GB/T 14294-1993 Modular air conditioning units

This standard specifies the classification, basic specifications, technical requirements, test methods, inspection rules and marking, packaging, transportation and storage of modular air-conditioning units. This standard applies to units without cold and heat sources, with water as the refrigerant and water or steam as the hot coal, with functional sections as the combination unit, and capable of completing several processing functions such as air transportation, mixing, heating, cooling, dehumidification, humidification, filtering, and silencing. Units with brine or ethylene glycol as the refrigerant and electric heaters can be used as a reference. This standard does not apply to units with their own cold and heat sources and direct evaporation coils. GB/T 14294-1993 Modular air-conditioning units GB/T14294-1993 standard download decompression password: www.bzxz.net

Engineering Construction Standard Full-text Information System
National Standard of the People's Republic of China
GB/T14294—93
Combined air-conditioning units
Central-station air handling unitsConstruction standard
Issued on April 24, 1993
Implementation on December 1, 1993
Issued by the State Bureau of Technical Supervision
Engineering Construction Standard Full-text Information System
W Engineering Construction Standard Full-text Information System
National Standard of the People's Republic of China
Combined air-conditioning units
Central-station air handling units 1 Subject content and scope of application
GB/T14294—93
This standard specifies the classification, basic specifications, technical requirements, test methods, inspection rules and markings, packaging, transportation and storage of combined air-conditioning units (called units).
This standard applies to units without cold and heat sources, with water as the refrigerant and water or steam as the heat medium, with functional sections as combined units, and capable of completing several processing functions such as air transportation, mixing, heating, cooling, dehumidification, humidification, filtering, and silencing. Units with brine or ethylene glycol as the refrigerant and electric heaters can be used as a reference. This standard does not apply to units with their own cold and heat sources and direct evaporation coils. 2 Reference standards
GB1236
Test method for aerodynamic performance of ventilator
GB1449
GB2406
GB2576
GB2577
GB2624
GB8070
GB9068
Test method for bending performance of glass fiber reinforced plastics Test method for combustion performance of plastics Oxygen index method Test method for insoluble content of resin in fiber reinforced plastics Test method for resin content of glass fiber reinforced plastics Flow measurement throttling device Part 1 Throttling device is angle connection pressure, flange pressure standard orifice plate and angle connection pressure standard Nozzle
Air distributor performance test method
Determination of noise sound power level of heating, ventilation and air conditioning equipment-engineering method
GB10223
GB10891
GB12218
3 Terminology
Air cooler and air heater performance test method Air handling unit safety requirements
General ventilation air filter performance test method 3.1 Combined air conditioning unit
An air handling equipment assembled from various air handling functional sections without cold and heat sources. This unit should be able to be used in air conditioning systems with air duct resistance equal to or greater than 100Pa.
3.2 Unit functional section
A unit with one or more air treatment functions. The functional sections of the unit may include: air mixing, flow balancing, coarse filtration, medium filtration, high or sub-high efficiency filtration, cooling, primary and secondary heating, humidification, air supply fan, return fan, intermediate, water spray, silencer, etc. 3.3 Rated air volume
The volume flow of air passing through the unit per hour under standard air conditions, in m\/h. State Technical Supervision Bureau 1993-04-24 approved Engineering Construction Standard Full Text Information System
1993-12-01 implementation
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3.4 ​​Unit full pressure
The sum of the dynamic pressure and static pressure at the air outlet after the unit overcomes its own resistance, in Pa. 3.5 Rated cooling capacity
The total heat removal of the unit under the specified test conditions, that is, the sum of the sensible heat removal and latent heat removal. The unit is kW. 3.6 Rated heating capacity
The total sensible heat supplied by the unit under the specified test conditions, in kW. 3.7 Air leakage rate
The ratio of the air leakage volume of the unit to the rated air volume, expressed in %. 3.8 Sectional wind speed uniformity
Refers to the percentage of points where the absolute value of the difference between the wind speed at any point on the section and the average wind speed does not exceed 20% of the average wind speed to the total number of measuring points.
