Phenolphthalein test paperstrips are inexpensive ammonia gas leak indicators for use with refrigeration units or air conditioners. Ammonia changes phenolphthalein paper from white to pink at pH11.6. Only $1.95 for 100 strips.
One end of the test paper needs to be dipped in water first so the ammonia will dissolve onto the paper strip.
Check the Tabs below for more information.