1、BRITISH STANDARD BS 4954-1: 1973 Methods for Testing and rating induction units for air distribution systems Part 1: Thermal and aerodynamic performance UDC 697.953.001.42+697.953.001.42:536.6+533.6.08BS4954-1:1973 This British Standard, having been approved by the Refrigeration, Heating and AirCond
2、itioning Industry Standards Committee, was published under the authority ofthe Executive Board on 5October 1973 BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference RHE/6 Draft for comment 71/36147 ISBN 0 580 07545 1 Co-operating organizations The Refrige
3、ration, Heating and Air Conditioning Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Association of Consulting Engineers* Association of Manufa
4、cturers of Domestic Electrical Appliances Boiler and Radiator Manufacturers Association* British Gas Corporation British Mechanical Engineering Confederation British Oil and Gas Firing Equipment Manufacturers Association British Refrigeration and Air Conditioning Association* Department of the Envir
5、onment Department of Health and Social Security* Electricity Council, The Central Electricity Generating Board and the Area Boards in EnglandandWales Engineering Equipment Users Association Heating and Ventilating Contractors Association* Heating and Ventilating Research Association* HEVAC Associati
6、on* Institute of Fuel Institute of Refrigeration* Institution of Electrical Engineers Institution of Gas Engineers Institution of Heating and Ventilating Engineers* Lloyds Register of Shipping Ministry of Defence, Navy Department* National Coal Board Royal Institute of British Architects Society of
7、British Gas Industries Water-tube Boilermakers Association The Government departments and scientific and industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard
8、: Department of the Environment, Building Research Establishment Greater London Council Oil Appliance Manufacturers Association Steel Radiator and Convector Manufacturers Association Unit Heater Manufacturers Association Amendments issued since publication Amd. No. Date of issue CommentsBS4954-1:197
9、3 BSI 01-2000 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Nomenclature 1 4 Instrumentation 2 5 Test for total pressure loss of primary air supply 3 6 Test for the relationship between primary air flow rate and nozzle pressure 4 7 Test for inl
10、et plenum leakage 5 8 Heat transfer measurements 5 9 Secondary air flow measurement 7 10 Interpretation of test results and rating 8 11 Thermal rating examples 10 Figure 1 Thermometer pockets in pipes of less than75mm diameter 11 Figure 2a Thermometer shield 12 Figure 2b Thermocouple shield 12 Figur
11、e 3 Typical open circuit test equipment 13 Figure 4 Typical closed circuit test equipment 14 Figure 5a Inverted tube pattern manometer 15 Figure 5b Piezometer ring 15 Figure 6 Test for total pressure loss of primary air supply typical arrangement 16 Figure 7 Air supply arrangement for leakage test 1
12、7 Figure 8a Location of inlet air temperature measuring stations bounded unit 18 Figure 8b Location of inlet air temperature measuring stations free standing unit 19 Figure 9 Air flow chamber 20 Figure 10 Determination of air volume flow rate 21 Figure 11 Thermal characteristics 22 Figure 12 Thermal
13、 rating example 23 Figure 13a Water temperature correction factor heating 24 Figure 13b Water temperature, correction factor cooling 24 Publications referred to 26BS4954-1:1973 ii BSI 01-2000 Foreword Part 1 of this British Standard has been prepared under the authority of the Refrigeration, Heating
14、 and Air Conditioning Industry Standards Committee, to meet the needs expressed by industry. Part2, dealing with acoustic testing and rating of induction units, will be published later. The Committee acknowledge their debt to the Heating and Ventilating Research Association for the Associations work
15、 in formulating the methods of testing which appear in this Part of the standard. This work was carried out under a Department of Trade and Industry contract. The test methods enable the thermal and aerodynamic performance of an induction unit to be evaluated at any water and air flow rate and tempe
16、rature within the range of the variables employed for the test. The aerodynamic test methods deal with four aspects of a units performance: 1) The pressure loss of the primary air supply. 2) The relationship between the primary air flow rate and the nozzle pressure. Since the inlet velocity profile
17、effects will be small, the data obtained in this test may be used by a site engineer to assist him in balancing an air distribution system. 3) The inlet plenum leakage flow rate. 4) The induction ratio. Two heat transfer test methods are given, one for operation over a limited range of temperatures
18、and the other for a wider range of temperatures. Examples of calculations from the test data are included. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British St
19、andard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to26, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorpora
20、ted. This will be indicated in the amendment table on the inside front cover.BS4954-1:1973 BSI 01-2000 1 1 Scope This British Standard specifies methods of test for induction units with water coils for either (or both) heating and sensible cooling duties. It gives instructions for the calculation, i
21、nterpretation and interpolation of the test results for the thermal and aerodynamic rating of the units. NOTEThe titles of the British Standards referred to in this Part of this standard are shown on page 26. 2 Definitions For the purposes of this British Standard the following definitions apply: 2.
