This 1 m2 cloth (40x40") ammonia (NH3) gas based leak detection only $99.00; 4 times the material as the 20x20 (0.25m2) version at half the price. The reaction is reversible so that the same section of cloth can be reused at least 5 times. Can be cut as needed in squares or strips. Cloth is infused with bromothymol blue indicator and changes color in the presence of trace amounts of ammonia (NH3).
If you are looking to test for leaking ammonia refrigerant gas, click on phenolphthalein ammonia gas indicator test papers. Or, if you need a semiquantitative measurement for use in bioreactors or waste management, click on 0-100ppm ammonia test strips.