GB2275115A - Commissioning of fluid flow systems - Google Patents

Commissioning of fluid flow systems Download PDF

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Publication number
GB2275115A
GB2275115A GB9302781A GB9302781A GB2275115A GB 2275115 A GB2275115 A GB 2275115A GB 9302781 A GB9302781 A GB 9302781A GB 9302781 A GB9302781 A GB 9302781A GB 2275115 A GB2275115 A GB 2275115A
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GB
United Kingdom
Prior art keywords
flow
branch
terminal
flow rate
dfr
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9302781A
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GB9302781D0 (en
GB2275115B (en
Inventor
Anthony Richard Case
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Individual
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Individual
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Publication date
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Priority to GB9302781A priority Critical patent/GB2275115B/en
Publication of GB9302781D0 publication Critical patent/GB9302781D0/en
Publication of GB2275115A publication Critical patent/GB2275115A/en
Application granted granted Critical
Publication of GB2275115B publication Critical patent/GB2275115B/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D7/00—Control of flow
    • G05D7/06—Control of flow characterised by the use of electric means
    • G05D7/0617—Control of flow characterised by the use of electric means specially adapted for fluid materials
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/70—Control systems characterised by their outputs; Constructional details thereof
    • F24F11/72—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure
    • F24F11/74—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure for controlling air flow rate or air velocity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
    • G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
    • G01F1/36—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure the pressure or differential pressure being created by the use of flow constriction
    • G01F1/40—Details of construction of the flow constriction devices
    • G01F1/46—Pitot tubes

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Measuring Volume Flow (AREA)

Abstract

In commissioning a closed or open fluid flow system by adjusting actual flow rates at different locations to achieve the corresponding design flow rates, a flowmeter 3 is located at the 'least flavoured' terminal 2 of the system and its reading is transmitted to a second terminal 5 where the flow is being adjusted by a regulator 6 with the help of a second flowmeter. The readings from both flowmeters are displayed on a single unit 4 so that the results on both flow rates as regulator 6 is adjusted may be observed. When regulator 6 has been optimised, the second flowmeter and unit 4 are moved to another terminal and the process repeated. The readings may be in terms of velocity or flow rate or flow rate as a percentage of design flow rate. The transmission is by radio or through an electric or fibre optic cable. <IMAGE>

