|Title of Invention||
LIQUID PISTON FLOW METER
|Abstract||Four valve flow meter wherein there is provided a thin tube with a drop of mercury, the direction of the flow is controlled so that the unidirectional flow is been converted to bi-directional flow, this is done by four valves, these four valves are placed on the four ends, that"s the two ends of the tube is connected with a pair of valves, this pair of valve has a valve on the upper side of the tube and other on the lower side, the top end is normally the input of the flow meter and the bottom end is normally the output end.|
|Full Text||FLOW METER
FIELD OF INVENTION
This invention relates to measuring technology. More particularly this invention relates to Flow meters. Further this invention is concerned with volume flow in order of Micro Volume flow / Min.
The following specification describes various kinds of techniques used for the measurement of flows of substances like liquids, gases & solids. More particularly the description, which follows the various systems known in the art, and the deficiencies in the prior art. The object of the invention is to overcome the problem in general by way of reduction of cost and improving the sensitivity.
SUMMARY OF INVENTION
The inventor has made great effort to provide a system, which meets the requirement of the industry and overcome the problem associated in the prior art.
To achieve the above object according to first aspect and feature of the present invention there is provided a method and a system to improve efficiency, accuracy, sensitivity, reliability.
According to second aspect and feature of the invention in addition to the first feature the invention comprises of a system, which is unique, rugged efficient, economical and compact.
At the outset of the description, which follows, it is to be understood that ensuring description only illustrates a particular form of this invention, However, such particular form is only an exemplary embodiment without intending to imply any limitation on the scope of this invention. Accordingly, the description is to be understood as an exemplary embodiment and reading of the invention is not intended to be taken restrictively.
The above and other objects features and disadvantages will be clear from the following description of preferred embodiment taken in conjunction with accompanying drawings.
The foregoing description is outlined rather broadly preferred and alternative feature of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing and modifying other structures for carrying out the sajne purposes of the present invention. Those skilled in the art should realize such equivalent conception do not depart from the spirit and scope of the invention in its broadest form.
A Four valve flow meter comprising of four valves positioned on both ends of the Mercury column, one on the top and another at the bottom on either sides, wherein there is provided a thin tube with a drop of Mercury positioned bisymmetrically between the four valves
BRIEF DESCRIPTION OF DRAWINGS
The accompanying drawings are intended to provide further understanding of invention and are incorporated in and constitute a part of invention. The drawings illustrate an embodiment of invention and together with the description illustrate principle of invention.
The drawings should not be taken as implying any necessary limitation on the essential scope of invention.
The drawings are given by way of non-limitative example to explain the
nature of the invention.
For a more complete understanding of the instant invention reference is now made to the following description taken in conjunction with accompanying drawings.
The various feature of novelty which characterizes the invention are pointed out specifically in the claims, which are part of the description. For a better understanding of the invention, its operating advantage, specific objects obtained by its use, reference should be made to the drawings and the descriptive matter in which they are illustrated and described as preferred embodiments of invention.
Referring now to drawings, where like numerals designate identical or corresponding parts throughout the referred views. Now the invention will be described in detail with reference to drawings, which accompany the description. Figure 1 of the drawings shows in line diagram ultrasonic flow meter Figure 2 of the drawings shows in line diagram- Doppler Effect flow meter Figure 3 of the drawings shows in line diagram- electro magnetic flow meter Figure 4 of the drawings shows in line diagram- Positive displacement flow meter
Figure 5 of the drawings shows in line diagram- Four Valve Flow Meter according
to this invention
Figure 6 of the drawings shows in line diagram- Direction of flow of mercury from
right to left.
Figure 7 of the drawings shows in line diagram- Direction of flow of mercury from
left to right.
Let the inner area of the tube be -' Ai' M2 Let the speed of flow be - 'Sf M/Hr Then the flow rate «Fr' = Ai*SfM3/Hr
DETAILED DESCRIPTION OF AN EMBODIMENT OF INVENTION WITH RESPECT TO RELATED ART Different techniques used for measuring the flow Speed of the flow
Let the inner area of the tube be -' Ai' M2 Let the speed of flow be - 'Sf M/Hr Then the flow rate «Fr' = Ai*SfM3/Hr Types of flow using speed measurement are Ultrasonic flow meter, Electromagnetic flow meter, hot wire and Laser Doppler.
