What is a Backflow?
Backflow Prevention Devices
For the EZFLO hose and tap models attached to your tap (bib), the minimum backflow prevention device is a vacuum breaker which retails for approx. $14.- and are available from your local plumber shop and is simply fitted, by you, directly onto your tap before fitting the EZFLO connector.
Vacuum breakers can be purchased direct from EZFLO and be packaged with your new unit.
Backflow protection is required when using any Main line fertigation device directly attached to your Town water main. If your contractor says it is not needed or glosses over the issue, be concerned and seek another opinion. There are a number of backflow prevention devices used with irrigation systems, but only two should be used with an EZ-FLO main-line system; an RPZ (Reduced Pressure Zone) or a PVB (Pressure Vacuum Breaker).
All EZ-FLO main line unit installations, must have the appropriate backflow prevention device installed.
An RPZ is a mechanical backflow preventer that consists of two independently acting, spring-loaded check valves with a hydraulically operating, mechanically independent, spring-loaded pressure differential relief valve between the check valves and below the first check valve.
It includes shutoff valves at each end of the assembly and is equipped with test cocks. An RPZ is effective against backpressure backflow and backsiphonage and may be used to isolate health or non-health hazards.
A PVB is a mechanical backflow preventer that consists of an independently acting, spring-loaded check valve and an independently acting, spring-loaded, air inlet valve on the discharge side of the check valve. It includes shutoff valves at each end of the assembly and is equipped with test cocks. A PVB may be used to isolate health or non-health hazards but is effective against backsiphonage only.”
PVBs are not appropriate for hilly landscapes where there are irrigation zones with elevations higher than the PVB installation since it will not protect against backpressure. An RP should be used in these conditions.
Our systems are classified as aspiration devices. Although our fertigation systems are sometimes termed “injection” devices, they actually are not an "injector" in the technical sense of the word because they operate under ambient water pressure present in the irrigation system and cannot add any additional backpressure to the system like other "injectors".
Backflow prevention devices that may be used is a Pressure Vacuum Breaker (PVB). Of course it is also acceptable to use a more protective device such as a Reduced Pressure-High Hazard Zone (RPZ) backflow preventer if required by local code. Therefore there are two backflow prevention devices that are acceptable in use with an EZ-FLO Main Line system according to the Foundation, either an RPZ or a PVB.
Follow all local codes when installing an EZ-FLO unit or any other fertigation device!
Additional Protection Engineered into an EZ-FLO Fertigation Device
Even if a backflow condition were to occur in an irrigation system and the backflow prevention device failed, an EZ-FLO unit is designed to air-lock when flow reverses through the unit. At most, there will be up to 1/8 of a teaspoon of fertiliser that can be introduced in the inlet side of the water line before the unit stops proportioning. This means that only that amount, and the already diluted amount in the irrigation lines, could backflow.
Since EZ-FLO main-line units proportion at a maximum rate of 400 to 1 on the fast setting (15,000 to 1 on the slow setting) even if the residual of nutrient laden irrigation water in the irrigation system were to backflow, the concentration level of fertilizer or supplements in the main line water is so small that it presents only a miniscule risk. This of course assumes that the primary backflow prevention device has also failed, which is also highly unlikely. Finally we have always recommend that only non-hazardous fertilizers and supplements be used with our systems, further reducing the risk for dangerous contamination. With the introduction of natural and organic products in 2006 and the increasing availability of food grade fertilizers in the market, we have further reduced the potential for any hazardous health effects from using fertigation.
If you have any question about backflow prevention and EZ-FLO fertigation units, please contact Us for more information. We have presented our systems to many governmental authorities concerned with backflow prevention and we have been able to help educate them on the issue of backflow prevention when using fertigation and why it need not be a major concern when proper backflow prevention controls are in place.
In light of the real risks to the environment through the overuse of traditional broadcast granular fertilizers and pesticides that are eliminated or drastically reduced when using an EZ-FLO fertigation system, EZ-FLO represents not a real risk but a risk reduction! Most governmental decision makers appreciate learning more about the potential reduction in fertilizer needed since they are also responsible for reducing Non-Point Source Pollution and for reducing water usage in their communities.
For more information on significant negative effects from fertiliser runoff and from pesticide use and how you can the reduce the amount of fertiliser applied when using EZ-FLO fertigation, see our Whitepaper.
To place and order or for more information please call (07) 4725 6088 or send an email or request a quote.