Description

A DEVICE FOR THE PARTIAL AUTOMATION OF THE COMMISSIONIN6 OF FLUID FLOW SYSTEMS Technical field The object of commissioning fluid flow systems is to ensure that the installations operate in conformity with the requirements of the design specification. This specification will give the required flow rates in each section of the system. In a closed system the fluid may transfer heat or in an open system simply transfer the fluid.
Background of the Invention A closed system will usually have a number of circuits, with each circuit having a specified flow rate and a method of measuring and adjusting the flow rate. It is therefore necessary to adjust the flow rate in each circuit so that the design specification can be achieved. The most suitable and recognised way to achieve this is proportional balancing.
The method employed is to locate the main conduits and list them, in order, starting with the conduit with the highest percentage design flow rate DFR (%) = 100fa/fd, where fa is the actual flow rate and fd is the design flow rate.
The circuit branches from these main conduits are then listed in descending order of DFR (%). The branch with the highest DFR (%) will be the most favoured circuit.
Starting with the least favoured terminal on the most favoured circuit the DFR (S) is recorded and the next terminal nearer the pump or circulating device is adjusted so that the DFR (%) for this terminal and the least favoured terminal are equal within the specified tolerance.
The terminal next nearer the circulating device is adjusted so the DFR (S) for this terminal and the least favoured terminal on this branch are equal within the specified tolerance.
It should be noted that the DFR (%) of the least favoured terminal will change each time the flow rate is adjusted in any other terminal and repeated measurements will need to be taken to ensure proportional balance to within the specified tolerance.
When all the terminals on this branch are regulated in a similar manner then each terminal will be in balance with every other terminal on that particular branch.
The terminal balancing is repeated on the next most favoured branch and this sequence is repeated until all the terminals on this main conduit are balanced.
The flow rate through the branches on this main conduit are now adjusted following the same procedure as for each terminal.
This method is repeated for each main conduit until all the terminals, branches and main conduits have been treated.
If several main conduits are fed from the same header the same procedure should be used to balance these main conduits.
At this stage every terminal branch and main conduit are proportionally balanced within the specified tolerance.
The flow rate through the circulating device can now be regulated to bring the total flow to design flow. The required flow within the specified tolerance at each terminal branch and main conduit should now be circulat ing.
An air distribution system for the ventilation of a building can be described as an open system It will incorporate two systems, one to supply the air to the room, the other to extract the air.
The flow rate in main conduits and branches of air systems are usually measured with a pitot-static tube connected to a manometer, with the manometer giving the point velocity pressure which is converted to the point velocity using the air density. The pitot-static tube is inserted into the conduit through a hole with its inlet pointing towards the air flow. The point velocity is recorded for various points in a grid, with the grid conforming to certain geometry depending on the size and shape of the conduit. The arithmetic mean of these readings is calculated, with the volume flow given by the mean velocity multiplied by the area of the conduit.
A vane anemometer can be used, or the like, mounted in the outlet to a hood, to measure the volume flow from a terminal. The hood will be designed to keep the outlet velocity as low as possible consistent with obtaining uniform flow through the outlet. When DFR (S) of terminals of similar size, type and flow rate are compared the resistance factor of the hood is self cancelling.
If the DFR (%) is compared on terminals of different size, flow rate, or outlet velocity the hood resistance factor is not self cancelling. Hood factors must be derived. Air flow is measured at a suitable terminal using an appropriate hood for various flow rates. The air flow is measured in the conduit feeding the terminal for similar flow rates using a pitot-static tube. A relationship for the flow rate measured by the pitot-static tube, and the flow rate measured using the hood can be established.
The indicated flow rate given by the hood measurement can be expressed as an equivalent pitot-static tube flow rate.
If the resistance factor of hoods is not self cancelling then this equivalent pitot-static tube flow rate should be used in calculating the DFR (S).
Thus it is necessary to compare the DFR (%) of the terminal, branch, or main conduit to the DFR (%) of the least favoured terminal, branch, or main conduit in that particular section of the system. The flow rate of the terminal, branch or main conduit is adjusted until its DFR is is approximately equal (within the specified tolerance) to the DFR (%) of the least favoured terminal, branch, or main conduit in that particular section of the system to obtain proportional balance. This will need to be carried out on a trial and error bases as DFR (%) of the least favoured terminal, branch or main conduit will change with each flow rate adjustment.
Brief summary of the invention It is the object of the invention to reduce the time required to commission fluid flow systems and improve the accuracy of flow regulation. A good deal of time, in commissioning a fluid flow system, is spent on trial and error flow rate adjustments to obtain proportional balance. The accuracy of this balance has been known to suffer.
It is proposed that two flow monitoring devices are used to obtain proportional balance in each section of the system. One unit will be positioned at the least favoured terminal, branch or main conduit, the other at the terminal, branch or main conduit being adjusted. The unit at the least favoured position will send a signal to the unit where the flow adjustment is being made. This signal will contain flow rate information and allow the two DFR (%) or flow rates to be compared, so flow adjustment can be made, and proportional balance to obtained. The unit positioned at the flow adjustment point will be moved to the next terminal, branch or main conduit and the procedure repeated. Thus the whole system may be brought to proportional balance with reduced time, labour and greater accuracy.
DescriPtion of the Drawings Figure 1 shows the Invention being used to proportionally balance two terminals in an open fluid flow system, which is described in the first form of the Invention below.
Figure 2 shows the Invention being used to proportionally balance two branches of an open fluid flow system.
Figure 3 shows the Invention being used to proportionally balance two terminals in a closed fluid flow system.
A Description of the first form of the Invention The unit 1, positioned at the least favoured terminal 2, as shown in figure 1, contains a microprocessor, an alphanumeric display, data entry keyboard, RF transmitter and is connected to a vane anemometer 3. The vane anemometer, thermal anemometer or similar device can be mounted in a hood which is positioned over the terminal or in a position adjacent to the terminal as shown. The unit 4, at the terminal adjustment point is similar but the transmitter is replaced by an RF receiver. The transmitting unit 1, is programmed with the design flow, and either the hood outlet area, dimensions or diameter, via the alpha-numeric keyboard.The transmitting unit 1 is then capable of displaying the velocity as recorded by the vane anemometer, the measured flow rate or DFR (S). The receiving unit 4, is similar to unit 1, but can also display the DFR (S), velocity or flow rate as transmitted by the other unit 1.
Thus the flow rate at the terminal being monitored by the receiving unit, can be adjusted using a flow regulating device 6, until the DFR (%), flow rate or velocity of the least favoured terminal is approximately equal to the DFR (%), flow rate or velocity of the terminal being adjusted by consulting the receiving unit's alpha-numeric display.
The description of the second form of the Invention The transmitter unit 1, and receiver unit 4, as shown in figure 2 will be essentially the same as the units described in the first form of the Invention but the units will have the facility for measuring the velocity of a fluid flowing using a pitot-static tube 7, or similar device. This will enable the units to measure flow in branches or main conduits.
The pitot-static tube or similar device of the transmitting unit 1, will be positioned to give a true representation of the velocity and may need a coefficient to operate on the value to make it represent a true average velocity.
The receiving unit 4, may have the added facility to take point readings from the pitot-static tube traverse and give the average velocity and calculate the DFR (%).
The descriDtion of the third form of the Invention The transmitter unit 1, and receiver unit 4, as shown in figure 3 will be essentially the same as the units described in the first form of the Invention but the units will have the facility for measuring the flow through closed fluid flow systems using either an orifice plate 8, venturi, orifice valve, variable orifice valve, ultrasonic flow meter, turbo flow meter or similar device. Thus the transmitted DFR (%) or flow rate may be compared to the DFR (S) or flow rate at the receiving unit 4, and appropriate flow adjustments made using a flow regulation valve 9, or similar device to bring the terminal 10, branch 11 or main conduit 12, into proportional balance with the terminal, branch or main conduit at the transmitting unit 1, which in this case is positioned at the least favoured terminal.

