Level measurement at screed factory

Quartzline in Dordrecht got contactless radar level meters

Good insight into stocks of raw materials ensures that new raw materials can be ordered at exactly the right time. VEGA supplied non-contact radar level meters for fifteen silos at cast flooring manufacturer Quartzline in Dordrecht. In the high, narrow silos, which are filled with sand in various fractions, the measuring equipment displays the exact level in real time.

Quartzline is a Dordrecht-based family business that specializes in plastic (poured) floors. The company began in 1976 in Zwijndrecht in a garage box and within a few decades grew into a world player. Whereas in the early years the company also laid floors itself, it has now specialized in the manufacture of the components that make up the floors.

Professional

Fred van Zanten is Operations Manager at Quartzline, and he explains: "We make the components here that the professional uses to lay the floors at their customers. We don't supply the private market directly." He picks up a sample: "Look, this is a sand-gravel floor. It consists of gravel granules that we have dried here and selected very specifically to size. We can make a floor like this in any color the customer wants. The coloring of those grains is also done here in-house." Van Zanten shows another sample: "This is a floor that consists basically of sand. Again, that sand is selected by size, dried and colored. Our floors always consist of an A and B part. The A part contains the sand or gravel. The B part contains the substances that cause the floor to liquefy, flow nicely and then harden."

Concrete ciré

At Quartzline, roughly seven different types of flooring are manufactured. However, because of the variation in grain size and color, the total number of possibilities is virtually endless. "In the Netherlands, you see our floors in both private homes and companies," Van Zanten says. "At Van Mossel Mercedes, for example, the entire showroom and workshop are fitted with our floors. But in theory a private individual can also, through a specialist, have a toilet floor of one square meter fitted with our floor." Although cast floors have always been used, recently there has been an increased interest in sand-cement floors in the private market. "For example, the well-known Beton ciré, which you see appearing more and more in living rooms. And the great thing is, you can also apply it to the walls. So in a bathroom, you no longer need any tile. In addition, it also works very well with underfloor heating."

All directions 

About three years ago, the company moved into its new premises in Dordrecht. In the process, owner Arthur Kaptein's desire to be able to dry sand and gravel himself from now on largely determined the design of the new building. As a result, the factory in Dordrecht has become a rather unique object. "You won't find a second one of these in the world," Van Zanten knows. "It's quite a complex plant, with which you can go in all directions: we can dry sand, sift sand, sift gravel, make all mixes in hundreds of colors, we can recover product that has been colored via mobile weighing cups, and so on. So when I say you can go in any direction with it, I mean that quite literally."

Extremely clean

In addition, the working method is very similar to the food & beverage sector. Even though Quartzline's finished product is not eaten - perhaps it is eaten from time to time - the process must be extremely clean down to the finest capillaries. "I'll tell you why," Van Zanten begins. "Suppose you want a jet-black floor in your office. No problem, we'll make that. Then next comes a customer who has ordered a red floor. Just one black grain has to get stuck in the system somewhere, and we're screwed. You can't say to the customer: just put a rug over that. No, it just has to be right."

In practice, a red floor will not be produced at Quartzline anytime soon after a black floor. "We try to have those colors follow each other a little bit smartly, but still, it should be possible in principle. In practice, that means that we meticulously clean the mixers used after a batch with a giant vacuum cleaner to prevent a grain from jumping along somewhere to the next batch."

110-ton silos

At Quartzline, large quantities of raw materials are kept in stock. Good insight into that stock is crucial. Van Zanten: "You don't want to run out of raw materials. But you also don't want to run out of half a truck, or worse still, order a full truck and then find that it can take half of it back with it. That costs an enormous amount of money." Quartzline's new plant has a pair of impressive 110-ton silos. Sand is sieved into eight different fractions after drying and then stored in silos. To determine the levels in the silos, Quartzline chose a non-contact radar level meter from VEGA, the VEGAPULS 69. This determines the level in the silos very precisely. Including the two cooling towers, Quartzline has a total of fifteen silos that are equipped with a level measurement.

Bobbin and cable 

The choice of VEGA, regarding the level measurement in the silos, was suggested by the contractor who carried out the new construction at Quartzline. Van Zanten: "He was able to tell us that VEGA makes quality products and that radar level measurement is a reliable and robust method for this application." At Quartzline, they don't take things lightly. Before the order was given to equip all large silos in the new plant with radar level measurement, a silo in the old plant was equipped with this measurement technology as a pilot. Van Zanten: "We were like: let's see that it works. And it turned out to be excellent. So after that, we could put out the order with peace of mind." In addition, Quartzline's tank farm, where the liquids are stored for the floors, is equipped with full notification systems from VEGA. An empty detector from VEGA was installed on the ST plant, from which liquid products are sent to the mixer under vacuum. In addition to the radar level meter, the silos are also equipped with a VEGAWAVE S61 full detector.

While there are alternatives to radar level measurement, they are less attractive. Rob Smulders of VEGA explains what is possible: "Sometimes mechanical methods are used in which a bobbin descends via a cable and thus indicates the level. In sand, which is quite abrasive, I would not recommend that. Non-contact radar level measurement is by far the best method." In the old plant, the levels in the silos were determined completely differently. Van Zanten: "We used a very long aluminum stick and a hammer to determine how much was left in the silos. That was fine in itself, but with the kind of silos and numbers we have here, that's not a good idea. It's not for nothing that radar level measurement is chosen in almost all concrete plants."

Aerators

The VEGAPULS 69 is a non-contact radar level gauge that can very precisely determine the level in a silo under difficult - and dusty - conditions. Still, the specific conditions at Quartzline created several challenges. Van Zanten: "With some products, we had to deal with bridge and crater formation in the silos. Sometimes a fairly large rim of sand would remain stuck against the silo. The meter detected that as the top of the raw material in that silo, until that bridge plopped down and the level meter suddenly detected twenty tons less raw material. We solved that with aerators in the silos, so the chances of bridge and crater formation became a lot less."

Some silos are also equipped with a multiple spout. Whereas with a single outlet, there is usually a fairly homogeneous outflow of raw materials into the outlet, with a double outlet, slope formation is more likely to occur. Van Zanten: "We also solved that challenge. VEGA has developed the Yellow Box for such situations, which allows you to measure and analyze numerous variables in the application very easily." Smulders: "The Yellow Box is actually a computer with a modem in it. Look, you can install your measuring equipment at a customer's site and then watch the trends remotely, but much nicer is to be able to read the values from the radar itself directly. When there is a sudden drop in the level, due to slope formation, you can use the Yellow Box to see exactly what the radar detected at that moment. If you then know where the sudden drop in level comes from, you can then solve it."

Play area

The level measurement required a substantial investment, but Van Zanten says it was a good decision. "You also earn back the level meters. Because we now have very precise insight into our stocks, we can buy more competitively. If prices are high at a certain time and we have the room to wait a little longer, we buy in at lower prices a few days later. We can fit three trucks in one silo, so that gives a lot of leeway."  

VEGAPULS 6X

VEGA recently released a new radar level meter that makes level measurement even simpler. The VEGAPULS 6X is a level gauge that can be used for all applications. Where previously a sensor was selected on specific process properties, such as medium, temperature and process connections, this is no longer necessary with the 6X. In addition, the VEGAPULS 6X has become even more intuitive. Commissioning is just a matter of a few mouse clicks. In many cases, customer-specific settings can already be entered into the instrument at the factory. Then it is just a matter of mounting and connecting.