Capillary tubes are tiny but useful pieces of equipment in so much of engineering application, especially in air conditioning and refrigeration systems. Though seemingly so just plain—basically thin-walled, low-diameter tubes—their function is essential to pressure control and enabling effective heat transfer. What you will discover here in this tutorial is all about capillary tubes: purpose, design, application in thermodynamics by the Capillary Tube Supplier, and where they are applied.