Which of the following is NOT a method of hydraulic cleaning and filtering?

• A. Flushing
• B. Purging
• C. Purifying
• D. Filtration

Answer: (D)

Hydraulic cleaning and filtering rely on deliberate actions to remove contaminants and air from a circuit so the system can operate cleanly. Flushing is pushing clean fluid through a circuit to dislodge and carry away contaminants. Purging involves removing air or trapped vapor from the system so fluids can circulate properly. Purifying refers to removing contaminants or moisture from the fluid itself as part of restoring cleanliness. Filtration, however, is the ongoing process by which the fluid passes through a filter element to trap particles; it’s a filtering mechanism built into the system rather than a cleaning procedure you perform to cleanse the circuit. So in the context of methods you personally execute to clean and restore hydraulic cleanliness, filtration is the filtering mechanism rather than a cleaning action, which is why it’s the option that doesn’t fit as a cleaning method.