Claims (6)

1. A device which will receive data from a flow measuring unit and convert this data into a signal which will be suitable for transmission to a receiving device. The device will then transmit the signal. A device will use this transmitted signal and compare it, or make it suitable for comparison by the commissioning engineer, to the flow data coming from the flow measuring unit at the terminal, branch, sub-branch or main conduit, where the flow is being regulated, so to obtain proportional balance in flow rate.
2. A transmitting and receiving device as in claim 1, in which the flow data communication signal is transmitted using radio waves.
3. A transmitting and receiving device as in claim 1, in which the flow data communication signal is transmitted along an electrical conductor or conductors.
4. A transmitting and receiving device as in claim 1, in which the flow data communication signal is transmitted along a fibre optic cable.
5. A transmitting and receiving device as in claim 1, in which the flow data communication signal is transmitted using part of the electromagnetic spectrum.
6. A transmitting and receiving device as in claim 2, 3, 4, or 5, where the flow data communication signal is used to automatically adjust the flow rate being monitored at the receiving unit so as to obtain proportional balance in flow rate.
Amendments to the claims have been filed as follows 1. A device which will be constructed using a microprocessor and/or solid state circuitry and will contain an alpha-numeric display, data entry keyboard, signal conditioning circuitry, and data transmitter.
This device will take signals from a flow sensor stationed at the least favoured terminal, branch, or sub branch in a fluid flow system and convert them into a suitable format for display on the alpha-numeric display in engineering units. This data will be transmitted to a similar device containing a data receiver.
The data receiver unit will be positioned at the terminal, branch or sub branch where the flow rate is being adjusted by the commissioning engineer to obtain proportional balance of flow in the system.
This device will display the DFR (st;) being received from the least favoured terminal, branch or sub branch, and the DFR % of the terminal, branch or sub branch being adjusted using a suitable fluid flow adjustment damper, valve or the like. (The DFR (%) is defined as the actual flow rate divided by the design flow rate and given as a percentage.) The commissioning engineer will adjust the flow until the received DFR (%) and the DFR (%) at the terminal, branch, or sub branch being adjusted are the same within a suitable margin.
Thus the commissioning engineer will bring the system into proportional balance by repeating the procedure at every terminal, branch or sub branch on the system.
GB9302781A 1993-02-12 1993-02-12 A device for the partial automation of the commissioning of fluid flow systems Expired - Lifetime GB2275115B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9302781A GB2275115B (en) 1993-02-12 1993-02-12 A device for the partial automation of the commissioning of fluid flow systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9302781A GB2275115B (en) 1993-02-12 1993-02-12 A device for the partial automation of the commissioning of fluid flow systems

