How long should the air meter be inverted and agitated?

In the process of using an air meter, it is crucial to ensure that the sample is adequately agitated to achieve accurate air content measurements. The specified method recommends inverting and agitating the air meter for a minimum of 45 seconds while not exceeding 5 seconds at a time. This approach allows for effective mixing without the risk of oversaturating the sample, which could lead to inaccurate readings.

Adequate agitation during this specified timeframe helps to ensure that the air is evenly distributed throughout the mixture, thus providing a reliable measurement of air content. This careful balance between time and technique is essential for maintaining the precision of the air content test, which is critical for quality control in construction materials.

While other options may suggest various timeframes or methods, they do not adhere to the established guidelines that ensure both effective mixing and minimized air entrapment, which is vital for obtaining accurate results.