Systems and apparatus for controlling fluid flow

A system for processing articles comprising:

• a fluid supply;
• an apparatus for controlling flow fluidly coupled to the fluid supply, the apparatus for controlling flow comprising:
• a body comprising a flow path extending from an inlet to an outlet;
• a valve operably coupled to the flow path between the inlet and the outlet, the valve configured to alter fluid flow within the flow path, the valve comprising a seat and a closure member;
• a flow restrictor having a flow impedance located within the flow path, the flow restrictor comprising:
• a restriction path extending from a first end to a second end along a longitudinal axis;
• a circumferential groove;
• and
• a longitudinal groove extending from the circumferential groove to the first end;
• and
• a pressure sensor configured to measure pressure within a volume between the seat of the valve and the flow restrictor;
• and
• a processing chamber fluidly coupled to the outlet of the apparatus for controlling flow, the processing chamber configured to process semiconductor devices.