The invention concerns a method for flushing of debris from a valve assembly arranged in a fluid line. The valve assembly comprises at least two flow regulating units arranged in series between an inlet and an outlet of the valve assembly. The inlet pressure is larger than the outlet pressure, and each flow regulating unit has a spring element and an opening is provided for each flow regulating unit which initially is set as a minimum opening allowing fluid to pass from one side of the each of the flow regulation unit to the other side of the flow regulation unit. The spring element regulates the opening in response to the pressure difference over the flow regulating unit. The method comprises the following steps in the case when at least one of the openings clogs: —equalizing the pressure over the other flow regulating unit(s) downstream and upstream to the clogged opening thereby—providing a pressure difference across the flow regulating unit where clogging occurs, which pressure difference exceeds the spring force and increases the opening for this flow regulating unit for flushing the debris. The invention also concerns a valve assembly, a use of the valve assembly and a fluid injection valve assembly.