Air is a troublesome contaminant in hydraulic fluid. Once it enters and becomes entrained, it’s a pain to remove. If it goes undetected or unmitigated, it can delay system response, decrease performance, degrade the fluid, and wreak havoc on hydraulic pumps.
“It’s not like the bubbles that rise to the surface in your glass of beer. The air becomes almost atomized, and because the oil is so turbulent, it looks like a milkshake or a latte,” said Jim Oftelie, CEO of Amtech and a seasoned mechanical engineer.
Oftelie found a unique solution to measure and monitor entrained air in hydraulic fluid that gives OEMs real-time data. With the HYDRx Gas Void Fraction Monitoring System developed by Daniel Gysling, CEO of CorVera, Oftelie places transducers along a hydraulic hose and collects data on a laptop. The HYDRx uses proprietary sonar technology to measure the speed of sound within the hose and determine the amount of entrained air in the oil. His hunt for a solution like this began 20 years ago.
“I took a job right out of college as a service engineer,” said Oftelie. “I was a subject matter expert in hydraulic systems and products, and I would be the guy helping people troubleshoot and figure out the correct service parts and write technical bulletins. I’d be on the phone, and with a day’s notice, I’d go to the other side of the country, or anywhere in North America, to help valuable customers with our products.”
Through experience, Oftelie developed a keen understanding of reservoir design and the impacts of aeration.
“I remember thinking, ‘Boy, I wish I knew of a way to measure air in hydraulic systems,’” he said. “It’s the one thing we really don’t know anything about. We can get pressure, temperature, chemistry. We can use particle counters, filter the oil, separate out the water — everything. But air…my friends and I call it ‘the ghost of the machine.’ It comes and goes, and we really don’t know what’s going on.”
After a few job changes, he joined another company as a hydraulics specialist working mainly with machine braking and steering systems. During that time, he discovered the CorVera technology that could measure the amount of air in hydraulic lines in real time using acoustic analysis and software.
“I went crazy. It was just amazing. I couldn’t sleep for two weeks,” said Oftelie. “When I found it, I brought it to my boss, and he said, ‘That sounds pretty good, here’s a budget. Why don’t you buy a couple of these systems and do a feasibility study along with the work you’re doing with our internal customers?’ Because that’s what I’m supposed to do as an engineer — find new and better ways of doing things.”
Oftelie performed a three-year feasibility study at a tech center in Peoria, Illinois, and installed the system on a couple of machines at a proving ground in Tucson, Arizona. After gathering and analyzing a lot of data, he showed aeration was present in the machines’ hydraulic systems and proved that he could quantify and measure it.
Not only is this fascinating, but it also heralds a mindset shift in diagnosing and mitigating aeration. Fluid power professionals often use experience and gut instinct to evaluate problems they can’t see or measure. Now, they’ll have the numbers to prove it and select the right solution.
“I call it the black art of hydraulics,” said Oftelie. “We can understand the functions of air and what it does in your system, and come about it by process of elimination saying, ‘Well, we don’t know what’s going on, but that reservoir is kind of small and your system is overheating.’ There’s a flag in the field right there. Problems associated with high temperature, and oil properties change — it oxidizes, starts smelling funny, and turns black. You got all these symptoms of aerated oil, but what do you do about it?”
Using a larger reservoir or installing a baffle could mitigate the symptoms, but it might not solve the aeration problem. Plus, an OEM may not have room to install larger equipment. Without any data, the OEM may waste effort, decrease machine efficiency, or make decisions that don’t work and add cost.
“I could put a system on their machine, leave it on there for six months, and they could get six months worth of aeration data on a continuous basis. That would be immensely valuable,” said Oftelie. “Once they understand that number, they could compare it to other machines that have the same problem, or whatever. Engineers can take this and run with it in any direction. It’s up to them.”
Oftelie emphasizes that the system gives OEMs data passively and continuously. There’s nothing to break, and there’s no need to worry about running the machine at a certain pressure, altitude, or other environmental condition. None of those types of restrictions apply.
“Based on the acoustical properties of the oil, we can measure how the oil deals with sound. The algorithm will tell us exactly how much air is in the oil,” he said. “Instead of talking about it qualitatively, we move to quantitative.”
Amtech
amtechllc.com
CorVera
corvera.io
Filed Under: Contamination Control, Featured, Fluids, Sealing & Contamination Control Tips, Technologies, Trending