The drum industry has a problem: every drum must be tested for leaks, but the standard method with helium is expensive, energy-intensive and unsustainable. Merco Machines from Merelbeke-Melle therefore developed the Hybrid Leak Tester, a hybrid solution that is turning the market on its head. The machine, packed with innovative Siemens technology, allows accurate testing without wasting precious helium. Donaat Wambacq, co-CEO: “If helium testers disappear from the industry within 10 years, Merco Machines will have taken care of that. For an environmentally conscious machine builder, that can count as a motivator.”
From soap bubbles to helium and back
Detecting leaks in drums is surprisingly difficult. “The simplest way is to take a bottle of soapy water and smear it over the weld,” Donaat explains. “If you see air bubbles, you have a leak. That is still the most accurate solution that exists.” But that method is labour-intensive and unaffordable.
Therefore, alternatives were sought. The first attempt was to measure pressure differences in a vacuum. This looked at whether the pressure difference was due to temperature or leakage. But that distinction is sometimes hard to make.
The next step was the helium tester: inject a small amount of helium into each drum, place the drum in a vacuum and use a spectrometer to measure whether helium escaped. “That works super accurately,” says Donaat. “Almost as good as a soap tester. You don’t need any staff and you can fully automate it.”
But there was a catch. “The spectrometer alone is very pricey and helium is also very expensive. This is because the amount of helium on earth is finite. Moreover, helium testers are a hundred to a thousand times too accurate for the drum industry. Everything leaks a bit anyway. For most applications, that level of accuracy is actually not necessary.”
The breakthrough: vacuum testing at constant flow rate
Merco Machines therefore looked for a third way: more accurate than old differential pressure meters, but without the helium consumption of spectrometer testers. After years of calculation and testing, they found the answer in vacuum technology.
“We basically do the same thing as a helium tester, but we don’t count particles. We just look at the pressure,” Donaat explained. At a pressure difference of about 0,6 bar, air escaping through a leak reaches a constant velocity. “At that point, you can immediately tell if there is a leak. You shouldn’t wait anymore.”
That is what sets it apart from conventional differential pressure testers, where you must first pump, then wait, and only afterward measure the pressure drop. That will take you 20 to 30 seconds per drum. Moreover, you then only measure a transition phenomenon, which can be influenced by temperature or air pressure. In the vacuum test, there is a direct relationship between pressure and flow rate. “We can measure immediately.”
The technology operates with 100 millibars absolute vacuum. “That is already quite deep, but it is less extreme than required for helium testing.” The advantage: smaller pumps, less energy consumption and easier sealing.
About Merco Machines
Merco Machines is a world leader in mechanical engineering for the drum industry. The Merelbeke-Melle-based company has 50 employees and achieves annual sales of over 15 million euros.
