Calibration of a Venturi Flowmeter Group 4 Supervised by Dr Tian Nick Taylor __________________ (signed) Iain Howard __________________ (signed) Andrew Hardman __________________ (signed) Xu Yang __________________ (signed) School of Mechanical and Systems Engineering: Stage 1
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Calibration of a Venturi Flowmeter
Group 4
Supervised by Dr Tian
Nick Taylor __________________ (signed)
Iain Howard __________________ (signed)
Andrew Hardman __________________ (signed)
Xu Yang __________________ (signed)
School of Mechanical and Systems Engineering: Stage 1
Abstract
Flow Meter Calibration is a process to verify the flow rate of a system within industry. The flow rate is
known to be dependent on the pressure difference across a restricted and unrestricted piping. The
objective of this test is to familiarise flow meter calibration using a Venturi system and also determine the
relationship between the flow rate and the pressure difference when measured using a manometer. This
will allow a formula to be used to calculate a given flow rate.
An experimental test in which both the degree of height difference ( and Flow Rate (Q) are measured
using an Armfield F1-15 Bernoulli’s Thereom Demonstration Unit which suggests that the relationship
could be in the form of:
here the m in e alue is oun to e
m = 0.598 (uncertainty range of 0.5397 to 0.6718)
The value of m = 0.598 fell outside actual known value of m ≈ 0.5. The value was used to calculate the K
value which was found to be:
K = 0.0004 ±0.00005
Where:
Q = 0.0004 · H0.598
It was shown that the hypothesised equation of Q=K·Hm to be an appropriate formula to be used for Flow
Meter cali ration. As long as uncertainties where calculate an known limitations o Bernoulli’s Thereom
were considered.
Contents
List of Notations
1. Introduction
1.1 Background
1.2 Objectives
2 Theory
3 Apparatus & Method
4 Results
4.1 Data Uncertainties
5 Discussion
6 Conclusion
List Of Notations
V = Volume Unit: m3
H1 = Height at “a” Manometer Tu e Unit: m
H2 = Height at “e” Manometer Tu e Unit: m
∆H = Height difference (H1 – H2) Unit: m
Q = Volumetric Flow Rate Unit:
T = Time Unit: secs
k = Correctional Co-efficient Unit:
m = Arbitrary power
1. Introduction
1.1 Background
In differing industries there is a need to have a specific flow rate to be used as part of a system. To be
able to achieve this, calibration of the system will be needed. Flow meter calibration can be verified
using many differing systems. In our testing we will be using a Venturi system.
The Venturi system is ase on low continuity an The Bernoulli’s Thereom.
Included in the test will be familiarisation with using a Venturi system with connected manometers and
also analysising the resulting data.
Ha ing con ucte the test it will allow a iscussion on the results an also o Bernoulli’s Theorem.
1.2 Objectives
Correct procedural use of a Venturi System,
Show that experimental data justifies using a calibration formula of ,
Whilst including choice of a single best fixed value of the index value m whilst taking
into account estimate uncertainties an the theoretical alue o m ≈ 0.5, an
Quantifying the correction co-efficent, including its uncertainties to establish
accuracy of the test.
2. Theory
For a Volumetric Flow Rate measurement using a Venturi system, it should be possible to plot the
resulting data of Q vs ∆H and suggest that a power law formula would fit a trendline. To be able to
easily show this, plotting Ln (Q) vs Ln (∆H) would then give a linear trendline.
If this was shown to be true, then the resulting gradient of the line would indicate the relevant power
involved which would be unknown at the time.
This would then suggest:
If it is decided that the above is an acceptable function, then it would be necessary to identify a
correctional co-efficient (K).
To find the value of k, plotting Q vs should generate a graph with a straight trendline. The gradient
of the trendline would give the respective K value.
Once all the values are known comparison for its practical use of the system could be evaluated when
comparing the function with the well documented equation for Flow Meter calibration testing of:
However this would have to be critiqued as physical assumptions may not hold true for the particular
apparatus used in the testing and also uncertainties identified within the procedure.
3. Apparatus & Method
Apparatus which was used to conduct the calibration comprised of an Armfield F1-15 Bernoulli’s
Thereom Demonstration Unit (See figure 3.1) fitted on to an Armfield F1-10 Hydraulics Bench (See