22、1 induction unit an assembly in which the treated primary air, received under pressure from a central plant, is discharged at high velocity through a series of nozzles fitted within the unit. This high velocity discharge causes an induction process, inside the unit, and thus an inflow of secondary a
23、ir from the treated space into the unit. Some or all of the induced secondary air entering the unit may pass through a heat exchanger. The induced secondary air then mixes with the primary air and is discharged into the treated space 2.2 primary air conditioned air fed to the nozzles in an induction
24、 unit 2.3 secondary air air from the space being conditioned which is induced into the unit by the action of the primary air ejected from the nozzles. The secondary air generally passes through a heat exchanger 2.4 nozzle a device so designed as to give low energy loss and thus produce a maximum thr
25、ow by minimum entrainment 2.5 unitary type induction unit this type of induction unit is a discrete device, but several may be grouped and linked together by their primary air supply ducting 2.6 modular (continuous) type induction unit this type of induction unit consists of a series of sections, mo
26、dular in length, so designed as to enable them to be connected together to form a single unit completely filling the wall space allocated 2.7 reference nozzle this is one of the primary air supply nozzles which is selected as a reference nozzle for the purpose of comparing primary air pressures at d
27、ifferent times during the test procedure 2.8 reference air atmospheric air having a density of1.2kg/m 3at a temperature of20 C, a pressure of101325N/m 2 , and43% relative humidity 3 Nomenclature Symbol Definition Units A p Area of primary air supply duct m 2 A t Area of water supply tube m 2 c pw Sp
28、ecific heat capacity of water kJ/kg K H D Hydraulic diameter (=4 area/perimeter) mBS4954-1:1973 2 BSI 01-2000 The suffix r is used to denote reference conditions. A bar over the symbol indicates the mean of several test results. 4 Instrumentation 4.1 Temperature 4.1.1 The measurement of temperature
29、shall be by means of mercury-in-glass thermometers, resistance thermometers or thermocouple and potentiometer. Temperature measuring instruments shall comply with the requirements of BS1041. 4.1.2 The water temperature at entry and exit shall be measured by means of instruments inserted in oil-fille
30、d pockets similar to those shown inFigure 1. If mercury-in-glass thermometers are used they shall comply with the requirements of BS593, partial immersion ranges, and shall be graduated in intervals not exceeding0.1 C. 4.1.3 All temperature measuring instruments shall be calibrated against a referen
31、ce thermometer accurate to0.05 C, which has been calibrated by NPL or another approved authority. 4.1.4 Air temperature measuring instruments shall be shielded against radiation by means of shields similar to those shown inFigure 2. K W Hydraulic pressure drop temperature correction factor m Water m
32、ass flow rate kg/s p b Barometric pressure N/m 2 p F Static pressure upstream of flowmeter N/m 2 p i Static pressure at primary air inlet N/m 2 p ir Static pressure at primary air corrected to reference conditions N/m 2 p T Total pressure N/m 2 p R Pressure at reference total pressure tube N/m 2 %p
33、c Coil hydraulic pressure drop corrected for height N/m 2 %p ct Coil hydraulic pressure drop at reference temperature of10C(cooling), 80 C (heating) N/m 2 %p F Pressure drop across air flowmeter N/m 2 Q a Heat transferred under free delivery kW Q c Heat transferred with unit connected to air flow ch
34、amber kW Air density kg/m 3 F Air density at flowmeter kg/m 3 w Water density kg/m 3 t a Secondary air inlet temperature C t i Primary air inlet temperature C t F Air temperature at flowmeter C t wi Inlet water temperature C t wo Outlet water temperature C V p Primary air volume flow rate m 3 /s V F
35、 Primary air volume flow rate at flowmeter m 3 /s V s Secondary air volume flow rate m 3 /s V T Total (V p + V s ) air volume flow rate m 3 /s Symbol Definition UnitsBS4954-1:1973 BSI 01-2000 3 4.2 Water flow measurement 4.2.1 The measurement of water flow shall be preferably by means of direct weig
36、hing, (for water temperatures above90 C it is advantageous to use one of the methods described in BS1042). The water leaving the test rig shall be collected in vessels of known weight, and weighed on a weighing machine, having an accuracy of0.1% over the range of weights used in the test. The weight
37、 of each vessel used shall not exceed50% of the weight of its normal contents. Precautions shall be taken to minimize evaporation from the vessels awaiting weighing. The net weight of each charge shall be recorded by weighing the vessel both after emptying the previous charge and after filling. 4.2.
