The flow element for inlet water flow shall be a laboratory-calibrated flow nozzle.
All differential pressure elements shall be completely provided with insulation or process valves, 3way manifold and drainage valves incorporated with the instrument.
Flow meters of positive displacement shall be used for measurement in gas or fuel oil.
For industrial water service, volumetric meter Woltmann mill type shall be used; body material shall be painted cast iron, connection shall be flanged with suitable rating; double magnetic transmission shall be provided so that only the mill is in water contact; the interface with DCS shall be a pulse transmitter type with voltage free type contact.
For demi-water service, volumetric meter Woltmann mill type shall be used; it shall be of the same as above requirements but, with body internal coating, suitable for demi-water application.
In general, feed-water flow meters will be temperature compensated when the water temperature is greater than approximately 120 °C; steam flow meters shall be always temperature and/or pressure compensated; air flow measurements will be temperature compensated. Compensation calculations are performed by the DCS.
Where compensation by density, temperature or pressure has to be performed, these
measurement shall be taken next to the installed flow meter.
Invoicing meters, shall have to be mounted with all adequate elements for his function. They’ll have to be documented with calibration certificates of an approved laboratory. His precision should be comprehended between ± 0.1 %.
Flow nozzles and orifices are installed in meter runs having twenty (20) diameters minimum of straight pipe upstream and five (5) diameters minimum of straight pipe downstream of the flow element.
Nozzles and Venturi flow type will meet +2.0% and orifices meet a maximum of +1.5% of reading accuracy over a 4:1 flow turndown ratio without laboratory calibration when installed in the meter runs.
The bodies of the meter shall be made of a material resistant to the corrosive (if any) effect of the process fluid where it is installed.
Meter-runs are of the same material and design strength as the pipe called out in the document 507E06/L8(VVA)000-33M002 (Piping Specification); straightening vanes are not used to shorten required lengths of straight pipe
Sizing, construction and installation of the flow elements shall conform the recommendations of ISO 5167 standard and. orifice metering flanges shall be minimum ANSI 300 Class; beta ratios are maintained between 0.3 and 0.7.
总共有7，8段好像，100分寻高手翻译，
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