Birchmeier sprayer parts 14.5-psi constant flow valve for Flox 2.5-gal. (Item # 151246) and Iris 4-gal. (Item # 151247) backpack sprayers. Birchmeier sprayer valve will automatically maintain a constant flow at 14.5 psi, resulting in fewer pumping strokes and easier pumping. The 14.5-psi Birchmeier sprayer valve is designed for herbicide application at low pressure where spray drift is a concern.