The success of the MP Rotator spawned the development of other MSMT nozzles.
PHOTO BY HUNTER INDUSTRIES.
As with most things in life, irrigation sprinklers and rotors continue to change. Manufacturers are continually trying to improve their products and introduce innovations. Over the last several years there have been a number of innovations in sprinklers and their nozzles. It is good to know that manufacturers are always looking to improve their products and not settle for the status quo, but looking for a competitive advantage may be more the case.
At the end of 2001, Walla Walla Sprinkler introduced the MP Rotator nozzle to the landscape irrigation market. The MP Rotator was something different with its lower precipitation rates, multiple-stream multiple-trajectory (MSMT) concept and its ability to fit on a spray body, either male or female. For many years, the MP Rotator was the only nozzle of this kind on the market. Over the last few years the other major manufacturers have introduced their own version of an MSMT , there are four different manufacturers of MSMT nozzles on the market and each has unique capabilities while also having a lot in common.
When looking at MSMT nozzles, familiarize yourself not only with the similarities - distance of throw, operating pressure and flow - but also with the differences, such as ease of adjustment, rotating mechanisms and how they match precipitate with changes to either arc or distance. Some MSMT nozzles adjust arc over a certain range while others are fixed arc or variable arc nozzles (VAN). MSMT nozzles are a great alternative to spray sprinklers in some applications due to their lower flow requirements and hence lower precipitation rates.
Pressure-regulated spray sprinkler bodies have been on the market for decades and are a great way to insure sprinklers operate at their intended pressure and don't waste water. Until recently, pressure regulating for rotary sprinklers had to be accomplished at the valve with a pressure-regulating module of some sort. Although not available from many manufacturers, pressure-regulating rotary sprinklers allow control of larger sprinklers that use greater amounts of water and throw greater distances. Where pressure-regulated spray bodies only get to 35 feet or less (depending on the nozzle), the pressure-regulating rotor reaches throws of up to 47 feet. Again, the benefits of pressure regulation include operating the sprinkler at its optimal pressure for the best performance and uniformity, not wasting water and less wear and tear on the nozzle and other sprinkler components.
Manufacturers are always striving to improve the uniformity of their sprinklers and hence their nozzles. Sprinklers that individually or in a group have higher uniformities (how evenly the sprinkler applies water) require lower operating times to apply the needed amount of water to the landscape and therefore save water, energy and money. The last few years have seen many improvements in both spray and rotary sprinkle/nozzle uniformity. As manufacturing technologies, such as plastic molding, have become more sophisticated, it has allowed the manufacturer to get more precise with their design and manufacturing processes. This has resulted in improvements to spray sprinklers that included better edge watering, lower flow rates and higher uniformities.
In many cases today when looking at a manufacturer's catalog, one has the choice between purchasing a regular spray nozzle or a higher uniformity one. Not surprisingly, there is usually also a price difference. Improved uniformity has not been more evident than in recent improvements to several manufacturers' variable arc nozzles. VAN nozzles have always been favorites of irrigation contractors, but not for irrigation designers or water regulators. They have suffered from not holding their adjustment, gaps in coverage, not matching precipitating accurately, using more water and having poor uniformities. New iterations of VAN nozzles have not only addressed these issues, but, in some cases completely eliminated them. Regular VAN nozzles are also now available in a wider range of distances than fixed arc nozzles including 4, 6, 8, 10, 12, 15 and 18 feet depending on the manufacturer you're using.
Plastic technology has allowed for the development of specialized nozzles in addition to low-angle nozzles that have been available in the market for a long time. There are now short-radius nozzles and high-uniformity rotary nozzles. When you looked at a nozzle in the old days, it was simply a circle of some diameter. Now they are of odd shapes and additional outlets beside the main nozzle in some cases, especially as the sprinkler gets larger.
Whereas spray and MSMT nozzles automatically match precipitate, rotary sprinklers do not. The contractor needs to take the time to determine which nozzles need to be installed in the various arced sprinklers (quarter, half, full, etc.) in order to keep them match precipitated. In many cases, the contractor doesn't even bother because it either takes too much time or they do not understand the concept of matched precipitation. Just to make sure we're all on the same page, matched precipitation is the concept of matching the flow (gallons per minute) of the sprinkler to make it proportional to the area it covers.
For example, a zone with a 2.5 GPM half-circle sprinkler would require a 1.25 GPM quarter-circle nozzle and a 5.0 GPM full-circle nozzle to be match precipitated. In the past, the installing contractor would have to pick from a nozzle tree which nozzles were needed to accomplish match precipitation. Today, the manufacturer provides a match precipitated nozzle tree that is in some cases color-coordinated. Instead of looking at the gallonage of each nozzle, the installer just picks the quarter, third, half or full nozzles for the distance of throw that they need from the distances available.
Today's rotary sprinklers pop up higher, normally 4 to 5 inches where in the old days they might have only a 2- to 3-inch pop-up height. Some model rotors are also available in 6-inch or 12-inch pop-up heights. Spray sprinklers are still available in 2-, 3-, 4-, 6- and 12-inch pop-up heights depending on the manufacturer, but some new codes are not allowing pop-up heights less than 4 inches, as they do not clear the turf causing runoff and poor uniformity.
Quality and durability
In the old days sprinkler were made out of brass or bronze and they lasted for as long as 40 years or more. What wore out were the springs and the seals. Today's sprinklers are pretty much all plastic and although they don't last as long as the metal sprinklers of the past, they're durable and much less expensive. Because they are plastic, they also have many more features, such as hundreds of nozzles to select from, pressure regulation, flow shut off and part-circle/full-circle in the same sprinkler.
Today's sprinklers are also subject to more rigorous conditions caused by non-potable water sources that cause plugging, scoring, sticking up and seal degradation. Again, manufacturers have responded with stronger springs, better filters and more robust seals that keep the important parts of the sprinkler from malfunctioning. As plastic mold tolerances are able to be smaller, sprinkler and nozzle quality improves. New quality control equipment has also allowed for better-built products as there are fewer products with defects that leave the factories.
Manufacturers continue to perform research and development on their existing sprinkler and nozzle products. Not only are they are looking for ways to improve the product, but to reduce manufacturing costs. Sprinkler and nozzles will continue to be improved and reworked to improve uniformity, enhance reliability and to add features at a lower cost. In the future, sprinklers will continue to be developed that use less water while providing added benefits to the end user, be it the contractor or the owner.
Brian Vinchesi, the 2009 EPA WaterSense Irrigation Partner of the Year, is president of Irrigation Consulting, Inc., an irrigation design and consulting firm with offices in Pepperell, Mass., and Huntersville, N.C., that designs irrigation systems throughout the world. He can be reached at firstname.lastname@example.org.