FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
1. Title of the invention: A FLOW MEASURING DEVICE
2. Applicant(s)
NAME NATIONALITY ADDRESS
RAYCHEM RPG PVT. LTD Indian 463, Dr Annie Besant Road, Worli, Mumbai, Maharashtra
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

TECHNICAL FIELD
[0001] The present subject matter relates to devices for measuring a mass
flow of a fluid flowing through an enclosed channel, such as a pipe.
BACKGROUND
[0002] A flow meter is a device which may be used to measure an amount
of fluid which may be delivered through an enclosed channel, such as a pipe or a pipeline. Examples of fluids include, but are not limited to, gases such as natural gas and liquefied petroleum gas. Such flow meters, also referred to as gas flow meters, may be implemented for residential, commercial, and industrial facilities having a fuel gas supplied by a gas utility company. Such conventional flow measuring devices include diaphragm meters, rotary displacement meters, turbine meters, ultrasonic flow meters, and coriolis meters.
BRIEF DESCRIPTIONOF THE DRAWINGS
[0003] The following detailed description references the drawings, wherein:
[0004] FIG. 1 depicts a cross-sectional view of a flow measuring device,
according to an example;
[0005] FIG. 2 depicts a flow estimation unit which is to determine a flow
rate of a fluid, according to an example;
[0006] FIG. 3 depicts a cross-sectional view of a primary channel and a
bypass channel of a flow measuring device, according to an example;
[0007] FIG. 4 depicts a cross-sectional view of a primary channel and a
bypass channel of another flow measuring device, according to another example;
[0008] FIG. 5 depicts depicts a cross-sectional view of a flow measuring
device, according to an example.

DETAILED DESCRIPTION
[0009] The flow rate of fluids is typically measured through flow measuring
devices, such as diaphragm meters, rotary displacement meters, turbine meters, ultrasonic flow meters, and coriolis meters. A diaphragm meter generally has four measurement chambers formed by a moveable diaphragm. The diaphragms expand and contract, based on flow of fluid through the chambers. The movement of the diaphragm may be converted to a rotary motion of a crank shaft, which may then be used for driving a counter mechanism. The counter mechanism may give an indication as to the volume of fluid which may have passed through. A rotary displacement meter on the other hand may generally include two rotating impellers placed within a housing. The impellers are to rotate in opposite directions. Based on the rotation of the impellers, the amount of fluid which passes through a pipe or a similar channel may be estimated.
[0010] Other types of flow measuring devices may involve a variety of
different techniques for determining the amount of fluid which may be flowing through a channel. Irrespective of the approaches, such conventional flow measuring devices determine the volume of the fluid flowing through a channel based on the kinetic energy of the fluid flow. The kinetic energy is generally converted into another form of energy (such as rotational energy) based on which the flow rate of the fluid passing through the channel may be estimated.
[0011] Conventional flow measuring devices have their own limitations. For
example, diaphragm meters may develop leaks owing to numerous number of moving parts and also, being a polymer, there are chances of permeant-set in over long periods of time, owing to continuous operation. This may result in incorrect or erroneous readings. The rotary displacement and turbine meters have complex constructional features having a number of mechanical parts. Owing to the large number of mechanical components, the flow rate estimates may suffer from inaccuracy. Furthermore, a large number of mechanical parts may also tend to suffer from wear and tear, and may require periodic

maintenance, which may involve costs. Other types of flow measuring devices possess complicated mechanisms, and electrical components which makes such flow measuring devices expensive and complicated to use. In most circumstances, the flow measuring devices may have to be electrically powered through an external source, which in turn further adds to the costs related to the use of the conventional flow measuring devices.
[0012] Examples of a flow measuring devices for determining a flow rate of
a fluid flowing through a channel, are described. The flow measuring device includes a primary channel through which the fluid is transported. As may be understood, the primary channel may include a primary inlet port, which is to allow the ingress of the fluid. The primary channel may further include a primary outlet port, which allows the egress of the fluid from the primary channel. The primary channel may be any longitudinally extending enclosed channel, for example a pipe.
[0013] The flow measuring device may further include a bypass channel
which is coupled to the primary channel. The bypass channel is coupled to the primary channel in a manner, such that a bypass inlet port and a bypass outlet port are coupled to the primary channel. In an example, the bypass inlet port may be at a point which is upstream with respect to the direction of the fluid flow within the primary channel. The bypass outlet port, on the other hand, may be at a point which is downstream with respect to the direction of the fluid flow within the primary channel.
[0014] The bypass channel may further be provided with a first sensor
provided at the bypass inlet port, with a second sensor being provided at the bypass outlet port. The first sensor and the second sensor may be a temperature sensor or a pressure sensor. The first sensor and the second sensor are to detect a flow attribute manifesting at the bypass inlet port and the bypass outlet port. Examples of flow attributes include, but are no limited to, pressure and temperature. As may be noted, depending on the flow attribute to be detected, appropriate sensors may be used. It may be noted that the examples of the flow attributes are only indicative. Other examples of

