When installing and underground sprinkler system, there are two types of pipe used, PVC ridged pipe and Polyethylene flexible pipe. Poly flexible pipe is suggested for areas that experience freezing ground. In choosing pipe size refer to the information given below. If in doubt, always select the next larger size pipe because larger pipe size will generally improve performance. A common practice is to run larger diameter pipe from your water source to your control valve, then to a central spot in the zone to be watered and then reduce pipe size in branching lines to your sprinkler heads. When making long pipe runs over 100 feet, use one pipe size larger in diameter to reduce pressure losses at the end of the run. IMPORTANT: When choosing pipe sizes, take note that your pipe fittings should be the same size or larger than the control valves to assure proper performance. GALLONS THROUGH PIPE 0-8 GPM: use 3/4" valve, 3/4" PVC pipe or 3/4" Poly pipe 9-12 GPM: use 3/4" valve, 3/4" PVC pipe or 1" Poly pipe 13-20 GPM: use 1" valve, 1" PVC pipe or 1-1/4" Poly pipe 21-35 GPM: use 1" valve, 1-1/4" PVC pipe or 1-1/2" Poly pipe |