The Calibrating System of Fluid Flow Meter based on

The Calibrating System of Fluid Flow Meter based on
Proceedings of 2012 International Conference on Mechanical Engineering and Material Science (MEMS 2012)
The Calibrating System of Fluid Flow Meter based on
Lab VIEW
Jixin Zhou
Faculty of Electrical Engineering,
Tianjin Electronic Information Vocational Technology College, Tianjin, China
zhoujixin@126.com
used to ensure liquid flow is stabilization in pipe test section
( the liquid flow pipeline including the straight section for
installing flow meter ) ; a work containers and some
temperature transmitter used to measure liquid quantity
through the flow meter in a certain period of time;some water
media for emptying or weighing container and pipeline;some
drain valve used to return water media to the storage device;
some commutator used to regulating the flow of fluid in a test
pipe, so as to ensure the flow calibrating device working
according to a predetermined program;and a control and
management system used to measuring time interval and the
flow meter pulse number, ensureing the liquid quantity、
time、output signal of be detected flow meter are synchronous,
also have automatic calibration, data storage, print statements
and other functions .The specific mechanical structure as
shown in figure 1.
Abstract—On the basis of researching the fluid flow meter
calibrating method and device, this paper has designed a set of
flow meter calibrating system which based on LabVIEW
software. It mainly introduces the hardware device, software
control system and influence factors of precision test. The system
use the software processing method for compensating the
measuring error, improve the accuracy of system, and reduce the
cost of system.
Keywords-LabVIEW,flowmeter ,calibrate ,commutator
I.
INTRODUCTION
In the industrial production, the flux is a parameter which
is often detected. With the development of science and
technology, the accuracy requirements of flow measurement
are also getting higher and higher. In order to ensure accurate
measurement, flow meter in before they leave the factory,
using, and maintenance after using must be performance
testing or calibrating. This paper introduce a flow meter
calibrating device which be used in factory and have lower
manufacturing cost, higher working efficiency.
II.
OVERALL
DESIGN
We have a way to test and Calibrate flow: We inject liquid
to a container continuously with a steady flow of Q, and write
down the accurate starting time T1and stop time T2. At the
same time, we accurately measure liquid number( Qm or Qv )
accumulated in container of△ t= T2- T1 interval, then you
can calculate the average flow. To achieve this process a set of
device includes: a device used for liquid storage ;a device
Figure 1. Mechanical structure drawing
III.
This control system use industrial computer equipped with
multifunctional data card. This type of control can be shared by
multiple calibration pipeline. It use the industrial control
computer as upper machine, multi-function data card and a
simple control circuit board as lower machine. It through the
interactive information between the data acquisition card and a
circuit control plate control actuator and collect the input signal.
It deposit, analyse and compute collection of data by industrial
control computer, then give the output results. The control
system based on LabVIEW software has a friendly interface,
and its operation and monitor system is more convenient. It
also have lower cost and higher reliability.
© 2012. The authors - Published by Atlantis Press
HARDWARE DESIGN
The calibrating system needs to monitor temperature signal,
capture output signals of be calibrated flow meter, control the
Executive devices, and so on. Flow meter calibration system
hardware device consists of: industrial control computer、
multi-function data card 、 conversion circuits 、 executive
devices(drain valve, flow regulating valve, etc)、flow
meter 、 Temperature transmitter 、 and man-machine
interactive equipment (keyboard, mouse and printing
equipment etc.), some equipments used to providing the
necessary power of the system itself and flow meter or other
anti-jamming device which be used to ensure the reliable
operation of the system. The system diagram as shown in
Figure 2 .
187
The multi-function data card can made the signals to the
A/D conversion, D/A conversion , digital IO control, and sent
the signal to the IPC in the last. It used the software to process
data and complete hardware and computer interaction.
degree of the regulating valve; then, it measure flow rate value
at fast and compare the flow rate value with a desired flow rate
value. The loop exits until achieving the verification accuracy
or exceeding the cycle number of times.
EXPERIMENT DATA AND ERROR ANALYSIS
V.
Based on analyzing the calibration principle and influence
of the testing accuracy, we found that the system error from the
error of the standard container or the timing error of sampling
the flow meter which to be detected. The standard container
error is accredited by specialized national metrology institute,
so the error is to meet the requirements. Therefore, flow meter
sampling time error is the main factor affecting the accuracy
and reliability of the calibration system. The commutator is the
only equipment which can appear the time error in the entire
test process. We make use of flow meter verification method
for commutator of verification. The verification method is as
follows: We measure according to the flow meter's calibration
method and record workload readings B11, the measurement
time t11 and flow meter pulse number N11. We commutated
commutator m times in substantially the same time and t11,in
the same time, recorded scales or cumulative reading values
B21, cumulative measurement time t21 and the accumulated
pulse number N21 of flow meter. We repeated n times of test
and recorded B1i, B2i, t1i, t2i, N1i and N2i ( i=1, 2, ...
n ).Time interval:
Figure 2. system diagram
IV.