flow attributes may also be used without deviating from the scope of the present subject matter.
[0015] Continuing with the present example, the primary channel may
further include a flow resistive element. The flow resistive element, amongst other aspects, is to introduce flow resistances to the flow of the fluid through the primary channel. As a result of the flow resistances introduced due flow resistive element, a certain volume of the fluid is directed to flow through the bypass channel. In an example, the flow resistive element may include passive elements such as vanes, baffles, porous sheet, or lining. In another example, the flow resistive element may be a turbine.
[0016] In operation, the fluid may be introduced into the primary channel.
The flow of the fluid in the primary channel experiences flow resistances due to the flow resistive element. Owing to the flow resistances, a volume of the fluid flowing through the primary channel is directed to flow through the bypass channel. As the fluid flows through the bypass channel, various flow related attributes are sensed by the first sensor (i.e., when the fluid is entering the bypass channel) and by the second sensor (i.e., when the fluid is egressing the bypass channel). The inlet measurement and the outlet measurement generated by the first sensor and the second sensor, respectively may be transmitted to a controller, which may be coupled to the first sensor and the second sensor. The controller may, based on execution of certain programmable instructions, calculate a flow rate of the fluid passing through the primary channel, based on the inlet measurement and the outlet measurement. In an example, the flow rate of the fluid may be based on a difference between the flow attribute values detected at the bypass inlet port and the bypass outlet port.
[0017] As mentioned previously, the flow resistive element may be a
turbine. In such a case, the flow of fluid will impinge on the turbine blades. This in turn causes rotational movement to the shaft. The rotational movement of the turbine further results in the generation of electrical energy. In an example, turbine may be utilized for powering the first sensor and the second sensor. In

another example, the turbine may also be utilized for powering the controller.
[0018] The present approaches provide numerous technical advantages
over previously known flow measuring devices. As would be appreciated that a sensor-based approach for determining the flow rate of the fluid through the primary channel is likely to provide more accurate results when compared to flow rate values which may be determined through mechanical means solely. The flow measuring device as described involves a smaller number of components, and is less complicated as compared to previously known systems. Furthermore, in instances of a turbine (implemented as a flow resistive element) may also be used for powering the different sensors that are provided within the bypass channel. The flow measuring device is thus self-reliant and safe. It may be noted that the above approaches may be performed using a variety of other mechanisms or components. Such examples are further described in conjunction with FIGS. 1-5.
[0019] FIG. 1 illustrates a cross-sectional diagram of a flow measuring
device 100, as per one example of the present subject matter. The flow measuring device 100 may be utilized for determining a flow rate of a fluid which may be passing through an enclosed channel, such as a pipe. The fluid may be a gas or a liquid. Examples of such fluids include, but are not limited to, air, natural gas and liquefied petroleum gas. The flow measuring device 100 may be utilized in industrial, commercial, or residential applications. In an example, the flow measuring device 100 may include an outer casing 102. The outer casing 102 encloses a primary channel 104. In addition to the primary channel 104, the outer casing 102 may further house other components of the flow measuring device 100 (not shown in FIG. 1). In addition, the outer casing 102 may also secure and protect the primary channel 104 and such other components from external conditions, and against tampering. In an example, the primary channel 104 may be a U-shaped pipe.
[0020] Continuing further, the primary channel 104 includes an inlet port
106 and an outlet port 108. The inlet port 106 allows the inflow of the fluid in

