Seven slotted screens

“Dad, what do you need slotted screens for?” my six-year-old son asked me one morning at the breakfast table. I looked at him in surprise and did not have an answer. I could neither figure out what exactly a slotted screen was, nor where my son had picked up the words. Fortunately, at that very moment my wife came into the kitchen and urged my son to get ready for school. So I had a few hours to investigate the matter. A short internet research and a few phone calls later I had someone on the phone who could help me, Mr Paul, the sales manager for slotted screens at HEIN, LEHMANN.

“Slotted screens are components in mechanical engineering that initially do not do anything different from that of any other screen, namely, they separate one material from another. Slotted screens are used in a wide variety of designs in different branches of industry,” explains Mr Paul.

Of salt shakers and cars

“I have an idea,” continued the expert from HEIN, LEHMANN. “Just tell me about your day yesterday and I can assure you that you also will have been indirectly involved with slotted screens that day, as with every day.”

“I’m curious," I replied. “Okay, let’s go. Yesterday, as every morning, I had breakfast with my family first.”

“Did you have an egg for breakfast with salt?” – coming back to the direct question.

I answered yes.

“Here we have first our example. Salt is mined, spun in a centrifuge and dried. This centrifuge has slotted screens that keep the salt in but let the water out.”

“This is exciting,” I replied. “The next thing I knew, I was driving my car to work,” I added.

“Example number two”, Mr Paul added. “Your car is largely made of sheet metal. Sheet metal processing always produces chips. These chips are removed from the abrasives through a slotted screen.”

“Oh really!” I replied happily. “So we have an example from the food industry and one from the automotive industry. I’m curious to see what's next!”

Coffee and rainy weather

“Well, go ahead and tell me more,” he urged. “Once I arrived at the office, I made myself a strong cup of coffee,” I continued, by which time Mr Paul had the third example on his hands.

“Just as a coffee filter is used in your coffee machine, there are also large filters in the coffee industry. This is a variant of slotted screens.”

“Slotted screens are everywhere!” I exclaimed. I pondered for a moment about how my day went on yesterday. “Nothing much really happened after that. I was working and couldn’t go outside because it suddenly started bucketing down with rain.”

“Think about the rain! The water carries away sludge and dirt and flows through a canal into the sewage plant. And what happens there?” the sales manager asked me.

“Well, I suppose they clean it there,” I replied.

“Exactly – with the help of large sludge presses. Here, too, there are slotted screens, in the form of large slotted screen cylinders, which separate the water from the dirt.”

Dextrose, biogas and after-work beer

“You are right. I see nobody can get past slotted screens!”

“Exactly. Go on, tell me more. Maybe we’ll find some examples to tell your son later.”

“I'd love to,” I said. “It was raining cats and dogs, as I said. I had little desire to go out into this storm for my lunch, so I searched my desk for something to eat. I found something in a drawer: dextrose.”

“In fact, the food industry is a big user of slotted screens,” said Mr Paul. “If there were no slotted screens, your dextrose would not exist either. Slotted screens are also used to produce this. This time in the form of so-called arched sieves.”

“There must be a whole split-screen universe!” I joked and Mr Paul agreed with me.

Then he asked me how to heat my home. “We heat it with biogas,” I replied, not without pride.

“You see, the reason I ask is because our slotted screens are also used here. Biogas plants provide clean energy. Without going into too much detail, our slotted screen cylinders are inserted into screw presses that separate the press water (from which methane is later extracted) from the organic solids before the composting process starts.”

I had to laugh, “I think I'll omit this last example. Otherwise, my son will ask me how exactly biogas plants work. I would like to wait a few more years before I explain it.”

I thanked Mr Paul for his explanations and the time he had spent helping me in my quest for answers. “My beer at the end of the day,” I said in farewell, “I’ll drink to you today!”

“Then drink to slotted screens, because ...” the sales manager added. I interrupted him. “Don't tell me the brewery uses slotted screens as well.”

“Exactly,” replied Mr Paul. “As you said, there's no getting past slotted screens.”

With a smile on my face, I hung up and looked forward to the end of the day. Anyway, I now had answers to my son’s question at the ready.

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