Difference in pressure
This type of flow measurement is based on Bernoulli's theorem. According to it, the algebraic sum of the pressure head, velocity head and the elevation head at one point will be equal to their sum at another point along the flow, if the loss due to the friction between the two point is properly accounted for.
Bernoulli's equation for a flow of incompressible fluids between any two point 1 & 2 may be written as
Where P - pressure, 1 - specific weight, V - linear velocity, Z is elevation. Then the suffix 1 & 2 refers to the point of measurement.
There are many flow meters using this difference in pressure to measure to flow, like orifice plate, venture tube, flow nozzles, dall tube, Pitot tube.
These types normally measure the total volume of flow. The working principles depend on a mechanical cycle movement associated with port openings and closings of the moving components, which permits a fixed quantity of fluid to be delivered at each cycles.
In application like irrigation, draining and sewage treatment, it is easy to construct open channel flow meter. Flow rate can be measured by wires, formed by shaped plates fixed in the channel or flumes, which are formed by shaping the section of the channel. Flow rate is measured by the help of the level of liquid flow through the channel. The level of the level of the liquid, is mechanically measured or by using an ultrasonic duct gage or by using an air bubbler system.
There are many flow meters presently available to measure the flow. Most of these sensors are fully electrical machines, so as its sensitivity and accuracy increases. But as its sensitivity increases its cost also increases. The instrument measures the velocity of the flow and calculates the flow rates. In some case
pressure difference or even the number of displacement for a fixed amount of flow is measured and so the flow rate is calculated.
High Sensitive flow meters
Ultrasonic flow meter Electromagnetic flow meter Positive displacement flow meter Laser Doppler flow meter
Ultrasonic flow meter:
Pressure variations travel through a fluid at the velocity of sound relative to the fluid. If fluid is in motion with certain velocity, then the absolute velocity of pressure disturbance propagation is the algebraic sum of the two. The term ultrasonic refers to the pressure disturbances (usually are short bursts of sin waves) whose frequency is above the range audible to human hearing, which is 20 to 20000Hz.
The ultrasonic flow meter operates on the principle that the velocity of sound is a fluid in motion is the resultant of the velocity of sound in the fluid at rest plus or minus the velocity of the fluid itself.
This principle can be used in two ways.
1. The travel time difference method
Ultrasonic waves are transmitted in opposite directions of the flow and the difference in travel speed is measured.
2. The beam deflection method
The deflection of an acoustic beam transmitted across the flow js measured.
Ultrasonic Doppler flow meter
The third type of flow meter using ultrasonic is based on Doppler principle. This type of meter will not work unless there are enough reflecting particles or air bubbles. The transit on the other hand requires relatively clean fluid to minimize signal attenuation and dispersion.
In this type of flow meter the sound waves are projected along the flow path and the frequency shift in the signal returned from scatterers in the fluid is measured.
The well-known Doppler Effect is that whenever there is a relative motion between the sources of a sound wave or an electromagnetic wave and the receiver or a reflector of those waves, the frequency of the wave changes.
For example an observer standing near a railway track will hear the whistle more and more shrill pitched as the whistling train approached the observer and low.
The receiver is also mounted on the same transducer block. This transducer block will be outside the pipe, which makes the installation easy. In another method the transducers can be kept flush with the inside wall of the pipe which is known as 'wetted type' ultrasonic flow meter.
ELECTROMAGNETIC FLOW METER Working Principle
One of the non-intrusive methods of flow measurement is by using electromagnetic flow meter. The basic principle of operation of an electromagnetic flow meter is the generation of electromotive force due to induction same as that of electric generator. That is whenever a conductor of length T moves with a velocity
For example an observer standing near a railway track will hear the whistle more and more shrill pitched as the whistling train approached the observer and low.
The receiver is also mounted on the same transducer block. This transducer block will be outside the pipe, which makes the installation easy. In another method the transducers can be kept flush with the inside wall of the pipe which is known as 'wetted type* ultrasonic flow meter.
