I have tested a (cheap) unit which was intended to find leaks in car roofs, windows, etc.
The set consisted of a transmitter, sending out ultrasonic sound, and a receiver, picking up that sound, giving a led signal (just one led, unfortunately) and an audible signal (beeps, not a hiss).
We first tested this unit on a known leak in a vacuum bag (we detected the leak with the proven Accutrak VPE, which gave a clear hiss when pointed at the leak.
The noname unit was NOT able to detect the leak, even when it was almost pushed into it. We changed batteries, we changed earphones with the Accutrak unit, but to no avail. Was this a malfunctioning unit??
We then tested the transmitter that came in the set, using the Accutrak unit to detect it. My friend yelled “turn it off!!” as the hiss in his earphones was incredible.
We then did the same with the noname unit, and indeed it was able to pick up that transmitter. At least it did work, but definately not on the vacuum bag. We held the transmitter under a piece of bag, and that was enough to hide it for the noname receiver.
We then moved to a window, to see what happened there. Where the window was leaking, we were able to detect the transmitter on the other side of the window. So it seemed that the unit was doing the job it was purposed for. Which, unfortunately, was not picking up air leaks in vacuum bags…
We then tested the VPE unit further. (although we are selling it already for over 10 years, we now were curious on how well it performed. My friend is a full time composite and infusion engineer, and handles these things more often than many other people.
When standing in a 30ft boat, in the middle (infusion of inner skin) we turned the Accutrak unit to the front: nothing in the earphones. Then to the back: hiss. So the leak was in the back (we already knew that…). Then slowly approaching the leak, every time probing left and right, we were able to detect the leak quite quickly. (this was a leak in the middle of the bag, by the way)
Also running the Accutrack unit along the tape will detect various small leaks, that are not visible or audible.
Conclusion:
A leak detector is a great unit for getting the most of your infusions. However, care must be taken to select a unit. The cheap noname unit I tested (Korean product) was no good. We informed the manufacturer.
The Accutrak VPE unit was working well.
There also is a more luxury Accutrak VPE-1000 unit, which is frigging expensive (1000 dollars or so). I ordered one to see if it works better than the VPE unit. If not, I can return it.
The best I can do on the VPE unit is some 350 euro.