the primary channel 104. The fluid is to flow through the primary channel 104, after which the fluid exits the primary channel 104 through the outlet port 108. The inlet port 106 and an outlet port 108 are so adapted such that they may be extending outside the outer casing 102, and couplable to a primary supply of fluid. In an example, the primary channel 104 may lie within the outer casing 102.
[0021] The flow measuring device 100 may further include a bypass
channel 110 which is coupled to, and in fluid communication with the primary channel 104. The bypass channel 110 is so oriented such that it extends parallel to the primary channel 104. The ends of the bypass channel 110, at the point of its coupling with the primary channel 104, defines a bypass inlet port 112 and a bypass outlet port 114. The bypass channel 110, in an example, allows a certain volume of fluid to flow through the bypass channel 110. In an example, the cross-sectional area of the bypass channel 110 is in a specific proportion to the cross-sectional area of the primary channel 104. In an example, the ratio of the cross-sectional area of the bypass channel 110 to the primary channel 104 may be within a range of about 0.1 to about 0.3. In an example, based on the physical attributes of the primary channel 104 and the bypass channel 110, the bypass flow rate may be utilized to estimate the flow rate of the fluid in the primary channel 104.
[0022] The bypass channel 110 is further provided with a first sensor 116
and a second sensor 118. In an example, the first sensor 116 may be positioned in proximity to the bypass inlet port 112. On the other hand, the second sensor 118 may be positioned in proximity to the bypass outlet port 114. The first sensor 116 and the second sensor 118 may be thermal sensor or a pressure. Other types of sensors may be also be included without deviating from the scope of the present subject matter. It is also pertinent to note that although FIG. 1 depicts the first sensor 116 and the second sensor 118 as single sensors, either of the first sensor 116 and the second sensor 118 may be implemented as a combination of multiple sensors without deviating from the scope of the present subject matter.

[0023] The primary channel 104 of the flow measuring device 100 may
further include a flow resistive element 120. The flow resistive element 120, amongst other aspects, is to introduce flow resistances to the flow of the fluid through the primary channel 104. Owing to the flow resistances introduced by the flow resistive element 120, a certain volume of the fluid which may be flowing through the primary channel 104, is to flow through the bypass channel 110. In an example, the flow resistive element 120 may include passive elements such as vanes, or baffles. In another example, the flow resistive element 120 may be a turbine.
[0024] The first sensor 116 and the second sensor 118 may be further
coupled to a flow estimation unit 122. The flow estimation unit 122 may receive sensed signals generated by the first sensor 116 and the second sensor 118, in response to sensing or detecting flow attributes of the fluid flowing through the bypass channel 110. Based on the value of the flow attributes, the flow estimation unit 122 may estimate the flow rate of the fluid which may be passing the primary channel 104. The manner in which the flow rate of the fluid passing through the primary channel 104 is estimated, is further described in conjunction in detail in conjunction with FIG. 2.
[0025] FIG. 2 illustrates an example flow estimation unit 122 for estimating
the flow rate of the fluid which may be flowing through the primary channel 104, within the flow measuring device 100. In an example, the flow estimation unit 122 may include a controller 202, interface(s) 204, memory 206 and data 208. In an example, the controller 202 may be implemented as a combination of hardware or programming, for example, programmable instructions to implement a variety of functionalities of the controller 202. In examples described herein, such combinations of hardware and programming may be implemented in several different ways. For example, when implemented as a hardware, the controller 202 may be a microcontroller, embedded controller, or super I/O-based integrated circuits. The programming for the controller 202 may be executable instructions. Such instructions may be stored on a non-transitory machine-readable storage medium or memory which may be

coupled either directly with the controller 106 or indirectly (for example, through networked means). In an example, the controller 202 may be implementing a processing resource, for example, either a single processor or a combination of multiple processors, to execute such instructions. In the present examples, the non-transitory machine-readable storage medium may store instructions that, when executed by the processing resource, implement controller 202. In other examples, the controller 202 may be implemented as electronic circuitry.
[0026] The interface(s) 208 may include a variety of software and hardware
interfaces that allow the flow estimation unit 122 to interact and receive data or signals from other components, such as the first sensor 116 and the second sensor 118. The memory 206 may include any computer-readable medium known in the art including, for example, volatile memory, such as Static Random-Access Memory (SRAM) and Dynamic Random-Access Memory (DRAM), and/or non-volatile memory, such as Read-Only Memory (ROM), Erasable Programmable ROMs (EPROMs), flash memories, hard disks, optical disks, and magnetic tapes. The data 208 on the other hand, may include data that is generated as a result of the flow sensed by the first sensor 116 and the second sensor 118. In an example, the data 208 includes sensed data 210, flow rate criteria 212 and other data 214.
[0027] In operation, the fluid may be introduced into the primary channel
104 As the fluid flows through the primary channel 104, it will encounter the
flow resistive element 120. In an example, the flow resistive element 120 is to
result in a pressure differences between points which are upstream and the
points which are downstream. Owing to the pressure difference, a certain
volume of the fluid is routed to flow through the bypass channel 110. At this
stage, the fluid enters the bypass inlet port 112. On entering the bypass inlet
port 112, the first sensor 116 is to measure a flow attribute of the fluid flowing
within the bypass channel 110. In an example, the flow attribute may include
temperature or pressure.
[0028] Proceeding further, the fluid continues to flow through the bypass

