1、PUBLISHED DOCUMENTPD CR 13582:1999Heat meter installation Some guidelines for selecting, installation and operation of heat metersICS 17.200.10g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37
2、g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58PD CR 13582:1999This Published Document was published under the authority of the Standards Policy and Strategy Committee on 31 March 2008 BSI 2008ISBN 978 0 580 61695 2National forewordThis published document is the UK implementation of CR 13582:1999.The UK
3、 participation in its preparation was entrusted by Technical Committee CPI/30, Measurement of fluid flow in closed conduits, to Subcommittee CPI/30/7, Volume flow-rate methods. A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not
4、 purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Amendments/corrigenda issued since publicationDate CommentsCEN REPORTRAPPORT CENCEN BERICHTCR 13582July 1999English versionHeat meter installation - Some guidelines for selecting,install
5、ation and operation of heat metersThis CEN Report was approved by CEN on 24 March 1999. It has been drawn up by the Technical Committee CEN/TC 176.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Lux
6、embourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGCentral Secretariat: rue de Stassart, 36 B-1050 Brussels 1999 CEN All rights of exploitation in any form and by any
7、means reservedworldwide for CEN national Members.Ref. No. CR 13582:1999 EICS 17.200.10CONTENTS1 INTRODUCTION 31.1 GENERAL .31.2 EXPLANATIONS OF TERMS.32 SELECTION OF METERS .32.1 GENERAL 32.2 OPERATIONAL CONDITIONS42.3 LIFE CYCLE COSTS 52.4 FLOW SENSORS.52.4.1 General52.4.2 Quality of the heat conve
8、ying liquid 62.4.3 Measuring principles / type of sensors .6a) Turbine flow sensor 6b) Magnetic inductive flow sensor.7c) Ultrasonic flow sensor 8d) Fluidistor flow sensor9e) Other types of flow sensors92.4.4 Sizes and dimensions.92.5 TEMPERATURE SENSORS.102.5.1 Temperature probes - general.102.5.2
9、Using temperature pockets112.5.3 Surface mounted temperature sensors. 112.6 CALCULATORS12Heat calculation. .123 LOCATING THE METERS .133.1. ENVIRONMENT .133.1.1 Electromagnetic interference133.1.2 Thunderstorm / Surge transients133.1.4 Temperature and humidity133.2 FLOW SENSORS133.2.1 Flow profile 1
10、33.3 TEMPERATURE SENSORS.163.3.1 General163.3.2 Locating temperature probes173.4 CALCULATORS174 INSTALLATION OF THE METERS174.1 GENERAL .174.2 MECHANICAL .184.4 ELECTRICAL CONNECTION 184.5 TAKING INTO SERVICE 185 OPERATIONAL MONITORING196 REFERENCES .19ANNEX A: QUALITY OF THE HEAT CONVEYING LIQUID .
11、20A1 GENERAL.20A2. LIQUID QUALITY .20A3. QUALITY OF THE HEAT CONVEYING LIQUID .20ANNEX B: THE EFFECTS OF INFLUENCE QUANTITIES ON THE MEASUREMENT ACCURACY OFDIFFERENT TYPES OF FLOW SENSORS24ANNEX C: FLOW SENSOR VARIETY 27Page 2PD CR 13582:19991 Introduction1.1 GeneralWhen EN1434 was being prepared, m
12、uch useful information and practical advice concerning the choiceand installation of heat meters was received. Though unsuitable for inclusion in the standard it is givenhere to help heat meter users.1.2 Explanations of termsFor the purposes of this report, in addition to the definitions in EN1434,
13、the following terms and symbolsapply1.2.1 DH (network)District heating systems1.2.2 MeterHeat (energy) meter1.2.3 WaterSanitary water1.2.4 Warm waterSanitary warm water1.2.5 Make up liquidLiquid for refilling leakage of heat conveying liquid1.2.6 LiquidHeat conveying liquid in a DH system2 Selection
14、 of meters2.1 GeneralA heat meter is composed of three parts, a flow sensor, a temperature sensor pair and a calculator.The calculator is a unit which calculates volumes and energy consumption using the values from thetemperature sensors and the flow sensor.The most common type of temperature sensor
15、 is a resistance thermometer of platinum type Pt 100, Pt500 or Pt 1000. The sensors measure the temperature difference between the incoming and outgoingliquid .The flow sensor is probably the most troublesome assembly of the heat meter. Despite an accuracyrequirement of only 4-10% it is very easy to
16、 fall outside these limits. In order to counter these effects asfar as possible, there follows a summary of the various types of flow sensor and their advantages anddisadvantages.The sizing of meters to match their required duty frequently turns out to have been incorrectly estimatedwhen the heating
17、 plant commences operation. In most cases heat meters that are too large for theirPage 3PD CR 13582:1999eventual duty are specified and accuracy at low load suffers as a result. Whilst this paper will give someguidance on essentials, it is felt that more information on this topic would be welcomed.H
18、eat meter accuracies at times of rapidly changing heat demand are unlikely to be high. Whilst at timesof low demand the effect of meter inaccuracy in terms of lost revenue is likely to be small, rapid changesinvolving high demands on the network may possibly have important implications in lost reven
