và UL 795 comrnerclaHnduslrlaJ khí nóng 8 (JJipment. Vì vậy, họ excsllentfor convertlf "Q hệ thống 10 nhiên liệu differenl Th. R4140lls hoàn hảo cho L. pQrading 10 một hệ thống đáp ứng các Doanh nghiệp bảo hiểm rủi ro Nhà máy Mutual và Induslrial (trước đây là FIA) reqJiretTlQ" LTS (Tham khảo | Limits Controllers . Ị end Interlocks i PRESSURE CONTROLLERS A pressure controller is a device hat monitors the pressure of steam air gases or liquids. An internal diaphragm or bellows responds to pressure changes and through a mechanical linkage actuates a switch or potentiometer to keep the pressure within predetermined limits. Pressure controllers are commonly used on steam boilers and hot water heating systems In gas burner systems and in oil burner systems. Honeywell pressure controllers available for use In these systems will be described in the following sections. Installation procedures peculiar to each system will also be discussed. PRESSURE CONTROLLERS USED ON STEAM BOILERS AND HOT WATER HEATING SYSTEMS ------------- The pressure controllers discussed in this section can be used with steam air noncombustible gases or fluid noncorrosive to the pressure sensing element. They provide operating control or limit protection depending on the controller model and wiring hookup Figs. 3-7 . LOCATION AND MOUNTING When used with steam boilers always mount the controller above rhe waterline in the boiler. A steam trap must always be connected between the controller and the boiler Fig. 11 to prevent boiler scale and corrosive vapors from attacking the diaphragm or bellows. The loop on the steam trap must always be perpendicular to the face of the controller. If the loop is parallel to the controller expansion or contraction of the loop will tip the controller and cause the switch to operate inaccurately. The controller can be mounted 1 alongside the pressure gauge 2 in a fitting on the boiler provided by the manufacturer or 3 at a remote location in case of excessive vibration. When making pipe connections use pipe compound sparingly to seal the joints. Excess pipe compound may clog the smalt hole in the fitting and prevent the controller from operating properly. PRESSURE controller V t- INCH BLACK IRON PIPE WITH I NPT EXTERNAL L k TrtftEAOS ON BOTH ENDS imc FIG. 11 -
