How is oil added to the refrigeration system while the compressor is operating?

The correct method of adding oil to a refrigeration system while the compressor is operating is through charging it into the crankcase with a suitable pump. This practice ensures that the oil is introduced in a controlled manner, which is crucial for maintaining the proper lubrication of the compressor components while preventing any damage that might occur if oil were improperly introduced.

When the compressor is running, it is essential to add oil in a way that doesn't disrupt the system's overall operation. By using a pump to charge the oil directly into the crankcase, you are ensuring that the oil is delivered effectively and at the right point in the system. This method provides a way to maintain pressure and prevents air from entering the system, which can lead to efficiency losses or even system failure.

Using other methods, such as pouring oil directly into the compressor or utilizing a vacuum pump, might not allow for precise control or could lead to improper oil distribution, which could harm compressor function. Injecting oil through a service valve might not be a method commonly used in practice, as it may not effectively ensure the oil reaches its intended location within the system.