19、ue if meterreaction to rapid changes is slow. Research into the subject seems to have been largely neglected sofar.The most commonly used types of flow sensors have been listed in Annex B and the effect on accuracyof different types of disturbances for each of the listed types of flow sensors are co
20、nsidered.There is little information on the effects of flow and flow disturbances on the service life of the flowsensor, as distinct from its effect on the sensors accuracy. To be welcomed, therefore, is the long termresearch project on this topic initiated in Germany which should result in useful d
21、ata.2.2 Operational conditionsTo get the total power needs of the building you have to calculate the sanitary warm waterproduction and add this power to the power due to heating.The demand of power for sanitary warm water may be calculated by using the ”Guidelines for hotservice water preparation” w
22、hich is the established European method worked out by Euroheat andPower (UNICHAL).When the maximum power is found the sizing of the meter can start.Effect on accuracy of changes in heat demandIn times of changing heat demand, factors which have an important effect on measurement resultsare:Level of
23、system temperaturesOperating strategies of the networkThe quality of the installationHow the substations are designedThe changing temperature level in the buildingThe maintenance levels of the buildingTherefore it is essential to have a routine or checklist for the personnel dealing with meters in t
24、heDH-company. The routine should cover consideration of all factors above.A classic expression is to measure is to know, and there is a great deal in this. But severalpreconditions should be met to enable the measured values to be used and understood in the right way:You must know what you want to m
25、easure and use the correct measuring method for thatpurpose.You must have data on the object being measured.That the most suitable meter is used for what is to be measured.That the limits of the meters are known.Page 4PD CR 13582:19992.3 Life cycle costsOnce you have established the technical requir
26、ements for the meters you have to buy them fromsomewhere. The tenders from different suppliers should be evaluated. Then you should consider notonly the cost price but also the costs for:installationservice and maintenancespare partstesting and verificationstoragereplacement metersexpected service l
27、ife (in years)expected intervals for overhaul (in years)trouble shootinglost revenues due to poor accuracylost revenues due to faults and standstillsOf course many of the listed costs are difficult to estimate, especially when it comes to new types ofmeters or new manufacturers, but with the experie
28、nce from other similar meters, technical knowledgeand common sense you should reach a satisfactory estimate.It is a recommended not to buy too many meters at the same time when you are not familiar with thetype of meter or the manufacturer. The meter is perhaps not suitable for the quality of your h
29、eatconveying liquid, the procedures for testing the meter are maybe costly or even impossible at yourordinary testing facilities and so on.2.4 Flow sensors2.4.1 GeneralIn order to optimise the conditions for a flow sensor, the following recommendations should be followedas far as possible, irrespect
30、ive of which type of sensor is being used.Long straight pipesA straight pipe cannot be too long, which is why it is best to take advantage of all physical opportunitiesfor straight pipes. If the measurement position is planned at the design stage, this usually makes itpossible to take advantage of s
31、traight pipes.Avoid rotating flowRotating flow is always a bad thing, and should be avoided, for example, by fitting pipes correctly. If thepipe run cannot be altered, a flow conditioner is a possible solution, but be careful of increased pressuredrop.Avoid pulsating flowThis is avoided by correct p
32、ositioning of the sensor in relation to pumps or other sources of pulses.Correct sensor sizeWhat is the actual nominal flow, and how often is maximum flow reached?Page 5PD CR 13582:1999Calibration in the right environmentIdeally a sensor should be tested under conditions as close to its actual worki
33、ng environment aspossible. This means that the sensor should be tested at the correct temperature and with a liquid qualitywhich closely corresponds to the actual liquid in the system.The correct type of sensor in relation to the liquid quality.Which type of sensor suits your quality of liquid the b
34、est?2.4.2 Quality of the heat conveying liquidIt is widely recognised that liquid quality has an important effect on the service life and operation of liquidheating systems through the interaction between the liquid and construction materials of the system, butlittle guidance is available concerning
