Automated control valve - Week 6.ppt

PRESSURE REDUCING AND REGULATING VALVES Multi component control loops Valve can also have two discs on one valve stem, which are also balances. It is called a double seat pressure balanced plugs. The high pressure medium enters between the two seats and exerts opposing forces on each of the seats ? * * PRESSURE REDUCING AND REGULATING VALVES Self contained pressure regulator has all of the control components needed in one valve. Automatically reduce supply pressure to a preselected pressure As long as the supply pressure is at least as high as the selected pressure. * * PRESSURE REDUCING AND REGULATING VALVES The principal parts: An upward-seating main valve that has a piston on top of its valve stem, An upward-seating auxiliary valve, A controlling diaphragm, An adjusting spring and screw. The pressure entering the main valve assists the main valve spring in keeping the reducing valve closed by pushing upward on the main valve disk. * * PRESSURE REDUCING AND REGULATING VALVES Some of the high pressure is bled to an auxiliary valve. ? The auxiliary valve controls the admission of high pressure to the piston. The piston has a larger surface area than the main valve disk, Open the main valve. ?? The auxiliary valve is ?controlled by a diaphragm. * * PRESSURE REDUCING AND REGULATING VALVES * * PRESSURE REDUCING AND REGULATING VALVES The control system below shows a supply service arrangement. The variable pressure sensing line is actually measuring the pressure exerted by the column of water above the sensing point of the variable pressure line to the water level. As the water level changes, the pressure will vary in the variable line. * * THANK YOU * * POWER EQUIPMENT  INSTRUCTOR:  ROBERT A. MCLAUGHLIN  ZAIL