What are the permissible unbalances for ISO and API?

The correct choice is based on the acceptable levels of imbalance specified by ISO (International Organization for Standardization) and API (American Petroleum Institute) standards. The permissible unbalances established by these organizations are critical for ensuring the safe and efficient operation of rotating machinery.

ISO defines specific grades for acceptable unbalance levels measured in micrograms per meter (μg/m). For example, ISO G 1.0 indicates that the machinery is allowed a certain unbalance tolerance, which is appropriate for many applications, particularly in industrial environments. Similarly, API G 0.7 represents the unbalance tolerance suitable for equipment in the petroleum and gas industry, which requires stringent operational limits to maintain reliability and performance.

Understanding these limits allows engineers and technicians to ensure that equipment is correctly balanced, thereby minimizing vibrations that can lead to premature wear or failure. Meeting these standards is essential for maintaining operational efficiency and extending the lifespan of machinery.

By selecting the values of ISO G 1.0 and API G 0.7, the answer aligns with the standards recognized by both ISO and API for permissible unbalances in critical rotating machinery applications.