Electrostatic Sprayers, are they the new Snake Oil?
Posted by Shimon Petegorsky on
There is no question that purveyors of electrostatic sprayers have done an excellent job in marketing. They have created a buzz in the disinfecting market, and have gotten customers to dish out up to a thousand dollars for a handheld version, to many thousands of dollars for a larger capacity unit.
Initially it was niche companies selling their products to niche customers, and more recently some of the global corporations in the sanitation products industry have entered the fray. What is eerily missing from their product literature (at least from what I have seen, and I have searched thoroughly), is actual evidence or studies showing that electrostatic sprayers offer any benefit relative to a ULV or HVLP fogger.
Instead, they may rely on videos showing a product sprayed with an ES Sprayer that seems to be covered with spray on all sides. Odd thing about videos like that, we have seen some videos of fake ES Sprayers (yes their are many fake ones on the market), that show the same thing.
The fact is, that a good ULV Fogger, or HVLP fogger can provide 3D coverage. Think of a misty or foggy day, anything walking through that mist will be enveloped by it. Foggers work essentially the same way as a mist, but instead of walking through it, they bring the mist to the object via their blower.
Next, some of these companies may try to entice customers by explaining the "science" of Electrostatic Sprayers. After all, everyone is familiar with static electricity. It is a simple concept to understand, electricity can cause objects to attract to each other.
In theory, that sounds nice, but the reality is not that simple. Opposite charges attract. A negative charge will attract to a positive charge. It is natures way of creating equilibrium. Electrostatic Sprayers positively charge the chemicals it disburses. The problem is that most objects, are neutrally charged, and their is no innate attraction from a positively charged object to a neutrally charged object.
There are some objects that do have a slight negative charge, primarily some metals. So on may be inclined to think that an electrostatic sprayer would be ideal if you have a lot of metal objects to disinfect (maybe a gym).
Well, not so fast, because there are drawbacks to an electrostatic sprayers, aside for the price (and the authentic ones we have seen are quite costly). Electrostatic force is a very weak force, so if their is an opposing, stronger force, it would negate the electrostatic pull. So if the sprayer had a powerful motor, the force of the motor would negate the benefit of the electrostatic pull.
As a matter of fact, Boeing has done a study on electrostatic sprayers, and concludes that it's maximum effective range is 4 feet, anything beyond 4 feet, and the force of GRAVITY, would negate the pull of the electrostatic sprayer. For this reason, the reputable ES manufacturers advise customers that it should be used at a distance of 2-4 feet from the object it is disinfecting.
Compare this to our backpack fogger, that has an effective range of 20 feet, or even our handhelds that have a range of 5 feet or more, and you will be able to disinfect a much larger area, in a much shorter period of time with our foggers, than you would with an electrostatic sprayer, all at a fraction of the cost.
There are a couple of studies that some sellers of Electrostatic Sprayers point to to hype their products. Strangely, it seems that they never actually read these studies.
The above study, compares an electrostatic sprayer to a standard agricultural sprayer (an an old one at that). The study found that on some objects, the ES sprayer performed mildly better, yet there were materials where the agricultural sprayer outperformed. The article recommends ES in it's conclusion due to the fact that it wasted less chemicals, and the other sprayer had runoff which sometimes contained bacteria.
Some sellers of ES point to this in promoting the superiority of their product. What they fail to mention, is that this report DID NOT compare electrostatic sprayer to ULV or HVLP foggers. The fact is that those do not have runoff either, and also are more efficient in usage of chemicals. So the advantage they had over conventional sprayers are not applicable to foggers.
Health Ontario summarizes this study on their website (easier read) click on link https://www.publichealthontario.ca/-/media/documents/ncov/ipac/2020/07/faq-covid-19-electrostatic-sprayers.pdf?la=en
Boeing has also done a study on electrostatic sprayers. Yet, they did not compare it to foggers, as they claimed to fear that the small particles of ULV foggers could damage sensitive electronic instruments in the vents of the plain. If was a conspiracy theorist, it would seem almost as if all the studies are intentionally avoiding comparing electrostatic sprayers to ULV or HVLP foggers.
I did find a newer study, based on the specific brand name product, one may think the product was commissioned by a specific company. Yet again, it does not compare the expensive electrostatic sprayer to a ULV Fogger, and does not make the case, or even attempt to, that electrostatic sprayers are superior to foggers.
So after all my research, I have yet to find a study that shows that an ES performs better than a ULV or HVLP fogger. You would think with the deep pockets pushing it, such studies would have been attempted, perhaps the studies did happen, but the results were not what they would have wanted it to be.
In conclusion, perhaps calling electrostatic sprayers "snake oil" is a little harsh. After all, they are still spraying disinfectant, and seem to do a decent job. The question is does it do a better job than a ULV or HVLP fogger, and is it worth making a huge sacrifice in effective range and paying a premium in order to do so. Despite looking extensively, I have seen no evidence of that.
Thank you for your clarification of this type of equipment. As a past owner of a business in the paint/coating industry, i am too familiar with ES methodology, neutrally charged or non-chsrged materials, Faraday effects, etc. I am about to receive the pH strips and test the HCOL generator and fogg our offices for the first time.