38、2 The above method is suitable for water exit temperatures up to about90 C using the arrangement of equipment shown inFigure 3. For higher water exit temperatures it may be necessary to cool the water leaving the unit before it is discharged into the measuring vessel. Care shall be taken to check an
39、y after-cooler for leaks. 4.2.3 An alternative to the method of direct weighing described in4.2.1 is shown inFigure 4, together with a suitable water supply system for water temperature above90 C. 4.3 Air flow measurement 4.3.1 Air flow measurement shall be in accordance with BS1042-1, or alternativ
40、ely a flowmeter may be calibrated in situ using the methods given in BS1042-2 1) . 4.3.2 Leakage flow rates may be measured by means of a calibrated variable area flowmeter or integrating air flowmeter. 4.4 Pressure measurement 4.4.1 Wall static pressures shall be measured with static taps conformin
41、g to the requirements specified in BS1042-2 1) . 4.4.2 Pressures shall be measured by means of an instrument with scale intervals no greater than2% of the indicated reading with the exception of pressures below50N/m 2 , in which case the maximum interval shall be to1N/m 2 . 4.4.3 Static pressures sh
42、all be measured with liquid-filled manometers. An inverted U-tube manometer, similar to that shown inFigure 5 shall be used for the measurement of hydraulic pressure drop. 4.4.4 The minimum differential pressures for flow measurement shall be25N/m 2for inclined U-tube and micro-manometers and500N/m
43、2for vertical U-tube manometers. 5 Test for total pressure loss of primary air supply 5.1 A test duct of cross-sectional dimensions equal to the nominal dimensions of the primary air inlet, and of minimum length six hydraulic diameters (H D ), shall be connected to the primary air inlet. NOTEIf the
44、inlet is not of circular or rectangular cross section a transition section of minimum length2H Dand of constant area may be connected between the primary air inlet and the test duct. 5.2 A flow straightener shall be located at the upstream termination of the test duct. A wire mesh screen (having a f
45、ree area from60% to70%) shall be located two test duct hydraulic diameters downstream of the flow straightener. A ring of four static pressure taps shall be fitted at a point two test duct hydraulic diameters from the downstream termination of the test duct. The test duct shall be connected to an ai
46、r supply system arranged similarly to the system shown inFigure 6. The supply air temperature is to be measured at the flowmeter and on the test duct centre-line one test duct hydraulic diameter upstream of the pressure taps. 5.3 The test shall be carried out and results analysed in the following wa
47、y: 1) Set the primary air flow damper (if fitted) fully open. 2) Start the air supply fan and set the air flow rate to the desired level. The results may be recorded when the supply air flow rate has not varied by more than2% over a period of five minutes and the air inlet temperature has not varied
48、 by more than2 C over a similar period. 1) In course of preparation.BS4954-1:1973 4 BSI 01-2000 3) The following data shall be recorded: 4) Calculate the inlet static pressure for the reference air density of1.2kg/m 3from the equation: where: 5) Calculate the air flow rate for the reference air dens
49、ity of1.2kg/m 3from the equation: where: 6) Calculate the total pressure loss from the equation: where: 6 Test for the relationship between primary air flow rate and nozzle pressure The balancing of an induction unit system is usually carried out by estimating the primary air flow rate from the total pressure measured at a reference nozzle. If this test is to be of value the reference nozzle must be clearly marked, and a total head tube of sufficient size connected to the reference nozzle. 6.1
