CHAPTER No. 5Adjustments and Maintenance5.1 Capillary Tube5.2 Priming5.3 Pressure Gauge Fitting5.4 Safety Valve5.5 Pressure Adjustment5.6 Flow Chart of Capillary Tube PD pump5.7 External safety valve adjustment5 .8 Internal safety valve adjustment5.9 Engine lubrication5.1 Capillary tube: A capillary tube is a long, narrow tube of constant diameter. In the capillary tube refrigeration application, surface tension is not important. Pipe length limit from 1.0 m to 6 m and refrigerant capillary tube diameter limit from 0.5 mm to 3 mm. Due to the following two factors, pressure reduction in a capillary tube occurs: The frictional resistance offered by the walls of the tube the refrigerant must overcome. Compared to that of a liquid, the density of vapor is lower. As it flows through the pipe the average density of the refrigerant decreases. Increasing the acceleration or velocity of the refrigerant requires a pressure drop. 5.2 Priming: Liquid pumps can lose their priming and to start the pump you will need to prime the pump by adding liquid to the pump and inlet pipes. Loss of "first" ...