ELECTROMAGNETIC FLOW METER Working Principle
One of the non-intrusive methods of flow measurement is by using electromagnetic flow meter. The basic principle of operation of an electromagnetic flow meter is the generation of electromotive force due to induction same as that of electric generator. That is whenever a conductor of length T moves with a velocity perpendicular to a magnetic field B; an e.m.f 'e' is induced in a mutually perpendicular direction which is given by
eHBlv volts Where
B = magnetic flux density (Wb/m2)
1 = length of conductor (m)
v * velocity of the conductor (m/s) The volume flow rate Q is given by
Q - (TC12/4) v Where,
Suitable amplifiers are necessary to amplify the signal. The input impedance of the amplifiers are to be properly selected since the liquid resistance between the electrodes of low conductivity liquids is quite large.
Advantages of electro magnetic flow meter
a) The obstruction to the flow is almost nil and therefore this type of meters can be used for measuring heavy suspensions, including mud sewage and wood pulp.
b) There is no pressure head loss in this type of flow meter other than that of the length of straight pipe, which the meter occupies. Therefore large water pipelines where low head loss is essential this meter can be used.
c) EM flow meters are available from 3mm to 3m diameter hence the flow range that can be metered with this is larger than other types.
d) EM flow meters are not very much affected by upstream flow disturbances, unless severe asymmetry of velocity profile is present.
e) They are practically unaffected by variation in density, viscosity, pressure, temperature.
f) The output is essentially linear.
g) These meters can be used for bi-directional flow or pulsating should be at least 10 times lower than the frequency of excitation of the fields.
h) Special meters for measuring the flow of some molten metals are available, although it may be necessary to go to a specialist manufacturer for these.
i) Highly special electromagnetic flow meters are available for measuring flow in human blood vessels.
Disadvantages of electro magnetic flow meter.
a) These meters can be used only for fluids, which have reasonable
For fluids of electrical conductive 10 microseism/cm flow meters can be easily made. But for electrical conductivity in the range of 0.1 microseism/cm. Electro magnetic How meters can be constructed with sophisticated and costly electronic devices. Hence water based liquids can be handled comfortably but hydrocarbons and most other organic liquids cannot be metered easily.
b) The modern electromagnetic meters are considerably better than those
of a few years ago, but accuracy is only in the range of+-1% over a flow rate range
A few manufacturers claim an accuracy of+-0.5% over a 5:1 range but these are expertise.
c) The size arid cost of the field coils and circuitry do not increase in
proportion to their size of pipe bore. Consequently small size meters are bulky and
POSITIVE DISPLACEMENT METER
The positive displacement* meter for liquid service is made up of a measuring chamber and a metering section between the inlet and outlet connections. It splits the flow of liquid into separate measured volumes based on the physical dimensions of the meter and counts them and totalizes them. The unit of flow is the product of the piston or vane displacement and cross-sectional area of the measuring chamber. The fluid follows a fixed path in the measuring
chamber and on each revolution of the meter is filled at the inlet and discharges at the outlet. The total quantity of the fluid passing through the meter in a given time is the product of volumes of the chambers and the number of fillings. When the chamber is filled once for each revolutions of the mechanism then the number of filling is equal to the total number of revolutions of the mechanism. In such meter volume rate of flow is equal to the volume of the measuring chamber and the number of revolutions per unit time.
i. High quality positive displacement meters will measure total liquid volume with high accuracy over a wide range of flow rates and are very reliable over long periods (applications as filling station petrol pumps).
ii. They will meter moderately viscous liquids accurately as long as they are calibrates with right liquid and in some models the dials can be adjusted to read correctly with the liquid concerned.
iii. The direct dial readout makes for simplicity of operation, enabling them to be used by unskilled operators.
iv. They are not affected by upstream flow disturbances and so can be installed very close to a bend without loss of accuracy.
i. They are bulky, especially in the larger sizes, ii. They have a high head loss.
iii. They are viscosity-sensitive but to a lesser extent than many other
types of meter, iv. They can be damaged by dirt particles and filtration of the inflowing
liquid is therefore usually necessary, v. They are more accurate types but are rather expensive, vi. If they seize up they completely block the flow, vii. They are suitable over only a limited range of pressure and
temperature, viii. Some types will introduce pulsation into the flow.
A flow meter senses the flow by calculating the velocity of flow through a tube. To have a high sensitive flow meter, if the inner diameter tube is thinner then the flow velocity will be higher, and if the velocity is higher then the sensor output of the velocity will also be higher.
