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Eric Wise Tells Gasworld All About Otodata's New Capacitive Probe for Liquid Cylinders

Updated: Oct 26, 2023

Originally published in Gasworld Magazine, September 2023, Page 46 | PDF



Eric Wise, Vice-President of Industrial Solutions at Otodata, tells Gasworld about the Canadian company’s collaboration with Rotarex to launch telemetry for liquid cylinders.


It’s 2023 and we all know how telemetry usage has expanded well beyond large bulk tanks. For years now, the technology has been making strides and moving into everything from restaurant carbon dioxide (CO2) to manifolds, bundle packs to hardgoods. There is now even telemetry to monitor how many bags of ice are in freezers outside of convenience stores.


Yet despite these advances some assets have still proved harder to monitor.

One example is liquid cylinders, sometimes referred to as “dewars” or “liquid cans.” These mobile cryogenic assets have long presented a strong business case for telemetry, but being so mobile made it a challenging proposition.


The first hurdle with these assets is measuring how much gas they are holding. It’s a challenge because most of these cylinders do not have differential pressure ports for measuring the volumes within. Scales can sometimes work, but it can be difficult to place cylinders on them, even with ramps. Mechanical float gauges are occasionally a solution, but many existing float gauges have no telemetry-ready outputs.

The second hurdle is the question of mobility – in other words, accounting for the fact that these assets are on the move. This raises several questions. Should the telemetry equipment live at the customer site? If so, how will it account for different liquid cylinders constantly being delivered and removed? Or should the equipment live on the cylinder itself? If so, is the solution cost-effective enough to be installed on every cylinder in a fleet?


About five years ago, Wise Telemetry – now Otodata – and Rotarex began discussing these types of challenges around telemetry applications. And the pair concluded that by combining Rotarex’s expertise on cryogenic systems with Wise Telemetry’s knowledge of remote communications they would have a viable answer. It took years of careful development, testing, and collaboration for the solution to arrive – the Rotarex C-Stic Lite, with built-in Otodata wireless technology.


Step one: Sense it

What dimensions were there to the challenge? To address the first hurdle, which lay in sensing the amount of liquid in the cylinder, Rotarex looked to its experience with capacitance probes. A capacitance probe is a specially made rod that is inserted into a cylinder or tank. As the liquid level changes, the capacitance of the rod also changes and can be sensed by electronics. This capacitance value is then converted into a value showing the percentage of fullness of the vessel. Rotarex has many decades of experience creating products with capacitance probes such as the original C-Stic. And all that experience went into its most advanced version yet, the C-Stic Lite.


“For years now, the technology has been making strides and moving into everything from restaurant carbon dioxide to manifolds, bundle packs to hardgoods”

The C-Stic Lite is an accurate and reliable technology, but with the lowest total-cost-of-ownership available on the market today for measuring cryogenic levels. It is accurate within a tenth of one percent (±0.1%) and has no moving parts, which gives it superior longevity. It is made of robust stainless steel and works with any of the common gases, such as oxygen, argon, nitrogen, CO2, and helium. Today the probe has become standard equipment for some of the largest manufacturers of liquid cylinders. It will also become the standard in many liquid CO2 cylinders by the end of this year. While gas distributors can connect to these C-Stic Lites that are already in the market by using a wired connection, an integrated solution provides many additional benefits.


Step two: Send it

With the first hurdle taken care of by the C-Stic Lite, Otodata’s technology was then linked up to solve the second hurdle – getting the probe’s readings to the gas distributor. Early on, Otodata and Rotarex realized it was essential to have the communication equipment seamlessly connected into the sensing hardware. This provides several key advantages:

  • Optimized form factor – Rather than having a generic aftermarket telemetry product that plugs into the C-Stic, the companies wanted a solution that would be seamless. This provides the user with a better experience and a product specially built for the task.

  • Easier calibration – The C-Stic Lite can be calibrated to full while in the field, to achieve maximum accuracy. By integrating the communication equipment into the probe, this calibration can be done without the use of additional hardware and can even be done remotely.

  • Lower cost – Integrating the communications equipment directly into the probe lowers the overall cost compared with an aftermarket bolt-on. This is because the housing and electronics are custom made to eliminate any waste and there is no need for extra connectors or wires plugged into an external piece of hardware.

  • Durability and reliability – An integrated design significantly improves the durability and reliability. It was determined that connecting an external piece of hardware to the C-Stic Lite via wire was a potential failure point due to the dynamic and mobile nature of these assets. For example, the wire could become unplugged or severed during transport or use. Additionally, the compact nature of an integrated design makes the final product smaller and less prone to being damaged by bumps or vibration. There is also no need to mount an external piece of hardware on the cylinder itself.

  • Better battery life – For any high-volume telemetry solution, battery life is critical. Integrating the sensing and communication systems directly allows for optimized power consumption. This allows the Otodata communication system to wirelessly emit a reading every 10 seconds for 12 years – without changing the battery. The integrated communications equipment transmits the cylinder’s fill level via Bluetooth. These Bluetooth readings are picked up by one of Otodata’s standard cellular monitors. The monitors are completely battery powered and have a battery life of 15-plus years. Each monitor can receive readings from multiple nearby cylinders. This combination of Bluetooth transmitters and a cellular monitor solved the question about what hardware should live at the customer site and what hardware should always be attached to the cylinder. The probes, with their integrated Bluetooth transmitters, will always remain with a cylinder, while only the Otodata monitor lives at the customer site. This again reduces overall cost, since the Bluetooth transmission hardware is affordable enough to place on every tank, while the cellular communication equipment is limited to just the customer site. It also means the there is no interaction required by the end users, because the monitors automatically pick up the Bluetooth transmissions anytime a cylinder is brought within range.


Step three: Put it all together

How does the system work in the real world? Here’s an example. Say a cancer research lab uses liquid nitrogen for its work, and it typically has three liquid nitrogen cylinders on site at any given time. Simply place the cellular Otodata monitor on a wall near to where the cylinders are stored. Then, make sure that each liquid cylinder is equipped with a C-Stic Lite with integrated Otodata Bluetooth. The cylinders’ fill levels will then all be detected by the same cellular monitor. Whenever empty cylinders are taken away, they will automatically be removed from the customer’s location on the Otodata dashboard. When a new cylinder is brought in, it will automatically be picked up by the cellular monitor and added to this customer’s location on the dashboard. There is no manual interaction required, and the delivery team does not need to do anything special.


“As the market embraces the era of digitization, such strategic partnerships will become increasingly vital”

After many years in the making, this product offering is an example of what can happen when two industry experts come together to jointly solve a problem, and it reflects both companies’ commitment to pushing the boundaries of what is possible. As the market embraces the era of digitization, such strategic partnerships will become increasingly vital. Embracing this spirit of collaboration, the future promises even more transformative advancements, shaping the industrial gas landscape for years to come.

“As the market embraces the era of digitization, such strategic partnerships will become increasingly vital”.

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