How many inlet valves are present in the M17A1 respirator?

The M17A1 respirator is designed for use in contaminated environments where respiratory protection is essential. The presence of two inlet valves in the respirator is critical for its functionality. This dual-valve system allows for easier inhalation and exhalation, helping to maintain a positive pressure inside the mask. The two valves work together to ensure that air enters the mask smoothly and efficiently while allowing exhaled air to be expelled without creating a vacuum that could pull in contaminants.

This design optimizes the safety and comfort of the user, allowing for longer periods of wear with reduced risk of inhalation of harmful substances. Therefore, the correct answer reflects the practical design and engineering considerations in developing the M17A1 respirator to ensure effective protection for the wearer.