Spirax Sarco RIM20, Инструкция по установке и обслуживанию, Страница: 10 / 132

IM-P198-05 MI Issue 2 10
2.8 Pressure measurement
The RIM20 rotor insertion flowmeters incorporate a solid-state pressure transducer isolated
by a 316L stainless steel diaphragm. The transducer itself is micromachined silicon, fabricated
using integrated circuit processing technology.
A nine-point pressure/temperature calibration is performed on every sensor. Digital
compensation allows these transducers to operate within a 0.3% of full scale accuracy band
within the entire ambient temperature range of -40 to 60 °C (-40 °F to 140 °F). Thermal isolation
of the pressure transducer ensures the same accuracy across the allowable process fluid
temperature range of -200 to 400 °C (-330 °F to 750 °F).
2.9 Flowmeter configuration
The RIM20 rotor insertion flowmeters has a sensing head which contains the turbine rotor,
temperature sensor, and pressure tap.
The pressure sensor is located in the pressure transducer housing between the stem and
electronics housing.
The meter is installed through a full port block valve and mounting adapter having a clear,
cylindrical port diameter of 47.625 mm (1.875") diameter. It can be installed during system
downtime or using standard "Hot Tap" procedures.
The meter directly monitors the velocity at a point in the cross-sectional area of a pipe, duct,
or stack. The velocity at a point in the pipe varies as a function of the Reynolds number. When
a fluid flows through a pipe, the velocity generated is not constant across the diameter. The
fluid velocity varies across the diameter of the pipe creating a "Velocity Profile".
That is, velocities near the center of the pipe are faster than those nearer to the wall. In
addition, the velocity profile varies in concert with flowrate from the lowest to the highest
flows. Mathematical descriptions of this profile have been developed for over 100 years. By
knowing the velocity profile and the flowrate at a single point, the average flowrate can be
determined. The accuracy of the flowrate computation depends on adherence to the piping
installation requirements given in Section 2. If adherence to those guidelines cannot be met,
contact the factory for specific installation advice.
2.10 Multivariable options
The RIM20 model is available with the following options:
V, volumetric flowmeter;
VT, velocity and temperature sensors;
VTP, velocity, temperature, and pressure sensors;
VTEM energy output options;
VTPEM, energy options with pressure;
VTEP, external pressure transmitter input.
2.11 Line size / process connections
The RIM20 rotor insertion flowmeter can be used in line sizes DN50 (2") and greater and is
built with a compression fitting or packing gland design using 50 mm (2") NPT, or DN50 (2")
flanged connections (ANSI 150, 300, 600, PN16, 40, or 63 class flanges). The packing gland
design can be ordered with a permanent or removable retractor.