Some embodiments include a valve assembly with a metering seal including a main channel including regions with a first diameter and regions with a second diameter, where the first diameter is smaller than the second diameter. Some embodiments include a stem positioned in the metering seal extending from at least a first end of the metering seal to a second end of the metering seal. In some embodiments, the stem has a fluted section positioned between two non-fluted sections, where the diameter of stem in the fluted section is smaller than the diameter of the stem in the non-fluted sections. Some embodiments include a first and second flow channel extending across at least a partial width of the metering seal, where the first flow channel is positioned at the first end of the metering seal, and the second flow channel is positioned at the second end of the metering seal.