Detecting progress in level measurement systems

Technology being incorporated into driverless cars is also being used to allow production managers to see highly accurate data about the levels of materials stored in huge silos around their sites.

“We’ve introduced radar technology at 80 GHz, which is the same frequency as used by the automotive industry in collision avoidance systems,” says VEGA marketing manager Doug Anderson.

The firm has the VEGAPULS 64 for liquid level detection and the VEGAPULS 69 for solids. The benefit of using 80 GHz is the intense focus of the signal and the small diameter of the antenna system.

These systems are generally mounted inside the roof of a tank to fire signals down to bounce back off a product and calculate how much remains.

“We built 200 devices of 80 GHz radar and put them around the world on the most challenging applications we could line up for them,” says Anderson. “We were really impressed by how they performed.”

You can have digital displays shared on the internet with the product supplier. You can push an email to the supplier when they need to deliver

VEGA marketing manager Doug Anderson

The level measurement technology is designed to withstand incredibly hostile processing environments.

“We have 80 GHz radar working at temperatures of up to 250°C and pressures of 40 bar,” says Anderson. “There are other radars that will deal with 400°C and 400 bar.”

He cites an example of where this is useful. “In power stations there are high-pressure high-temperature steam boilers used for storing energy. They need to be constantly fed water.

“If antenna systems couldn’t stand the pressure and temperatures, you would see ingress of the product and then failure.

“We also measure toxic products – ammonia, chlorine, acids, and so on. Radar will measure in these environments and not be affected by fumes.”

The system works using a four to 20 milliamp loop to convey the information picked up by the radar.

“We measure the tank and we calibrate the system so the milliamp output will be determined by the distance travelled by the signal,” says Anderson.

Dial-up available

This can then be translated into something as simple as a dial on the wall, showing how much of a product is left in a tank, or into a much more sophisticated arrangement.

“You can have digital displays shared on the internet with the product supplier,” says Anderson. “You can push an email to the supplier when they need to deliver.”

This effectively creates automated supply to demand. The VEGA inventory system includes sensors, software, communications and management.

“A company making flour and delivering it to bakeries could have level sensors on the silos and organise their deliveries to replenish the silos,” says Anderson. “The buyer is automatically notifying the seller. The supplier gets longer term contracts and can optimise deliveries.”

Smart technology looks set to play a big role in the level measurement of the near future.

“We have added Bluetooth as a communications device so you can download a VEGA Tools app and use your phone to set it up a radar device as well as seeing its readings,” says Anderson.

“On an iPhone you can see an echo trace with a blip where the level is and check it against the tank to confirm it’s working right.”

The technology removes the need to climb a 20m ladder up the side of a silo or crawl under machinery in a quarry.

“I can punch into my phone or tablet. It is ease, convenience and speed.”

Essex-based Allison Engineering concentrates on measurement of solids, which can be particularly difficult as these don’t often sit flat within a large silo over time.

Commercial director Jeff Harwood says that as well as avoiding running dry of a critical material, manufacturers have to make sure they keep their books balanced.

“At the end of the year, an accountant wants to know how much material is in stock,” he says. “Companies can be £5 million out in an estimation of what one tank holds – they think it’s two-thirds full but it’s a tenth full. This has to be written off in the accounts and the accountant goes crazy.”

Accurate measurement of such materials is harder than it sounds, says Harwood.

“No one wants to look into the tank because it’s 300ft up to the top and pitch black. Weighing material in and out of the silo just becomes inaccurate within a few days. Customers come to us in April.”

Allison uses laser scanning to build up a detailed image of what is in a tank. “We take multiple measurements using a laser device at the top of the silo,” says Harwood. “A full scan will take 3,000 different materials, like a topological scanner used for mountainsides.”

The image does more than just give a measurement. “The accountant wants to know exactly how much is in there and a picture paints a thousand words,” Harwood says.

“It also shows problems – if it’s measuring a sticky powder or biomass pellets they can stick around the site and get a residue that hardens. If that doesn’t get cleaned, then it’s made the silo smaller.”

Direct line

Again, the way the information is delivered to customers is expected to develop as technology continues to improve.

“We send customers and emails with the image and the mass, but the way the customer gets the data will develop using apps on phones. It will get easier to manipulate the data.”

German-headquartered Balluff helps firms in a range of sectors measure levels of foodstuffs, molten metals, water and much more.

Field sales manager Adrian Sorsby says: “In the automotive industry they want to know what is in the tank so they can get it all out, eliminating waste.

“Customers also need to make sure materials are at the right levels if they are mixing products and they need to know tanks are operational to avoid downtime.”

Balluff supplies a range of level detection systems, including ultrasonic sensors that bounce sound waves down from the top of Source: VEGA the tank to the product.

Industry 4.0 is allowing customers to do quicker and faster batch changes because they have confidence in the levels of materials they hold. Fewer manual checks are required

Field sales manager at Balluff, Adrian Sorsby

“These are great as they are colour insensitive,” Sorsby says. “They can take an average of a rippled surface. They are not bothered by dust, they will clean themselves. However, if there are lots of temperature changes or lots of steam, that’s not always ideal for ultrasonic sensors.”

The firm also sells transducers that float on a liquid level. “Ours have a magnet on the float that is read by the electronics at the top of the probe.”

This can usually sit in the tank all the time and can generally work in high temperatures. “It’s very accurate and reliable,” says Sorsby. “It’s robust technology.”

The firm also sells capacitive sensors that stick at the bottom of a tank and bounce signals back from the top of the surface.

“We have a patented smart level technology for our capacitive sensors which we use for sticky materials like jams in food factories, and in breweries. This ignores residues and foaming and recognises the real level of a liquid.”

Technology is allowing more products to be reliably detected, says Sorsby. “Industry 4.0 is allowing customers to do quicker and faster batch changes because they have confidence in the levels of materials they hold. Fewer manual checks are required.

“You are taking human error out and increasing reliability. You can know exactly when to clean the tank rather than guessing.”