Samana vayu oversees agni, the fire of purification. The energy force of samana vayu is thought to occur in a spiraling motion. In addition, the manipura chakra is associated with this vayu and processes all that the body consumes: food, thoughts, emotions and breath. This internal fire (agni) is believed to be burning (and processing all that is taken in) correctly when prana and apana unite in the samana vayu.
Many yogis seek to balance this vayu through pranayama practice. During pranayama, matching the length of both inhales and exhales causes prana to meet apana. In addition, yogis can help balance the samana vayu by ensuring good digestive health through a healthy diet.