Agricultural ammonia tool bar throttle valve

A simple ammonia tool bar throttle valve is disclosed which is primarily for use with those systems which will utilize a stripper pump unit to increase the ammonia system pressure prior to the metering devices. The ammonia tool bar throttle receives the metered ammonia at a greater pressure than that of the system storage tank, and enters a lower chamber where it crosses a filter before exiting the unit across a throttle orifice which is throttled by the action of an aluminum throttle diaphragm which separates the lower chamber from a control chamber. The aluminum throttle diaphragm is positioned to maintain the desired mass flow by the forces of a separately regulated ammonia control fluid which is throttled to the control chamber before being bled back to the storage tank across an orifice.