How to Detect Ammonia Leaks in a Refrigeration System

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Things You'll Need

  • Litmus paper

  • Sulfur stick

  • Lighter or match

Many commercial refrigeration systems have alarms that indicate ammonia leaks. If you smell ammonia but don't hear an alarm, you can use either litmus paper or a sulfur stick to detect an ammonia leak. Ammonia can be in gas or liquid form. The liquid form is flammable so only use a burning sulfur stick to detect small leaks of ammonia gas. Ammonia is also hazardous to your health. Wear respiratory equipment to prevent irritation to your nose, eyes, throat and lungs while checking for leaks.


Litmus Paper

Step 1

Dampen a strip of litmus paper, also called indicator paper. Use tap water to dampen it rather than saliva. This product contains phenolphthalein, which should not be ingested.

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Step 2

Walk around the refrigeration system slowly while watching the litmus paper. If you notice the paper turn pink or red, stop walking. This color change indicates an ammonia leak.

Step 3

Dampen another strip of litmus paper after you have sealed the leak. Hold the paper near the area of the leak and wait several minutes. If the paper turns pink or red again, the refrigeration system requires additional repairs.

Sulfur Stick

Step 1

Grasp the end of a sulfur stick opposite the wick.


Step 2

Light the other end of the sulfur stick with a lighter or match.

Step 3

Walk around the refrigeration system slowly and watch the sulfur stick. Pass the stick over and around the area where you suspect the ammonia leak. If the sulfur stick begins to emit white smoke, this indicates the presence of ammonia.


High concentrations of ammonia can cause blindness, chest pain and breathing problems. A high concentration is more than 300 parts per million. Two thousand or more parts per million can cause death after only a few breaths of the gas.


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