For only a few cents more you can have a dripper that delivers the same flow rate for all pressures between 8 and 45psi. Or in other words the elevation could vary by as much as 100 feet and all drippers would put out the same flow (assuming friction loss in the pipe is not more than 10psi.) (See non pressure compensating drippers)
Not only is elevation change a reason to use these, but also zone pressures. If the zones don't have the exact same pressure setting, the flow will still be the same out of each dripper in different zones (assuming you used the same dripper) because of the pressure compensating feature.
Most of the PC Drippers are continuous self-flushing and some have a "No Drip Shutoff" feature. They don't sit there and drip after you shut the system off because and internal check valve closes at low pressure (about 6psi.) The tubing stays full of water and doesn't drain all the water at the low spot of the system. Look for the CNL featured drippers. High tech... Way cool...
Help is just a click away, try our Pressure Compensating Drippers product finder.
Techflow 0.5GPH Self-Cleaning Drippers w/Check Valve
Planters, Pots, sub-surface or on-surface. Techflow self cleaning drippers can be used in a wide variety of applications with reliable results.
PCDj 0.5GPH Self-Flushing Drippers w/Check Valve
Check Valve feature is the most important breakthrough in low volume technology since the introduction of dripperline. Select this item for 1/2 gallon per hour performance.
PCDj 1.0GPH Self-Flushing Drippers w/Check Valve
Also with Netafim\'s Check Valve feature, this top of the line low volume dripper provides 1 gallon per hour flow rate.
PCDj 2.0GPH Self-Flushing Drippers w/Check Valve
This dripper regulates flow and provides continuous self-cleaning action during operation at a flow rate of 2 gallons per hour.
Techflow 1.0GPH Self-Cleaning Drippers w/Check Valve
Low CNL Techflow self cleaning drippers can be used with wide spaced planting equally as well as pots or planters.
Techflow 2.0GPH Self-Cleaning Drippers w/Check Valve
Self-cleaning anti-siphon performance at a flow rate of 2.0 GPH
Techflow 6.0GPH Self-Cleaning Drippers w/Check Valve
A whopping 6.0GPH flow rate for larger applications.