What must be ensured when multiple compressors are installed in parallel on the same refrigeration system?

When multiple compressors are installed in parallel on the same refrigeration system, it is essential to ensure that the oil level is correct in all compressors. This is crucial because oil circulation and lubrication are vital for the proper functioning and longevity of the compressors.

If the oil levels are not maintained correctly, certain compressors may experience inadequate lubrication, leading to increased wear or even failure. Proper oil levels help to ensure that all compressors share the workload evenly and operate efficiently without suffering from oil starvation.

The other options, while important in certain contexts, do not directly address the specific requirements for operating compressors in parallel. For instance, operating at the same speed can help in achieving uniform load distribution, but variations can be managed through proper controls. Each compressor having its own condenser is not typically necessary, as they can often share a condenser. Lastly, using the same refrigerant type is important for compatibility but does not address the critical need for adequate lubrication across devices in parallel operation.