In four valves flow meter there is a thin tube with a drop of mercury. The direction of the flow is controlled so that the unidirectional flow is been converted to bi-directional flow. This is done by four valves. These four valves are placed on the four ends, mat's the two ends of the tube is connected with a pair of valves. This pair of valve has a valve on the upper side of the tube and other on the lower side. So totally there are four valves and are named as la, lb, 2a and 2b where the valves on the upper side of the tube are named with "a" and lower side are named with "b", and "1" and "2" are named by its left end right end of the tube as shown in the figure. The top end is normally the input of the flow meter and the bottom end is normally the output end.
The flow is directly or indirectly connected to the input of the FVFM (direct and indirect connection will be dealt later). There are five sensors in the thin tube to sense the flow, where the first and the last sensor are the extreme ends. Initially valve "la" and "lb" are opened and "2a" and "2b" are closed so the flow is from left end to right end that's from sensor 1 to sensor 5. Initially when there is a flow, the flow passes through valve "la" and pushes the mercury. This makes the mercury to move and so the makes the substance on the other side of the mercury of flow out through the valve "lb". When ever the mercury crosses a sensor a signal it given to the controller and it takes the action. When the sensor crosses sensor 5, the controller sets open the valve "2a" and "2b" and closes the valve "la" and "lb". When this is the movement of the mercury is from right to left, that's from sensor 5 to sensor 1. So the mercury is moved by the flow, form sensor 5 to sensor 1. When it reaches sensor -1 again controller changes the valve position by opening valves "la" & "lb" and closes valve "2a" and "2b". So again the mercury starts moving from sensor 1 to sensor 5.
This is a contact flow meter. Here, only non-reactive to mercury fluids can be used and either non-conductive or transparent liquid can be used. As per the four-valve flow meter, there are four valves to control the direction of the fluid flow and the fluid is directly sent into the apparatus, which moves the mercury. This is the simplest and more accurate, but the fluids can change the property of mercury so that if mercury brakes into pieces, then it won't stick together. So here vibration should not occur and if mercury breaks then the apparatus should be changed.
Conductive or transparent and non-reactive liquid flow.
All gases flow Advantage
Very Sensitive Disadvantage
Breaking of mercury in liquid
A Lead sense can be used to identify the position of the mercury. Here two wires are placed on the wall of the mercury column, were one lead is given supply and other is left open. When the mercury touches these two leads a short circuits is been created and this short circuit is used to identify the position of the mercury.
In four-valve flow meter in the mercury column the mercury is directly or indirectly made to flow by the flow itself. And as the mercury flows in a thin tube the distance moved for a unit flow will be very high and this reduction of size doesn't directly affects flow. And sensing the flow of mercury is very easy. So by using an accurate sensor the flow rate can be sensed accurately. And will be the cheapest among the sensitive low level flow meter.
For sensing the flow of mercury lead sensors are been used. Sensors placed at equal distance are mounted in the thin capillary tube, where mercury flows. These five sensors output is given to a controller, which calculates the time interval between any two sensors to be set. This time duration is been divided with the volume in between the two sensors, so as to calculate the flow rate.
The controller is also used to control the direction of the flow by opening or closing the solenoid valves. To do this the out put of the controller is used to trigger a relay, which in turn energizes or de-energizes the solenoid coil, which helps to control the direction of the direction of flow.
The controller is also used for calculating and thereby displays the flow rate. A display circuit has been interfaced with the controller for the display of flow rate in micro liters per second.
The flow sensed here is not continuous. Since the sensors are kept apart from one another the intermediate position can't be measured. So even though due to this the output is not pulsed, but the out put of the sensor is not continuous. To over come this problem, sensor that can track the position of mercury continuously should be used. As mercury is conductive to both magnetic and electrical field inductive or resistive or capacitive sensors can be used.
In this project testing was done, by blowing air into the input of the four valve flow meter. On doing so the mercury started moving and sensor sensed the movement of the mercury. The output of the sensor was given to the controller and the controller took action according to the position of the mercury and calculated the flow rate. The display unit acquired this data and displayed. And the control action by the controller to the relay was also done. These were verified successfully.
