Quite often I’m asked about running a few extra heads on a zone by contractors who want to reduce a 10-zone system down to an 8-zone system, for example, for various reasons—usually because they are over budget or in a hurry.
The conversation might begin with a statement similar to this:
“I know you’re not supposed to run that many heads on one zone, but I have REALLY great pressure.”
Having great pressure is certainly part of the equation when it comes to having a successful irrigation system, but it’s only a part of the equation.
As a contractor, you’re always concerned with—or should be—providing a quality irrigation system for your customer so that they can tell their neighbor how great it is, thus leading to future opportunities for your business.
The problem with pushing your zones past the recommended capacity is not so much whether it will work initially or not, but what the long-term ramifications of doing so might be.
5 Feet-Per-Second
A quality irrigation system should operate at a velocity of five feet-per-second or less. The effect of exceeding recommended line capacities for your irrigation system is increased velocity.
Velocities can quickly approach 8, 9, or 10 feet-per-second when recommendations are not followed. An increased velocity in your system usually lead to more leaks, fitting failures, rotors wearing out more quickly, and a number of other problems—including a negative impact on your customer’s level of satisfaction.
Irrigation systems with velocities above the recommendation range will leave the customer frustrated having to do self-repairs, spending more money on professional repairs, or even making several callbacks while the system is still under warranty.
Is this something that is really worth the benefits gained from overloading a zone?
Velocity charts are easy to obtain, and can be found quickly in manufacturer catalogs.
At the end of the day, you will have fewer headaches and more satisfied customers when you work within the boundaries of recommended velocities.