It’s easy to use compressed air inefficiently, most of the time systems are cobbled together using supplies on hand. But taking time to use the correct engineered product will not only keep users safe, it will also save money on compressed air generation costs.
There are a tremendous variety of unique and creative ways people in the food industry have overcome their need for compressed air blowoffs used for cleaning, drying, cooling, conveying and overall processing. You may have seen some of them yourself. It is not uncommon to view open copper tubes, pipes with a crushed end, plugs or caps with holes drilled into them, modular flex coolant lines or nozzles designed for liquid application but blowing air. For compressed air use, these can be dangerous and very inefficient. In many instances, companies will go through such a mixed bag of items to make a blow-off device for their application because it may be “inexpensive” to do or a quick fix. But what is very important to recognize is that these potentially unsafe items will waste your compressed air, costing a great deal of money in the long run.
Due to the environment many food applications can be within, such as washdown with sanitizing chemicals, high or low temperatures, or exposure to the food item; material of the components takes center stage in many cases, with little consideration of using compressed air efficiently. Companies manufacturing high efficiency, high performance compressed air products like air nozzles or air knives will certainly have a selection of materials to suit food industry environments.
It may be difficult to perceive that there is much difference between air nozzles, but there are significant differences in air consumption, noise levels, effectiveness and maintaining OSHA safety standards. The best compressed air nozzles focus on these elements – efficiency, safety and effectiveness. There are services from some air nozzle manufacturers which will provide a comparison for anyone concerned about compressed air consumption and these other values. Knowing what you are currently consuming and what improvements could be made to lower that consumption is valuable information when trying to convince higher-ups to make a change. Comparing consumption, force levels and noise can get you well on your way toward improvement because you can then determine real dollar savings and simple ROI. You may also realize increased safety. This kind of information will be difficult for any manager, executive, or HSE personnel to ignore.
Fix Compressed Air Errors
Here is a common compressed air application error. A plant had installed nozzles designed for liquid blowoff onto an application for removing rinse water from plastic bags prior to packaging that bagged food product into a box. The reason they chose these nozzles was that they were already available in the tool crib. And though we all understand the value of a quick fix, they are not the best long-term solution in just about every situation. In this case they had just set themselves up for higher energy costs and noise exposure – long term.
Years later, this plant did eventually realize there may be another simple solution that could reduce air consumption and noise levels, while still being effective. They were motivated by saving money through reduced compressed air consumption, safety for personnel and simplicity of installation which led them to investigate better solutions. Here is what was discovered.
Three brass nozzles designed for spraying liquid being used improperly to blow air on a food packaging line.
This compressed air user had three water nozzles on a manifold that had ¼” NPT male connections. The air pressure was set at 75 PSIG (5.2 bar), and the air pattern was somewhat round. Their annual usage for this quick fix blow-off device was 7000 hours continuous, and their electric rate for their facility was \$0.10/KWh. They did take advantage of a comparison service from a compressed air products manufacturer because the operation was very loud, and they believed that they were wasting compressed air. They were interested to learn what would be recommended and what the payback period might be when looking at performance of an engineered air nozzle.
¼” NPT round pattern air nozzle engineered for use with compressed air.
The recommendation was a 316SS air nozzle with a standard round pattern and a ¼” NPT male connection. The material was well suited for their environment but more potential gains were available. An engineered design that concentrated on delivering compressed air, rather than liquid, can entrain the “free” ambient air into the air stream much better to generate a hard-hitting force and use less compressed air. Also, with this suggestion, there was no need to redesign their blow-off station. No additional space was required, which may be the case for a blower solution, and no need for capital cost permission from management was required. Simply remove the liquid spray nozzles and replace them with the recommended nozzles.
When the water jet nozzles were tested, they used 17.5 SCFM (496 SLPM) at 75 PSIG (5.2 bar). The noise level was measured at 91.2 dBA for a single nozzle. As a comparison, the engineered compressed air nozzle used only 13.3 SCFM (376 SLPM) of compressed air at 75 PSIG (5.2 bar); and, the noise level was reduced to 73 dBA for each nozzle.
Keep Personnel Safe
One of the primary focuses was safety, in this case a very loud blowoff increased their personnel’s noise exposure. High noise levels will cause hearing damage. OSHA generated a standard 29CFR-1910.95a with a chart for Maximum Allowable Noise Exposure. Though each individual liquid nozzle produced 91.2 dBA of noise exposure, the three combined equaled 96 dBA. From the OSHA table above, the usage without hearing protection is less than 4 hours a day. With the engineered air nozzles, the noise level is 78 dBA for all three nozzles; well below the requirement for 8 hours of exposure. It is difficult to put a monetary value on safety, but using PPE should never be the first step as a solution due to improper use and inconsistency of personnel. If a permanent fix can be installed to reduce reliance on PPE, the wise decision is to install a permanent and safer substitution.
OSHA’s Maximum Allowable Noise Exposure (29 CFR-1910.95(a))
Incredibly Fast and Simple ROI
For the annual savings and the payback period, electrical cost is a very good value to use. Additional benefits of less wear and maintenance on your air compressor, due to reducing the demand for compressed air, are also realized.
The compressed air savings is calculated from the comparison; 17.5 SCFM – 13.3 SCFM = 4.2 SCFM saved per nozzle. With three nozzles, the total compressed air savings will be 12.6 SCFM for the blow-off station. An air compressor can produce 5.36 SCFM/kW* of electricity at a cost of \$0.10/KWh. For an annual savings, we have the figures from the information above; 7000 hours/year x 12.6 SCFM x \$0.10/kWh x 1kW/5.36 SCFM = $1,645.52/year. For the payback period in this example the 316SS engineered air nozzle has a catalog price of \$98.00 each, or \$294.00 for three. The customer above did not disclose the cost of the water jet nozzles, but even at a zero value, the payback period will be 65 days!
Not all blow off devices are the same. With the customer above, they were able to reduce their noise levels and compressed air consumption with an inexpensive, easy to install solution with an incredibly fast and simple ROI. If you see unconventional ways you are using compressed air, in your food plant, there can be many hidden pitfalls - especially with cost and safety. Investigating applications with open tubes or pipes, nozzles made for liquid spray, and even many commercial nozzles can result in saving your company thousands of dollars per year.
* The cost of compressed air depends upon system design and varies from plant-to-plant.
About the Author
Jordan Shouse is an Application Engineer at EXAIR Corporation located in Cincinnati Ohio. After graduating with a Bachelor of Engineering in late 2014 he spent several years in the metrology field traveling the world and getting experience with manufacturing process across many industries. For the past three years he has been working with customers directly at EXAIR helping them make their processes more efficient using EXAIR’s line of Intelligent Compressed air Products.
EXAIR is a manufacturer, direct seller, and global distributor of engineered point of use compressed air products. We are located in Cincinnati, Ohio where we were founded in 1983. All product designs focus on the efficient and safe usage of compressed air. Our products are commonly used in cooling, cleaning, static elimination, conveying, and packaging processes. EXAIR offers one of the largest selections of end use compressed air products on the market today including engineered air nozzles, liquid spray nozzles, air knives, vortex tubes, industrial vacuums and static eliminators. If you want more information see us at www.exair.com, or email us at firstname.lastname@example.org for support on our products.
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