When you're using a drip irrigation system in uneven areas, the emitters can suck in dirt particles when the system shuts off. You can solve this problem easily with the air bleed valves from DripWorks.
Simply insert an air bleed valve at each of the system's high points and you'll be good to go. Each air bleeder valve will automatically open when pressure drops below five psi, letting air enter the line to break any vacuum in the system.
You can also prevent air locks on high points of a mainline with these valves. Choose from 1/2", 3/4" or 1" sizes. Any way you use an air bleed valve, irrigation will become more reliable and hassle-free.