An improved metering apparatus is provided for use with a foam dispenser that disperses beads of foam after mixing streams of two foam components together. The dispenser has a pair of seal passages formed in a body portion of the dispenser and a spool valve rotated mounted in the body portion. The spool valve has a pair of flow passages formed in it that can be rotated into mating alignment with the seal passages formed in the dispenser body. The spool valve flow passages have circular cross-sections while the seal passages have non-circular cross-sections, and preferably triangular cross-sections.