LVDT sensor can also be used. This sensor will be very sensitive for sensing the position of mercury if the length of coil should be less. By having much number of coils and considering the position of mercury, consecutive three coils can be selected as LVDT primary and secondary coils.
By having a valve which can satisfy the four valves in four valve flow meter that can be replaced so that the flow meter has only one valve.
In the future the flow meter can have just one operating solenoid coil to control the flow. Not only LVDT sensor but also resistive and capacitive sensor may be used. This technique can be used not only to sense low level flow but also to sense high level flow and even for measuring pressure.
Though an embodiment of the invention is explained with reference to four valves, the concept of the invention can be explained to six valves also. In such case the advantages are as follows.
In four valve flow meter, the to and fro motion of the mercury in the mercury column is been converted to a circular movement by modifying the mercury column to a circular one and by having two valve in addition to it. This circular motion of mercury in a circular mercury column reduces the end error in a straight mercury column as in four-valve flow meter and also increases to volume of flow to some extent.
The invention has been explained in relation to specific embodiment. It is inferred that the foregoing description is only illustrative of the present invention and it is not intended that the invention be limited or restrictive thereto. Many other specific embodiments of the present invention will be apparent to one skilled in the art from the foregoing disclosure. All substitution/ alterations and modification of the present invention which come within the scope of the following claims are to which the present invention is readily susceptible without departing from the spirit of the invention.
The scope of the invention should therefore be determined not with reference to the above description but should be determined with reference to
appended claims along with full scope of equivalents to which such claims are entitled.
This type of flow meter is based on the speed of flow. Here the flow is made to flow through a tube with a fixed inner diameter. By calculating the speed of flow the distance occupied by the flowing substance for a unit time can be calculated.
1. A Four valve flow meter comprising of four valves positioned on both ends of the Mercury column, one on the top and another at the, bottom on either sides, wherein there is provided a thin tube with a drop of Mercury positioned bisymmetrically between the four valves.
2. A Four valve flow meter wherein the unidirectional flow of Mercury in the Mercury column due to the flow of the substance is converted to bidirectional flow of the Mercury in the Mercury column by these four valves and this leads to reduction of the Mercury column.
3. In Four valve flow meter the volume flow of solids liquids and gases can be measured wherein for measuring the volume flow rate of solids, the solid substance is placed in a sealed tank having an outlet and an inlet for the air to pass in, which is being connected to the outlet of the Four valve flow meter and as the flow starts, air is being sucked in through the four valve flow meter for filling the empty space created in the sealed tank due to the flow and the air flow in the sealed tank through the Four valve flow meter is equal to the substance flowing out of the sealed tank and so the air flown into the sealed tank through the four valve flow meter is measured.
4. Four valve flow meter wherein in the Mercury column between the four valves, the Mercury is directly or indirectly made to flow by the flowing substance itself and as the Mercury flows in a thin tube the distance moved for a unit flow will be very high and this leads to the reduction of the diameter of the Mercury column and this does not affect the flow or flow head of the flowing substance.
5. A Four valve flow meter wherein for sensing the flow of Mercury, lead
sensors are being used. The sensors placed at equal distance are mounted in
the Mercury column where the Mercury flows and the output of the sensors
are fed to a controller which calculates the time interval between any two
sensors to be set, this time duration is being divided with the volume in
between the two sensors so as to calculate the flow rate.
6. A Four valve flow meter wherein the controller is also used to control the
direction of the flow by opening or closing the solenoid valves. Such that
the output of the controller is used to trigger a relay, which in turn energizes
or de-energizes the solenoid coil which helps to control the direction of flow
of Mercury in the Mercury column.
7. A Four-valve flow meter wherein the Controller is also used for calculating
and thereby displaying the flow rate, the display circuit has been interfaced
with the controller for the display of flow rate.
8. A Four valve flow meter wherein LVDT sensors can also be used.
|Indian Patent Application Number||592/CHE/2005|
|PG Journal Number||32/2010|
|Date of Filing||18-May-2005|
|Name of Patentee||PETER RAJ. J|
|Applicant Address||D-121, T.P. ROAD BLOCK 12, NEYVELI-3 TAMIL NADU S. INDIA.|
|PCT International Classification Number||G01F9/00|
|PCT International Application Number||N/A|
|PCT International Filing date|