Field-Mounted Instruments Sample Clauses
Field-Mounted Instruments. Instruments shall be mounted so they may be easily read and serviced and all appurtenant devices easily operated. Installation details for some instruments are indicated on the drawings. Unless otherwise indicated on the drawings, instruments that include local indicators shall be mounted approximately 5 feet above the floor and shall be oriented for ease of viewing. Transmitters shall be mounted on corrosion-resistant pipe supports suitable for floor, wall, or bracket mounting.
Field-Mounted Instruments. Unless otherwise specified or approved by Company, all parameters (e.g., pressure, flow, level, temperature) for indication on local control panels or control panels remote from the point of measurement shall utilize smart transmitters which convert the measured parameter into a standard DC electrical signal. All field mounted electrical equipment shall be indoor (NEMA 12 or equivalent) and suitable for the local corrosion conditions. Instruments and enclosures shall be explosion proof if located within 15 ft of a natural gas line flange. Pneumatic instruments shall be weatherproof (NEMA Type 3S or equivalent). All transmitters shall be provided with isolation valves and test connections. For high-pressure systems (above 200 psi) manifold blowdown pipe work or plugs shall be provided. Switches for pressure, temperature and level monitoring shall be of the heavy-duty type with double pole changeover contacts. Contacts shall be rated to suit their required duty. Mercury switches shall not be used. Boiler feedwater flow elements shall be ASME flow nozzles. These nozzles shall be flow tested and provided with flow calibration certificates. Orifice plates shall be paddle type square edged concentric for clean fluids. Differential pressure instruments shall be close-coupled to the orifice taps where practical. Orifice plate sizing, orifice plate construction, and the design of associated meter piping shall conform to the requirements of ASME MFC-3M or AGA 3. The orifice plate tag number and information shall be stamped on the upstream side of the paddle handle. Orifice plates shall be made of a material suitable for the service application. The orifice plate beta ratio (d/D) shall be between 0.3 and 0.7 for flow control measurements. Orifice meter accuracy shall conform to ASME MFC-3M or AGA 3 specifications. Turbine meters, elbow meters, positive displacement meters, magnetic flow meters, venturi flow tubes, pitot tubes, annubars, coriolis mass flow meters, vortex meters, and ultra-sonic flow meters may be used.