channel 110 till it reaches the bypass outlet port 114 at which stage, the flow attributes of the fluid may be sensed by the second sensor 118. In response to the flow attributes sensed by the first sensor 116 and the second sensor 118, a sensed signal may be generated. The sensed signal may then be transmitted to the controller 202. The controller 202 on receiving the sensed signals may determine the value of the corresponding flow attribute sensed by the first sensor 116 and the second sensor 118. In an example, the value of the flow attribute may be saved as sensed data 210.
[0029] Once determined, the controller 202 may further determine the
bypass flow rate based on the determined sensed data 210 and based on flow rate criteria 212. In an example, the flow rate criteria 212 may specify one or more physical rules based on which flow rate of the fluid within any channel, such as the bypass channel 110, may be determined. Such physical rules may employ as an input, values pertaining to the different flow attributes (which are stored in sensed data 210). Such values may then be processed by the controller 202 using the flow rate criteria 212.
[0030] As described previously, the cross-sectional dimensions of the
bypass channel 110 are proportional to the cross-sectional dimensions of the
primary channel 104. The controller 202 may then determine the flow rate of
the fluid rate in the primary channel 104, based on the bypass flow rate. In an
example, the value of the flow rate determined by the controller 202 may be
provided to a counter or a display module to track and display the volume or
units of fluid which may have passed through the primary channel 104.
[0031] The foregoing example is further explained in conjunction with FIG.
3, and in the context of the flow attribute being temperature. To such an end, the first sensor 116 and the second sensor 118 may be thermal sensors. In the present example, a thermal source 302 may be provided in the bypass channel 110. The thermal source 302, e.g., a heater, may be positioned in the middle of the bypass channel 110, such that it is downstream with respect to the bypass inlet port 112, and the upstream with respect to the bypass outlet port 114. The thermal source 302 may be activated by the controller 202 when

the fluid is flowing through the bypass channel 110. Owing to the thermal energy provided by the thermal source 302, the temperature of the volume which is downstream the thermal source 302 would be consequently higher than the temperature of the fluid which may be upstream. Consequently, the temperature sensed by the first sensor 116 would be less than the temperature sensed by the second sensor 118.
[0032] The sensed signals are communicated to the controller 202 (as
shown in FIG. 2). Based on the sensed signals, the controller 202 may determine the temperature of the fluid flowing at the bypass inlet port 112 and the bypass outlet port 114. Once determined, the temperatures of the fluid recorded at the bypass inlet port 112 and the bypass outlet port 114, may be stored in sensed data 210. The controller 202 may then utilized the sensed data 210 to determine the flow rate of the fluid flowing through the bypass channel 110. Thereafter, based on the flow rate of the fluid in the bypass channel 110, the controller 202 may determine the flow rate within the primary channel 104.
[0033] In an example, the controller 202 may utilize the following Equation
1 to determine the mass flow:

wherein the mbp is the mass flow from the bypass channel, ‘T1’ is temperature measured by the first sensor 116, ‘T2’ is temperature measured by the second sensor 118, ‘K’ is the meter coefficient which is determined based on certain device attributes, such as dimensions, material properties, etc., ‘Cp’ is the specific heat of the fluid which is flowing through the bypass channel 110, and ‘Q’ is the electric heat rate supplied and maintained by the thermal source 302. In an example, the Equation 1 may be specified in the flow rate criteria 212.
[0034] It may be noted that the above-mentioned example is only
illustrative and is not to be considered as limiting the scope of the present subject matter. It may also be noted that the similar approaches may be

