What instruments are used to determine the efficiency of the negative air pressure unit?

The determination of the efficiency of a negative air pressure unit is crucial for ensuring proper air quality and contamination control in environments where asbestos or other hazardous materials are handled. The use of a Magnehelic gauge and manometer is specifically appropriate for this purpose because these instruments measure air pressure differentials.

A Magnehelic gauge provides a direct reading of the static pressure in the ventilation system, allowing workers to assess whether the negative air pressure is being maintained as needed to prevent contaminants from escaping the work area. Meanwhile, a manometer can give a more detailed measurement of the pressure difference across filters or other system components, ensuring that airflow characteristics are within acceptable limits.

In contrast, the other instruments mentioned in the options serve different purposes. An amp meter and gauge are more suited for measuring electrical current rather than air pressure. A thermometer and barometer are used for measuring temperature and atmospheric pressure, respectively, which do not directly relate to assessing negative air pressure systems. Lastly, a calorimeter and sound level meter would measure heat and sound levels, which do not provide the necessary data required for evaluating negative air pressure efficiency. Thus, the combination of a Magnehelic gauge and a manometer is critical for effectively monitoring and ensuring the proper function of negative