A valve assembly may have an inlet configured to receive pressurized fluid, a first port, a diaphragm comprising a first side and an opposing second side, a first one-way valve disposed so as to allow fluid to flow from the inlet to the first side of the diaphragm, and a second one-way valve disposed so as to allow fluid to flow from the inlet to the first port. The first side of the diaphragm may be in fluid communication with the first port and with atmosphere, and the second side may be in fluid communication with the first one-way valve, the diaphragm sealing the first port from the first one-way valve and from atmosphere, such that when fluid pressure in the first port exceeds the fluid pressure at the first valve, the diaphragm may flex to allow fluid to flow from the first port to atmosphere.