Publications (3)

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GB9302781D0 GB9302781D0 (en) 1993-03-31
GB2275115A true GB2275115A (en) 1994-08-17
GB2275115B GB2275115B (en) 1996-01-10

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE29709029U1 (en) * 1997-05-22 1997-07-17 Werner, Beat E., Kloten Heat meter
EP0697582A3 (en) * 1994-07-22 1998-07-01 BG plc Apparatus for measuring the flow rate of a fluid
WO2000031602A1 (en) * 1998-11-20 2000-06-02 Sepiatec Gmbh Method and device for regulating individual sub-flows of a system for conveying fluid media
WO2003001312A1 (en) * 2001-06-21 2003-01-03 Abb Oy Method and apparatus for controlling systems distributing flowing medium
GB2516613A (en) * 2013-05-23 2015-02-04 Nuaire Ltd An in-situ method of airflow measurement for fans and ventilation systems
CN105284633A (en) * 2015-11-23 2016-02-03 嘉兴职业技术学院 Air supply system for livestock breeding
WO2017111896A1 (en) * 2015-12-21 2017-06-29 Dwyer Instruments, Inc. System, method, and apparatus for balancing an hvac system
US10671098B2 (en) 2015-12-21 2020-06-02 Dwyer Instruments, Inc. System, method, and apparatus for balancing an HVAC system
SE2151365A1 (en) * 2021-11-08 2023-05-09 Devair Ab Method and arrangement for balancing a gas flow system

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0219215A2 (en) * 1985-08-30 1987-04-22 J.E. MATHER &amp; SONS LTD. Flow monitoring system
GB2231668A (en) * 1989-05-16 1990-11-21 Compania Para La Fabricacion D Remote reading and cutoff system for domestic gas meters

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0219215A2 (en) * 1985-08-30 1987-04-22 J.E. MATHER &amp; SONS LTD. Flow monitoring system
GB2231668A (en) * 1989-05-16 1990-11-21 Compania Para La Fabricacion D Remote reading and cutoff system for domestic gas meters

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0697582A3 (en) * 1994-07-22 1998-07-01 BG plc Apparatus for measuring the flow rate of a fluid
DE29709029U1 (en) * 1997-05-22 1997-07-17 Werner, Beat E., Kloten Heat meter
WO2000031602A1 (en) * 1998-11-20 2000-06-02 Sepiatec Gmbh Method and device for regulating individual sub-flows of a system for conveying fluid media
US6532978B1 (en) * 1998-11-20 2003-03-18 Sepiatec Gmbh Method and device for regulating individual sub-flows of a system for conveying fluid media
WO2003001312A1 (en) * 2001-06-21 2003-01-03 Abb Oy Method and apparatus for controlling systems distributing flowing medium
GB2516613A (en) * 2013-05-23 2015-02-04 Nuaire Ltd An in-situ method of airflow measurement for fans and ventilation systems
CN105284633A (en) * 2015-11-23 2016-02-03 嘉兴职业技术学院 Air supply system for livestock breeding
CN105284633B (en) * 2015-11-23 2018-02-02 嘉兴职业技术学院 A kind of supply air system of livestock-raising
WO2017111896A1 (en) * 2015-12-21 2017-06-29 Dwyer Instruments, Inc. System, method, and apparatus for balancing an hvac system
CN108885472A (en) * 2015-12-21 2018-11-23 德怀尔仪器公司 System for balancing HVAC system, method and apparatus
US10671098B2 (en) 2015-12-21 2020-06-02 Dwyer Instruments, Inc. System, method, and apparatus for balancing an HVAC system
SE2151365A1 (en) * 2021-11-08 2023-05-09 Devair Ab Method and arrangement for balancing a gas flow system

Also Published As

Publication number Publication date
GB9302781D0 (en) 1993-03-31
GB2275115B (en) 1996-01-10

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Legal Events

Date Code Title Description
727 Application made for amendment of specification (sect. 27/1977)
727J Application withdrawn (sect. 27/1977) [amendment after grant]
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20070212