Thermal Mass
Mass Flow Technology for Process & Environmental Measurements.
Principle - The Kurz Mass
Flow Meters uses the well proven Kurz thermal convection
mass flow measurement method by detecting the heat transfer
from the heated RTD sensor (Rp) referenced to the temperature
of the ambient gas stream RTD sensor (Rt). A constant temperature
difference between the heated sensor and the temperature
sensor is maintained by a modified. Wheatstone Bridge circuit
in which the heated sensor is the controlled element.
This provides unexcelled speed of response and the many
other advantages of constant temperature thermal anemometry.
The microprocessor-based electronics measures the heat transfer,
computes the standard velocity and ambient gas temperature,
and allows the user to configure and set-up and the flow
meter to fit all flow requirements. Display screens are
east-to-use and provide all the flow, temperature and diagnostic
information.
Kurz was the first to develop all-welded dual-sting sensors
that have the following important features
:
- Direct mass flow measurements without the need for
pressure or temperature correction.
- High-level electronic signal output.
- Exceptional low speed sensitivity.
- High turn-down ratio up to 1000:1
- Nearly constant percent of reading accuracy.
- Low cost, easy installation.
- Negligible pressure drop.
- Large temperature and pressure range.
- Solid-state, no moving parts, shock resistant.
- Very good repeatability.
- Fast response to velocity and ambient temperature
changes.
- Insensitivity to non-axial velocity components.
- Two wire loop-powered operation.
Kurz offers three types of thermal mass flow elements
:
- In-line Mass Flow Elements :-
Kurz Series 502, 510, 522 UHP, 532, etc.
- Single-Point Insertion Mass Flow Element
:- Kurz Series 452, 410, etc.
- Multi-Point Insertion Mass Flow Elements
:- Kurz K-BAR 24, etc.
In-Line Mass Flow Elements
These are generally used for small pipes and
situations in which a higher accuracy required. These
are designed to include the proper upstream and down
stream dimensions, screens and nozzles as appropriate,
so that the mass velocity profile within the in-line
flow element is flat and invariant.
Single-Point Insertion Mass Flow
Elements measure
The velocity at the point in a duct or stack in which
they are inserted. Therefore, the user's duct serves as
the flow body and the output is dependent on the
relationship between the average velocity and the
measurement location velocity. For pipes larger than
about 2-1/2 inches, a single point insertion mass flow
element is generally used because of its simplicity and
lower cost. These units are very attractive as they can
easily be inserted under flowing conditions.
Multi-Point Insertion Mass Flow Elements
Are used in larger ducts in which each sensor is
placed at an equal area location in the duct, pipe or
stack.
Mass Flow Computers
The Kurz Series 155 Mass Flow Computers operate most
Kurz products. The microprocessor serves as a flow
computer incorporating the sensor calibration, duct
area, sensor diagnostics, display, outputs, variable
velocity correction factors, redundancy, etc.
Typical applications includes:
- Process Gas measurements in Chemical and
petrochemical plants.
- Combustion air measurement for large utility
boilers, co-generation plants, and other combustion
processes.
- Mass flow measurements for stack effluent
monitoring and incinerators.
- Aeration air, digester and chlorine gases in
municipal waste water treatment plants.
- Semi-Conductor process gas measurements and
control, including Ultra-High Purity gases.
- HVAC applications involving ventilation and
temperature control.
- Air sampling in Nuclear Power Plant and DOE
facilities.
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