The demand for pressurised production

VEGA Managing Director John Leadbetter talks to Roads and Infrastructure about the need for accurate hydrostatic level measurement and the infrastructure pipeline.

With the Coalition’s recent re-election shoring up the Federal Government’s $100 billion infrastructure plan, the sector’s pipeline is set to grow exponentially.

The result, according to VEGA Managing Director John Leadbetter, will be a nation-wide surge in demand for asphalt and subsequently bitumen emulsion.

Bitumen is the central ingredient in asphalt fabrication as it binds stone aggregates to form the finished road product. The nature of the emulsion process, however, creates a potentially explosive environment due to extreme temperatures and an ensuing rise in hydrostatic pressure.

During the emulsion process, water vapour from the bitumen mixture attempts to exit the emulsion tank, causing pressure to increase.

From crusher monitoring to controlling the filling of silos, radar and pressure sensors are therefore a crucial component of multiple applications and areas of asphalt production.

According to Mr. Leadbetter, hydrostatic pressure is exerted by fluid material when gas shifts in a contained space. In layman’s terms, pressure is generated by an agitated liquid, such as bitumen during the emulsion process.   

“New road construction contracts are being awarded almost constantly, and that is only set to increase when the government starts to roll out the 10-year infrastructure plan,” Mr. Leadbetter says.

“I expect to see a sharp uptick in the need for pressure measurement transmitters over the next few years,” Mr. Leadbetter says.   

According to Mr. Leadbetter, pressure transmitters can be used to measure process and differential pressure, level, volume, density and mass flow in all areas of process technology. He says this makes the units well suited to monitoring hydrostatic pressure and therefore ensuring material supply plant safety.

“VEGA’s pressure transmitter range VEGABAR simplifies the asphalt production process by measuring the pressure and levels of liquids, gases and vapours — giving material supply companies peace of mind and safety assurance,” Mr. Leadbetter says.

Mr. Leadbetter says VEGABAR sensors have the ability to measure the temperature of the material medium, while simultaneously enabling precise adaptation to the process through a selection of appropriate measuring cells.

Additionally, Mr. Leadbetter says VEGABAR sensors are not affected by foam generation or variable vessel internals.

“Being unaltered by foam is a helpful feature given the rise in foamed bitumen technology,” Mr. Leadbetter says.

“Foamed bitumen is a mixture of air, water and bitumen. When the mix is injected with a small amount of cold water, the hot bitumen expands to roughly 10 to 15 times its original volume. It’s quite an innovative process.”

According to Mr. Leadbetter, the measuring range of VEGABAR sensors starts at a few mbar and extend to extreme pressures up to 1000 bar.

“The VEGABAR range is designed for use with chemically aggressive liquids in hazardous areas and is ideal for detecting relative or absolute pressure in applications with condensation or rapid temperature changes,” Mr. Leadbetter says.

“The measuring cell of the VEGABAR will detect even the slightest change in hydrostatic pressure, which increases and decreases depending on the material levels.

Mr. Leadbetter says VEGABAR’s measuring principal is a comparative reading, with the pressure of the measured medium acting against the pressure measuring cell.

“The acting pressure is converted into an electrical signal, which is translated into an output signal by the integrated electronics,” Mr. Leadbetter says.

“There are a range of measuring cell technologies employed, including ceramic-capacitive CERTEC and MINI-CERTEC, metallic METEC and piezoelectric and strain gauge cells.”

According to Mr. Leadbetter, this facilitates adjustments to service any individual application need.

“The submersible VEGABAR can be freely suspended above the emulsion tank, and the compact units can be installed directly onto the vessel,” Mr. Leadbetter says.

“Our variety of process fittings and seals also enable secure application.”

Mr. Leadbetter says the VEGABAR range’s metallic measuring cells allow the instrument to deliver proficient measurement accuracy, even under intense conditions.

“The VEGABAR range also offers an integrated self-monitoring function, delivering safety outcomes for the user,” Mr. Leadbetter says.

“The range is characterised by high overload resistance, long-term stability and thermal shock compensation.”

Mr. Leadbetter highlights the VEGABAR 83 as a pertinent example of the VEGABAR range.

“The VEGABAR 83 sensor is completely welded with a metallic measuring cell, making it suited for universal application and process simplification,” Mr. Leadbetter says.

Mr. Leadbetter says when measuring ranges up to 40 bar, a piezoresistive sensor element with internal transmission liquid is used.

According to Mr. Leadbetter, from 100 bar upwards, the VEGABAR 83 uses a strain gauge sensor element on the rear of the stainless-steel diaphragm, with the dry system operating without additional isolating liquid.

Mr. Leadbetter says as with all VEGA products the instrument has full wireless capabilities via the optional display and adjustment PLICSCOM module.

“Given the high temperature and instability of bitumen emulsion and asphalt production, VEGA takes the responsibility of safety very seriously — this is why all of our products conform to the Safety Integrity Level.”

Mr. Leadbetter says he is excited to watch as the industry transitions and evolves around the government’s 10-year infrastructure plan.

“It’s an exciting time to be working in this sector, and it’s great for the growth of the company,” Mr. Leadbetter says.

“Interestingly enough, different states have different wants and needs when it comes to bitumen production and pressure measurements,” Mr. Leadbetter says.

“In Western Australia for example, Fulton Hogan consistently uses a radar sensor, whereas Boral and Downer, who work predominantly in New South Wales and Victoria, prefer to work with pressure sensors.”

Mr. Leadbetter says while the difference is generally informed by the technology preferences of individuals, the distinction is nonetheless interesting.

“We can provide customers with either style sensor of technology, all they have to do is tell us their application needs are we’re good to go.”

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