followed for other flow attributes, such pressure. Such approaches and examples would nevertheless fall within the scope of the present subject matter.
[0035] In yet another example, the first sensor 116, the second sensor 118
and the thermal source 302 may be powered from an external power source coupled to the flow measuring device 100. The external power source may be powered through renewable or non-renewable power sources. In an example, the flow resistive element 120 may be a turbine. FIG. 4 depicts another example flow measuring device 400. Similar to the flow measuring device 100, the flow measuring device 400 includes a primary channel 402 and bypass channel 404. The primary channel 402 is further provided with a turbine 406. In an example, the turbine 406 may further include a set of guide vanes 408 and runner vanes 410.
[0036] The turbine 406 may be further coupled to the first sensor 116,
second sensor 118 and the thermal source 302. In operation, as the fluid flows through the primary channel 402, the guide vanes 408 direct the fluid to flow through the turbine 406. The flowing fluid imparts their kinetic energy to the runner vanes 410. The runner vanes 410 rotate as the fluid flows through the turbine. The runner vanes 410 are connected to a shaft which may then rotate in response to the rotation of the runner vanes 410. The rotation of the shaft of the turbine 406 further generates electrical power for powering the first sensor 116, second sensor 118, and the thermal source 302. Thereafter, the controller 202 may determine the flow rate of the fluid passing through the primary channel 402 in a manner similar to the approaches as described in conjunction with the previous figures.
[0037] FIG. 5 provides various perspective views of an example flow
measuring device 500. As illustrated, the flow measuring device 500 may further include a casing or a housing 502. The housing 502 encloses the various components as described in conjunction with the preceding figures. The housing 500 may provide sufficient protection of such internal components against environmental factors, and may also prevent tampering

of the flow measuring device 500.
[0038] Although examples for the present disclosure have been described
in language specific to structural features and/or methods, it is to be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed and explained as examples of the present disclosure.

I/We Claim:
1. A flow measuring device comprising:
a primary channel for transporting fluid having a primary inlet port and a primary outlet port;
a bypass channel coupled to the primary channel, wherein:
a bypass inlet port of the bypass channel is at a point which is upstream with respect to the direction of the fluid flow within the primary channel; and
a bypass outlet port of the bypass channel is at a point which is downstream with respect to the direction of the fluid flow within the primary channel;
a first sensor and a second sensor to measure flow attributes of a portion of fluid flowing through the bypass channel, wherein:
the first sensor is positioned in proximity to the bypass inlet port; and
the second sensor is positioned in proximity to the bypass outlet port;
a controller coupled to the first sensor and the second sensor, wherein the controller is to:
receive a sensed signal from the first sensor and the second sensor, wherein the sensed signal is generated in response to detection of the flow attribute of the fluid flowing through the bypass channel;
based on the sensed signal, determine a flow rate of the fluid flowing through the primary channel.
2. The flow measuring device as claimed in claim 1, further comprising
a flow resistive element, wherein the flow resistive element is to create flow
resistances within the primary channel to cause a portion of the volume of
fluid to be directed through the bypass channel.

3. The flow measuring device as claimed in claim 1, wherein the
controller is to determine the flow rate of the fluid through the primary
channel is to:
determine a value of the flow attribute corresponding to the sensed signal;
based on the determined value of the flow attribute, calculate a bypass flow rate of the fluid flowing through the bypass channel; and
determine the flow rate of the fluid flowing through the primary channel, based on the calculated bypass flow rate.
4. The flow measuring device as claimed in claim 1, wherein the first sensor and the second sensor is a thermal sensor, or a pressure sensor.
5. The flow measuring device as claimed in claim 4, wherein on the first sensor and the second sensor being a thermal sensor, the flow measuring device further comprising a thermal source located in the bypass channel between the first sensor and the second sensor.
6. The flow measuring device as claimed in claim 5, wherein the controller is to further:
receive a sensed signal from the first sensor and the second sensor, corresponding to temperature of the fluid at the bypass inlet port and the bypass outlet port; and
based on the sensed signal, calculate the bypass flow rate of the fluid flowing through the bypass channel.
7. The flow measuring device as claimed in claim 6, wherein the
controller is to determine the bypass flow rate based on the following
equation:


wherein the mbp is the mass flow from the bypass channel,
T1 is temperature measured by the first sensor,
‘T2’ is temperature measured by the second sensor,
‘K’ is the meter coefficient which is determined based on attributes of the
flow measuring device,
‘Cp’ is the specific heat of the fluid flowing through the bypass channel, and
‘Q’ is the electric heat rate supplied and maintained by the thermal source.
8. The flow measuring device as claimed in claim 2, wherein the flow
resistive element is a turbine, and wherein the turbine is to provide electrical
energy to the first sensor and the second sensor.
9. The flow measuring device as claimed in claim 1, wherein the fluid is a liquid or a gas.
10. The flow measuring device as claimed in claim 1, wherein the primary channel is U-shaped.