by Matt Migliore

Nozzles and the underlying control systems responsible for their operation are, in many applications, the last piece of technology a process fluid encounters prior to delivery. As such, the nozzle and the spray control system are, in many cases, ultimately responsible for the effective and efficient distribution of fluids. Like the field-goal kicker on a football team, the nozzle is often in the position of winning or losing the “game” with one swift kick, or, technically speaking, spray.

However, with recent advances in spray technology, nozzle users need not stand by on the sidelines with fingers crossed like a speechless football coach as the kicker trots onto the field for the game-winning attempt. To the contrary, spray technology has evolved, like most fluid handling systems, to arm users with an abundance of process data to better maintain efficiency and troubleshoot process conditions.

One Size Does Not Fit All
Regardless of the critical role spray technology may play in determining the ultimate success of a given process, there are still some end-users that see a nozzle as a nozzle as a nozzle. Tom Bassett, vice president of engineering & quality for BETE Fog Nozzle (www.bete.com), warns against such perceptions and urges end-users to gain an understanding of the specific performance characteristics of different nozzle designs. He says end-users can benefit from employing the help of a sophisticated nozzle supplier to identify the proper nozzle technology for a given application.

This manifold body can be fitted with up to five nozzle setups and is often used for humidification of large areas. Photo courtesy of BETE Fog Nozzle (www.bete.com).

While there is still some belief that nozzles are commodity items, Bassett says most end-users today have a healthy respect for the important role nozzles and spray control systems play in fluid delivery applications. “The end-users are now looking at the processes more completely,” says Bassett. “They are looking back into the system for details that they haven’t considered previously, which is helping the [nozzle] providers specify the most efficient solutions.”

Bill Kohley, vice president of the Industrial Division of Spraying System Co. (www.spray.com), also sees an increase in end-user understanding of the value of spray technology. “A nozzle might have once looked like a component piece years ago,” says Kohley. “But now spray systems are seen more as sub-systems within a larger production line.”

With an Eye on Efficiency
For many end-users, high-performance spray technology can provide a tremendous upside potential in terms of process efficiency. Or, if improperly specified and/or maintained, spray technology can, quite literally, open up a drain on the process.

Bassett says the more detailed information the end-user can provide about the overall application and the process conditions, the more engineering perspective the nozzle supplier will be able to bring to the specification process to help develop an optimized spraying solution. For example, Bassett says he recently worked with an end-user to lower the standard operating pressure of a spray application. The nozzle being used offered a wide operating pressure range of 10 PSI to 300 PSI. And after some experimentation, Bassett says the end-user found the nozzle to provide sufficient spray dispersion and drop size at lower and lower pressures. However, he says, without examining the application with a critical eye, the end-user may never have realized this opportunity for improved efficiency and cost saving.

Pulse width modulated (PWM) spray technology (pictured here) involves switching an electrically-actuated spray nozzle on and off very quickly in order to control the flowrate of the nozzle. This cycling takes place so quickly that the flow often appears to be constant and the coverage remains reasonably uniform. Photo courtesy of Spraying Systems Co. (www.spray.com).

Kohley cites the emergence of pulse width modulation (PWM) technology as a key advance in the area of spray efficiency. Using PWM, an automatic spray nozzle is turned on and off at such high speeds that it appears as if the spray is continuous and it provides adequate coverage. Further, PWM reduces the amount of chemistry sprayed by up to 30 percent and provides the ability to instantaneously change flowrate. While Kohley acknowledges that PWM-based technology is not new to the industrial market, he says the development of faster automatic nozzles and advanced control software are good examples of how spray technology has become more efficient over the years.

In a broader sense, Kohley says the drive toward sustainability and environmental stewardship in industry means more companies are aggressively looking for conservation opportunities. And while increased regulatory efforts and the desire to cut costs are the primary drivers in the pursuit for more efficient spray, Kohley says companies are also more closely monitoring consumption because they think it’s the right thing to do. “It’s one thing to analyze spray because it’s being monitored [by regulators],” says Kohley, “But in the world today, we all strive to use our resources more efficiently and do things that are good for the environment.”

Spray Technology Specification Best Practices
One of the key considerations for an end-user specifying a nozzle for a spray application is the material of construction. Improper material selection can result in increased maintenance costs, process contamination, and a reduction in the lifetime of the nozzle, among other undesirable effects. And with recent advances in high-end alloys and alloy blends, there are materials available today to suit just about any process fluid scenario.

To ensure proper material selection, Bassett recommends end-users start by evaluating the specific characteristics of the fluid being handled, as well as the conditions of the process in general, such as operating temperature and pressure. Also, he says, it’s always a good idea to look at other elements of the fluid delivery system, such as the vessel and the piping, to see how the materials are performing there. Finally, he says the user should consider whether the fluid being handled is corrosive and/or erosive in nature. These details, as well as any other application information the end-user can provide, will allow the supplier to identify the most appropriate material of construction, says Bassett.

Kohley says proper technology specification relies on open and honest communication between the end-user and the supplier. He says spray technology has evolved to a point where systems can support even the most complex fluid delivery applications. Whether the most appropriate system will be employed is dependent, however, on how effectively the end-user can communicate the characteristics of the application and the desired end goal.

“If all you need is an accurate and repeatable flow, then that’s what we’ll give you; you may not need a feedback loop,” says Kohley. Nevertheless, Kohley says most modern-day applications require some level process feedback. “It’s just too expensive to mis-spray,” he says. “Even water – our water bills aren’t what they were 20 years ago.”

Bassett says end-users should not only clearly define their application requirements when specifying technology, but also prioritize them by level of importance. This will ensure that the key application requirements are met first and are not overlooked in favor of a solution that may touch on a lot of application requirements but misses the most important one.

When evaluating suppliers, Bassett says end-users should look for an organization that controls all elements of the manufacturing process, from engineering to machining to delivery and support. He says it’s also important to look for a supplier with the capability to run spray tests in a lab to evaluate various operating conditions and verify application requirements prior to deploying the technology in a live environment.

The Future
According to Bassett, the future of spray technology is in the area of customized solutions. He says that as the nozzle designs and materials continue to evolve, more customers are going to demand solutions that are customized to meet the needs of a specific process. Moreover, he says, the leading suppliers in the spray market are becoming more and more sophisticated in their manufacturing processes so they will have the capability to effectively deliver customized solutions.

Kohley sees spray technology evolving along the line of digital technology, with systems getting smaller, smarter and faster. He says, with modern-day computer modelling, suppliers will be able to push the physical boundaries of nozzle form factors and the capabilities offered by smaller spraying systems.

Ultimately, Kohley says he sees more intelligence being built directly into the nozzle, such as thermal sensors, acoustic sensors, and vibration sensors. Further, he says the nozzles of the future will have inherent diagnostic capability to enable real-time monitoring self-adjustments. He says he sees diagnostic information being transmitted to a handheld device, which would allow the operator to have some level of control over the spray technology via remote. “When an end-user is going to put a new piece of spray technology into their plant, they need to look at how they are going to measure and control that technology,” he says.

Matt Migliore is the editor of Flow Control magazine. He can be reached at matt@grandviewmedia.com or 610.828.1711.