-2.88).  A plastic carrying case holds the balance intact and in working position. Density is read at the point where the slider-weight sits on the beam at level. Accuracy of mud density should be within +/- 0.1 lbm/gal (+/- 0.01 g/cm3). A mud balance can calibrated with water or other liquid of known density by adjusting the counter weight. An outstanding advantage of this balance is the fact that the temperature of the drilling mud does not materially affect the accuracy of readings. Most balances are not pressurized, but a pressurized mud balance operates in the same manner. To use: Clean and dry the balance, check there is no congealed or solid are stuck to the bottom or inside the cup. Fill a mud jug with drilling fluid making sure the fluid come directly from the source you are testing and that the fluid has not been allow to sit. Normally taken from the mud cup after the viscosity has been taken. Fill the mud chamber letting it over flow. Dip the lid in the fluid then lightly place the lid onto the cup and press home. any excess fluid should be discharged from the weep hole in the top of the cup. With the cup full wash of any excess fluid from the balance and wipe dry. place the balance on pivot and slide the counterbalance until the bubble is centre. read the desired weight. from the  graduated arm record the weight to the work sheet. Testing the equipment is accurate: Periodically the balance should be tested for accuracy. This can be done in the field and cost nothing. The balance is correct when spirit level bubble is centre and the slide indicator is at 8.33 ppg or 1 specific gravity There is a line marked. The test is as for any fluid and would normally be carried out using fresh water but can be done using any fluid of a know weight. Any adjustment needed can be done using the weights supplied using the small cap screw at the end of the arm by adding or subtracting a given amount of weights