SOFTWARE DESIGN
A. Summary
Flow meter Calibration is a tedious and complex work. In
order to ensure the accuracy of collecting, output value of
being calibrated instrument under each flow point must be
calibrated repeated, which is bound to make use of the
computer for automatic acquisition. However, traditional
computer acquisition methods must write complicated
hardware interface procedures and data processing procedures.
Software system using the traditional method of setting up a
computer can take up a lot of time in the development of the
instrument. We take advantage of the virtual instrument which
increasingly apparent advantage in the field of data acquisition
to overcome the traditional acquisition methods defect.
ti 
In accordance with the requirements of the verification
system, the system software is in modular structure. It made
real-time data as the core to design many function module just
like pipe set、 test、 data management and so on. It also is
able to achieve real-time data display, have the settings to
modify instrument parameters and some functions just like
data analysis, data storage, error information display and so on.
Friendly operator interface of the system implement guidance
system structure and easy to be operated.
t1i N 1i N 2i  B1i B2i 
mB1i B2i t1i t2i   N1i N 2i  ()
Test data as shown in the table:
As can be seen from the experimental results are negative,
the experimental data show that the commutator error is
adjustable. We can set the delay time of the timer / counter to
adjust the measurement error. The measuring time interval was:
-0.007, -0.008, 0.032 at the point with the above-mentioned
data measurement method. Some data in the data set is positive
and another is negative indicating that the measurement error
can not be re-adjusted. In accordance with the test procedures
of various check flow meter test requirements, flow meter test
system worked to meet the steady flow conditions. We
computed and processed the flow meter test data are also in
accordance with the national Verification Regulation of items.
We made data linearity error and repeatability error analysis.
The calculation results showed that this test system is in full
compliance with the relevant requirements of the national
verification procedures.
B. Key technology
For the control and regulation of the flow in the pipeline is
a key part of the certification process. It can play a steady flow
and compensate flow deviation. Here we use a method of
automatically to control the flow. It adjusted the opening
degree of the actuator automatically according to the set of
flow points, using the method of successive approximation to
stable the flow rate value in the test pipe. The specific
operation is: First, it must set the opening range of the
regulating valve and take an intermediate value as the opening
TABLE I TEST DATA
Maximum
flow point
Minimum
flow point
Test status
Test items
measurement time t(s)
pulse number N(N/L)
reading values B(L)
measurement time t(s)
pulse number N(N/L)
reading values B(L)
Does not
switch
31.950
2982
147.049
235.100
2964
148.424
188
1
39.172
3547
149.664
237.132
2933
143.843
switch(5 times)
2
3
38.690
39.338
3495
3553
147.439
150.155
239.641
240.714
2952
2951
144.595
144.595
Time
interval
-1.498
-1.496
-1.492
-1.225
-1.315
-1.302
VI.
has a relatively high superiority.
CONCLUSION
The system based on IPC as a core. It was designed in
accordance with the basic theory of the flow test system and
the test function to achieve. Verification system acquiring the
input signal and controlling the output signal is achieved
through the interaction between multi-function data acquisition
card and control board. The IPC in the verification process
have automatic collection, processing test data, print out the
test results and other functions. System software in accordance
with the requirements of real-time design, based on functional
decomposition, study test software structure, flow diagram of
the main program and each function module descriptions and
flow charts. As a metrological verification device, the accuracy
is one of the most critical indicators. We analyzed the various
factors that affect the test accuracy, and focused on the greater
impact on the commutation time error and simultaneous
measurement of accuracy. The experimental results show that
the test system is feasible, both technically and economically
[1]
[2]
[3]
[4]
[5]
189
REFERENCES
Horritt,Matthew.Development and testing of a simple 20 finite
volume model of such-critical shallow water flow.International
Journal for Numerical in Fluids.2004,44(11):1231~1255
T.T.Espina,P.I.Osella.An Intelligent Ultrasonic Flowmeter for
Improved
Flow
Measurement
and
Flow
Calibration
Facility.Instrumentation
and
Measurement
Technology
Conference. 2001,3:1741~1746
Wright,J
D.Laboratory
Primary
Standards
in
Flow
Measurement:Practical
Guides
for
Measurement
and
Control,Spitzer,D.W.ed,The
Instrumentation,Systems,and
Automation
Society
Research
Triangle
Park
North
Carolina,2001,731~760
J.Hemp.A technique for low cost calibration of large
electromagnetic
flowmeters.Flow
Measurement
and
Instrumentation.2001,12(2):123~134
Miau J J,Wu.cw.A study on signal quality of a vortex flowmeter
downstream of two elbows out-of-plane.Flow measurement and
instrumentation,2002,13(3):75~85
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising