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Vacuums - How Physics Relates to Happy Customers

Over the years, I have been asked to write a number of articles on various topics regarding vacuums. Generally these topics relate to equipment selection and/or equipment maintenance and troubleshooting.

By David H. VanGorder

04/01/18

Over the years, I have been asked to write a number of articles on various topics regarding vacuums. Generally these topics relate to equipment selection and/or equipment maintenance and troubleshooting. While I am always happy to contribute, I sometimes feel that I am regurgitating some of the same information over and over again, and I often wonder what I can say that hasn’t already been said, and what I can say that will be of interest to the reader.

As a car wash operator (full service, express, or self service) you offer your customers a service that many of them could perform for themselves, at home, if they really wanted to… but they come to you. Why? I would say it is because you have all kinds of equipment they don’t have — it is quick, convenient, and relatively inexpensive, and in the end, you provide a service that is superior to what they can do for themselves. In other words, you provide a service that is of value to your customers.

Regardless of the type of car wash you operate, your customers come to you for two things: to clean the outside of their vehicle, and to clean the inside of their vehicle. To me, each of these is of equal importance. I like my cars to be clean on the outside because they look nice that way, and because I know that keeping my car clean is part of keeping it well maintained. The same thing can be said for the inside of my vehicle, but to me, the interior space is much more personal — that is my space, and I want it to look as “like new” as possible.

SUPERIOR VACUUM

Aside from my routine of always removing any items or debris from my vehicle, it always looks and feels better to me after it has been vacuumed. As a car wash operator, you should provide a vacuum for your customers (or your employees) to use, which is superior to any vacuum the typical customer would have available to them elsewhere. You need a vacuum system that doesn’t just vacuum up the dirt and debris sitting on the surface of the carpet or upholstery — you need to get all of the sand, dust, and debris that is buried in the roots of the carpet and upholstery fibers. If you do this, you will be offering your customers a superior result, and as a result, you will provide more value to their experience.

So how do you ensure that you offer a superior vacuum experience? The answer is to provide high-performance vacuums that have superior airflow (cubic feet per minute — CFM) and suction power (inches of water lift — as measured on a water-column gauge). These are both terms that many people have heard before, but not everyone really understands how these measures relate to the performance of the vacuum.

From the basic laws of physics, we know that in order to move an object, we need to create a force on that object greater than the force holding it in place. To do this when vacuuming dirt, you need to generate enough air speed passing over the surface of the particle so that, when combined with the friction coefficient of the particle, this greater force is generated, thus causing the dirt particle to move. The bigger and heavier the chunks of debris are, the faster the airflow needs to be in order to pick it up and make it move.

Thus, for the particle in the graphic (on page 36) to move in the direction of the AirFlow, the dynamic force (Ff) must be greater than the static force (Fg). This is why AirFlow (air velocity) is responsible for moving dirt and debris into the vacuum intake.

AIRFLOW, SUCTION

The air velocity generated by a vacuum is a derivative of the volumetric airflow (CFM) and the cross-sectional area (square inches) of the vacuum hose or pipe. In order to have higher air velocity you need either a higher airflow from the vacuum or a smaller diameter hose. The standard hose sizes used in the car wash industry are either 1.5” diameter or 2.0” diameter. I personally like the 1.5” hose diameter because it is lighter, more flexible, and easier to use than the 2.0” diameter hose. In order to maintain high levels of airflow against greater resistance, the vacuum needs to generate higher water lift. When you are vacuuming carpet and upholstery, you only need airflow (velocity) to pick up the debris that is sitting on the surface, but if you want to suck up the dirt and debris that is buried deep in the weave, you need to have a vacuum that generates higher suction (water lift). It is the higher water lift that enables the vacuum to maintain enough airflow to move the dirt, despite the heavy resistance to airflow that the carpet and upholstery impose on the vacuum. In short, you could say that the suction power (water lift) of the vacuum dislodges the dirt, and the airflow (CFM) of the vacuum picks it up and pulls it into the vacuum. Again, this is an explanation of the basic laws of physics that come into play when using a vacuum to clean your car.

Vacuum arch with dual-vacuums and hoses.

SYSTEM TYPE

Many people are divided as to what type of vacuum system is the best in today’s world — a central vacuum system with multiple drops, or a number of standalone vacuum units? It is not my intent to argue the merits of one type of system as compared to the other (but to some degree, I will). Each system has some positive and negative attributes that you need to consider when making a choice of equipment; that is another subject for another time, but up-front cost, installation cost, maintenance cost, repair cost, redundancy, performance, appearance, and flexibility are just a few things to consider when making a choice of vacuum equipment.

With all that being said, purely from a “performance” perspective, I am a firm believer that a standalone, dedicated vacuum, with one hose, will provide the best vacuum for your business. I know some people really like the big central vacuums, with multiple drops, and variable speed motors, and I understand their reasoning and arguments. My problem with these systems is that you can never maintain the high suction power (water lift) needed to deep clean the carpet or upholstery when there are multiple hoses in use at the same time.

If, by contrast, you are using a dedicated vacuum that has a single hose, you are getting 100 percent of the airflow and suction power that the vacuum can generate, and that performance will be superior. If you are using a vacuum that has more than one hose, you may be able to ramp up the airflow to accommodate both users, but if one person is trying to suck dirt from deep in their carpet (which requires high water lift), and the other person has their tool in the air at the same time, the vacuum is going to draw air in through the path of least resistance, and it will not create the suction power needed to dislodge the dirt from deep in the carpet. For this reason, I recommend a single-user vacuum setup, as opposed to a central vacuum system — again, from a performance perspective.

Based upon this assessment, for best performance results:

Do…
• Buy a vacuum that generates at least 100 CFM airflow per station.
• Buy a vacuum that generates at least 90 inches H2O suction power at each station.
• Check the performance of your vacuums on a regular basis.
• Have a dedicated vacuum for each hose.
• Keep your filters clean.
• Inspect that all seals are in good condition.
• Inspect that your hose and tools are in good condition.
• Empty your vacuum regularly.

Don’t…
• Buy a consumer grade “shop vac” (these have good airflow, but lousy sealed suction).
• Try to run multiple hose drops off of one central vacuum producer (you will suffer from reduced sealed suction power).
• Locate your vacuum so that a long pipe or hose run is required to get to the work area.
• Neglect your vacuums.

Again, if your goal is to provide superior interior cleaning services for your customers, you need to have equipment that is capable of performing at a superior level. If your customers are like me, and they appreciate a vehicle that is thoroughly clean on the inside as well as the outside, then you owe them the opportunity to do the best job possible with regard to both areas of the car. By doing so, you will increase the perceived value of your wash facility as compared to others, you will build more customer loyalty, and you will be able to demand a premium price for your superior services, resulting in more profits for your business.

Hopefully, this article has provided some information for thought as it applies to your car wash facility and your vacuum systems. If nothing else, maybe you found the basic physics lesson to be an interesting departure from the “same old vacuum article.”

 

 David H. VanGorder is president of Doyle Vacuum Systems LLC. You can visit the company on the web at www.doylevacuum.com.

 

 

 



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