Answer :
Final answer:
To protect the vacuum pump from excess moisture, a desiccant filter should be used. It absorbs water vapor to prevent damage to the vacuum pump and ensure accurate laboratory conditions are maintained.
Explanation:
To protect the vacuum pump when excess moisture is present in a system to be evacuated, one would use a desiccant filter. This device helps to remove moisture from the system, thereby safeguarding the vacuum pump against the harmful effects of water vapor. This is particularly important in laboratory settings where precise conditions such as low pressures (~10-5 torr) are required to avoid condensation and ice formation, which can lead to inaccurate measurements and potentially damage the equipment.
Desiccant filters are commonly used in various applications to dry the atmosphere surrounding sensitive equipment or samples. They contain materials such as calcium chloride or silica gel, which effectively absorb moisture from the air. When used in conjunction with vacuum pumps, these filters ensure that any moisture aspirated from the system is captured before it can enter and damage the pump.
Other devices mentioned, such as pressure relief valves, flow control valves, and temperature sensors, serve different functions in managing pressure and flow, or monitoring temperature, and do not primarily address the issue of moisture within evacuated systems.