A mud balance is a device used to measure the density (weight) of drilling fluid. Mud balance consists of a base and graduated arm with cup, lid, knife-edge, rider, built-in spirit level, and a counterweight. A plastic carrying case is provided to hold the balance intact and in it’s working position.
Density is read at the point where the slider-weight sits on the beam at level. A mud balance can calibrated with water or other liquid of known density by adjusting the counter weight. Most balances are not pressurized, but a pressurized mud balance operates in the same manner.