At what concentration can propane be detected for odour detection purposes?

Propane is added with an odorant, typically ethyl mercaptan, to assist in detection in case of a leak. The lower explosive limit (LEL) for propane is around 2.1% by volume in air. To ensure safety and provide an effective warning for any potential leaks, the odorant is detectable at a concentration that is significantly lower than the LEL.

When considering odour detection, the detection threshold is established as a percentage of the LEL. Detecting propane's odour is effective at approximately 20% of its LEL, which is generally adequate for individuals to sense the presence of propane long before it reaches hazardous levels of concentration. This concentration allows for timely leak detection and subsequent corrective action to mitigate risks associated with propane leaks.

In contrast, the other concentrations listed, such as 10%, 15%, and 25% of the LEL, either do not provide a sufficiently sensitive threshold for odour detection or exceed the commonly accepted safety standards used for effective leak identification. Therefore, detecting propane at 20% of the LEL represents a balanced approach, ensuring safety and awareness among users and personnel.