GB2301457A

GB2301457A - Apparatus for detecting and monitoring fluid flow

Info

Publication number: GB2301457A
Application number: GB9605661A
Authority: GB
Inventors: Gerald John Haines
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-03-21
Filing date: 1996-03-18
Publication date: 1996-12-04
Also published as: GB9605661D0; GB9505713D0

Abstract

In order to accurately monitor the start of a fluid flow from header tank 1 via one way valves 6, 14, in a system of pipes 7-12, and especially in conditions of low head pressure, one or more pressure transducers T 3, 4, 5 are used to monitor the static head pressure drop due to the acceleration of the fluid. This momentary pressure drop can be used to start a pump 2, which increases the pressure in the system. The pressure transducers can be used to monitor the pressures of and pressure differences between the tank and the fluid outlets 7-12 in order to 1) maintain a certain pressure and 2) to stop the pump if there is no fluid flow. In a system comprising one pressure transducer, after the said pump is running, the pressure transducer can be used to monitor the pressure in a closed system and, if the pressure does not fall after a deliberate reduction of pump speed, this information can be used to stop the pump.

Description

APPARATUS FOR MONITORING FLUID FLOW AND ACCELERATION The present invention relates to an apparatus for recording that a fluid has accelerated and for monitoring and measuring fluid flow. Such an apparatus is particularly useful for indicating the commencement of a flow of liquid and determining that a fluid is flowing.

Methods for monitoring and measuring fluid flow are well known. Such methods include differential pressure measurement and in-line flowmeters of many types. In static conditions where no fluid is flowing it is customary to detect the commencement of a flow of fluid by using methods such as a flowmeter.

However in conditions of low head pressures and/or low flow rates expensive flowmeters need to be used in order to detect the commencement of low fluid flow rates. If it is only required to detect if a fluid is flowing without the necessity to measure the actual flow a flowmeter is expensive when compared to other types of transducer.

The present invention will now be described with reference to the accompanying drawing.

Refening to the drawing, there is provided three pressure transducers numbered (3), (4) and (5): number (3) transducer is located after a non-retum valve (14), water pump (2), water tank (1) and non-retum valve (6); numbers (4) and (5) transducers are preferably located after the main distribution pipe (13) and at the final distribution pipes (7) and (12) respectively in a system of distribution pipes numbered (7) to (12) in the drawing. The distribution pipes (7) to (12) have water flowing or not flowing through them depending upon system requirements downstream of the distribution pipes. All of the components of the system are located below the water tank (1).

Means are provided to measure the outputs of the transducers ("Measuring Means"): preferably the said means is a data processor. In the initial state the water pump (2) is not running. In the condition of zero flow all transducer outputs will be substantially the same and will give an output proportional to the head pressure of the water tank (1); however when a flow of fluid commences from the water tank (1) in the direction of transducers (4) andlor (5) there will be a pressure difference between transducers (4) and/or (5) and transducer (3).Under conditions of low head pressure and low flow rates this difference will be extremely small and very difficult to measure; however, in addition to the normal (small) pressure drop between the transducers, there also exists a drop in static head ("piezometric head") pressure in the pipe system due to the acceleration of the fluid from a condition of zero flow rate: with the present invention "Measuring Means" are used to monitor this drop in pressure ("pressure dip"), preferably from any one of, or any combination of, transducers (3), (4) and (5), and means ("Controlling Means") are provided to use this information to start the water pump (2): preferably this means is a data processor.

Water pressure is then increased and monitoring of water flow is made relatively easy by using "Measuring Means" to measure the pressure difference between transducers (4) and (3) and transducers (5) and (3) respectively: a minimum pressure is maintained at transducers (4) and (5) by varying the speed of the water pump (2) using the "Controlling Means". According to one aspect of the present invention, when there is no water flow (ie where there is no pressure difference between transducer (3) and either of transducers (4) and (5)), "Controlling Means" will cycle water pump (2) off.According to another aspect of the present invention, the pressure at any one of the transducers (3), (4) or (5) can be monitored using "Measuring Means" and, while the speed of the said pump is deliberately reduced by a pre-determined amount using "Controlling beans", the "Measuring Means" can detect if there is a fall in pressure ("Fall in Pressure Method ): this would signify a flow of water through any of distribution pipes (7) to (12) because the system is essentially a closed system due to the presence of non-retum valve (14): if there is no fall in pressure then "Controlling Means" is used to cycle water pump (2) off. If water pump (2) does not cycle off after a pre-determined period of time then an indication of a leak in the system can be alarmed.Using the "Fall in Pressure Method" any two of transducers (3), (4) or (5) can be omitted and the remaining transducer positioned anywhere after the non-retum valve (14).

After water pump (2) has cycled off, monitoring of the pressure by "Measuring Means" continues: any drop of pressure will cause "Controlling Means" to cycle the water pump (2) on. If, however, due to small system leaks, the pressure falls to water tank (1) head pressure then water pump (2) will cycle on using the "pressure dip" method explained above.

Using this system water pump (2) is running at its optimum speed for system pressure required and is only running when there is a demand for water thus saving energy as compared to cases where water pump (2) is running continuously. In applications where water pump (2) is only run during certain "peak" periods, this present system improves the supply of water by being "on-line" at all times of water flow even during periods of low flow rates and also where said low flow rates are for a short period of time.

Although reference here is made to water, the description is equally applicable to other fluids.

Claims

1. An apparatus used in a piping system for recording that a fluid has accelerated using the principle of static head ("piezometric head") pressure drop during periods of fluid acceleration.

Means are provided to monitor static head pressure drops. The said apparatus comprises one or more pressure transducers located in the piping system and a data processor to monitor the outputs of the transducers.

2. An apparatus as claimed in Claim 1 where the piping system comprises a header tank and pump in series and, from an initial state of zero fluid flow, any start of fluid flow causes said static head pressure drop and information thus obtained from the data processor is used to start said pump in order to increase the fluid pressure.

3. An apparatus as claimed in Claim 2 where pressure transducers are located in the piping system in such positions as to enable the information thus obtained from the transducers to measure system flow rates and pressure and also to control the speed of said pump in order to maintain a certain pressure.

4. An apparatus as claimed in Claim 3 where the information conceming flow rate is used to stop the said pump when there is zero fluid flow.

5. An apparatus as claimed in Claim 2 where one pressure transducer is located in the piping system in such a position as to enable the information thus obtained from the transducer to measure a fall in pressure when the pump speed is reduced and this information used to stop the said pump if there is no fall in pressure.

6. An apparatus substantially as described herein with reference to the accompanying drawing.

Amendments to the claims have been filed as follows 1. An apparatus used in a closed piping system of fluid comprising a fluid head, pump, one or more pressure transducers, Monitoring and Controlling Means, and a speed controller, which are used in conjunction to control pump running cycles and system pressure and where, when the pump speed is reduced by Controlling Means, the pump will stop if there is a negligible fall in system pressure recorded by Monitoring Means.

2. An apparatus as described in Claim 1 where, when the pump speed is reduced by Controlling Means, the pump will stop if there is a predetermined fall in system pressure recorded by Monitoring Means.

3. An apparatus as described in Claim 1 where the Monitoring and Controlling Means is a data processor.

4. An apparatus as described in Claim 1 where there are multiple pumps connected in parallel.

5. An apparatus as described in Claim 3 where there are multiple speed controllers.

6. An apparatus as described in Claim 1 where, if the pump does not stop for a predetermined period, then an alarm will be given indicating that there is a leak in the system.

7. An apparatus substantially as described herein with reference to the accompanying drawing.