Review on 🔍 Aprvtio ALD-100 Refrigerant Leak Detector: Effective Freon Leak Detector with Halogen Gas Tester for HVAC AC Systems - R22 R410A R134A - 7 Adjustable Sensitivity Levels - Max Sensitivity of 0.11oz/yr by Enoch Sahay

I tried it on my tank with the R22 pumped out and it all worked (see video). So I'm sure this sensor will react to a leak. The downside is that it also reacts to a number of things - if you breathe it in or touch it, it also reacts to the insulating foam around the suction line if it's close enough. In general it will work, but be prepared for false positives. It comes with a nice cloth case and a couple of spare attachments, as well as cheap batteries (custom sized so it's good they put a few in, you'll replace them later). Some people will complain about the battery compartment and how difficult it is to remove the batteries - I'm not one of them. I went to kindergarten and I know how to wipe my own ass - so I'll find out with this battery case. In general, it's nothing fancy, but it will get the job done if you know how to use it and filter out false positives.