35、 the effect of liquid on the durability etc. of heat meters. Even onwhat might be thought to be a relatively simple matter on which to have agreement, i.e. the pH of theliquid, there is conflicting advice. In the UK 6.5 to 8.5 pH is recommended whereas in Sweden 4000 and the liquid is homogenous, th
36、eflow is always turbulent.Figure 9 - Laminar flow Figure 10 - Turbulent flowPage 13PD CR 13582:1999Figure 11 - Asymmetrical flow Figure 12 - Swirling flowThe flow profile at the measurement position has a very considerable influence on all types of flowsensors. Those sensors which only measure at a
37、single measurement point, e.g. single-jet ultrasoundsensors, are very dependant on the flow pattern within the measurement area being representative ofthe whole area of flow. Different sources of disturbance affect the flow pattern in many different waysand the distance between the sensor and the so
38、urce of disturbance is highly significant.Asymmetrical flowAn asymmetrical flow pattern may be caused by a bend in a pipe, a valve, a filter or badly fitted insertionjoint. The inner surface of the pipe is very important in determining how quickly the disturbance diesdown and the flow becomes symmet
39、rical again. A long straight pipe is always satisfactory.Swirling flowA swirling flow pattern arises where there are two bends near each other in the pipe in two differentplanes. This is a particularly unwelcome form of disturbance, and can, in extreme cases with certaintypes of sensors, show a reve
40、rsed flow. The solution is to avoid as far as possible these types of pipebends. If this is not possible a long straight pipe is required and in difficult cases a flow director should beused.Pulsating flowThe cause of pulsating flow is most often a pump, which is why a measurement pipe should be pla
41、ced asfar from the pump as possible and never on the suction side.Page 14PD CR 13582:1999Figure 13 - Suitable and unsuitable flow sensor positionsA Suitable position for most types of sensors.B This position should not be used for certain types of mechanical sensors.C This is an unsuitable sensor po
42、sition since air-pockets can be formed.D This is an unsuitable sensor position since air-pockets can be formed.E A sensor should not be placed immediately after a valve.F A sensor should not be placed at the suction side of a pumpG A sensor should not be placed downstream a double bend in two planes
43、.Page 15PD CR 13582:19993.3 Temperature sensors3.3.1 GeneralThe necessary accuracy in temperature measurement can only be achieved if the greatest care is takenby well trained competent personnel in the installation of the temperature probes of the heat meter.Different temperature levels in the meas
44、urement area (Figure 14) or zones with no flow (Figure15) are tobe avoided. Standing liquid cools and only part of the heat reaches the measurement resistance. Themeasured heating liquid temperature is then reducedFigure 14 - Different temperature levels in the measurement areaFigure 15a - Tip of se
45、nsor in Figure 15b - Tip of sensor not deeplyzone of silence enough immersedWith a temperature difference between heating liquid/temperature probe and the pipe, heat is conductedto the outside via the connection to the pipe.This risk is especially evident with short probes. The temperature at the me
46、asuring resistance is therebylowered and the measurement is falsified. With longer temperature probes the spacing between theconnector and the measuring resistance is longer. They are therefore deeper in the heating liquid flowand the heat loss via the connector cannot influence the measurement of t
47、he temperature so strongly.Page 16PD CR 13582:1999With short temperature probes, the signal cable between probe and calculator is often directlyconnected to the measuring resistance. If the installed probe is inadequately thermally insulated, heatcan be lost to the outside via the signal cable . Thi
48、s results in a temperature reduction at themeasurement resistance3.3.2 Locating temperature probesFor heat transfer from the heating liquid to the temperature probe tube, the position of the measuringresistance in the pipe cross section and above all the flow rate, is decisive. The higher the flow r
49、ate thebetter is the heat transfer from the heating liquid to the temperature probe. In constructing theconnection of the temperature probe, care should be taken that an adequate flow rate prevails at themeasuring point and that the measuring resistance is installed so that it lies at the centre of the crosssection if possible (Figures 16 and 17). The restriction of the pipe cross section caused by theinstallation of the probe generates an increase in the flow velocity at this point, thus exerting a positiveeffect on the heat measurement.Figure 16 - Probe installation in a