3.9 Standard air state
Refers to the air state at a temperature of 20°C; a pressure of 101.3 kPa; and a density of 1.2 kg/m3. 4 Classification and specifications
4.1 Classification
4.1.1 According to the structural type
Horizontal,
Vertical;
Suspended;
By box material
Metal;
Glass fiber reinforced plastic (GRP); Composite materials;
By usage characteristics
General purpose unit,
Fresh air unit;
Variable air volume unit;
Purification unit;
4.2 Basic specifications and parameters
The basic specifications of the unit are expressed in rated air volume, arranged in segmented arithmetic progression, see Table 1. Table 1 Basic specifications
Specification code
Rated air volume
Specification code
Rated air volume
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100000
120000
140000
160000
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4.2.2 The cooling capacity and heating capacity of the unit shall meet the following requirements under the specified test conditions. a.
The air drop of the rated cooling capacity of the unit shall not be less than 17kJ/kg, and the air drop of the fresh air unit shall not be less than 34kJ/kg. b.
The air temperature rise of the heating capacity of the unit shall not be less than
When heated by steam, the temperature rise is 20℃;
When heated by hot water, the temperature rise is 15℃.
4.3 Model representation
Model example
-Purpose characteristics
Box material
Specification code (10°m/h)
Structural type
Table 2 Classification code table
Classification items
ZKL5-BX
Structural type
Box material
Purpose characteristics
Indicates a combined vertical fiberglass fresh air unit with a rated air volume of 5000m/h. ZKW10-JT
Suspended
Hybrid
General unit
Fresh air unit
Variable air volume unit
Purification unit
Indicates a combined horizontal metal air conditioning unit with a rated air volume of 10,000 m/h. ZKW20-JBXbzxz.net
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Combined air conditioning unit code
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Indicates a combined horizontal metal variable air volume fresh air unit with a rated air volume of 20,000 m/h. 5 Technical requirements
5.1 Basic requirements
5.1.1 The unit shall be manufactured in accordance with the drawings and technical documents approved by the prescribed procedures. 5.1.2 The basic specifications and parameters of the unit shall comply with the provisions of Article 4.2. 5.1.3 The structure of the unit shall meet the following requirements a.
When the windward velocity of the cooling coil exceeds 2.5m/s, a water retaining plate shall be installed. b.
The water spray section shall have an observation window, a water retaining plate and a water filter. The unit shall be equipped with a drain outlet, and the discharge shall be unobstructed, without overflow and leakage. c.
The insulation layer of the unit box and the wall panel shall be firmly and densely combined. The thermal resistance of the wall panel insulation shall not be less than 0.68m\K/W, and the box shall have anti-cold bridge measures.
The inspection door of the unit shall be tight, flexible, openable from both inside and outside, and lockable. e.
The fan outlet of the unit shall have a flexible pipe, and the fan shall be equipped with a vibration isolation device. The box of each functional section shall have sufficient strength and shall not be deformed during transportation and after starting, running and stopping. The airflow on the cross section of the unit should not short-circuit. The unit should have measuring holes and test instrument interfaces. i
The heating section of the FRP air-conditioning unit should have insulation measures. 5.1.4 The fan, cold and hot coils, filters, humidifiers and other parts configured in the unit should comply with the relevant national standards. 5.1.5 The surface of the components made of ferrous metal in the unit should be rust-proofed and anti-corrosion treated. 5.2 Appearance requirements
5.2.1 The outer surface of the unit should be free of obvious scratches, rust spots and indentations, the surface should be smooth, the spray layer should be uniform, the color should be consistent, and there should be no flow marks, bubbles and peeling. 5.2.2 The outer surface of the FRP unit should have a uniform gel coat layer, the surface should be smooth and flat, without cracks, bubbles and defects, and the color should be uniform. The inner surface should be smooth and flat, and the fibers should not be exposed. The edges should be neat, the thickness should be uniform, there should be no stratification, and the processed sections should be sealed with resin. 5.2.3 The unit should be cleaned and there should be no debris inside the box. 5.3 Performance requirements
5.3.1 Startup
a. The unit can start and operate normally under rated voltage. b. After the unit is assembled at the use site, it should be inspected and tested. 5.3.2 Coil pressure resistance performance
There should be no leakage under one of the following conditions. The water pressure test pressure should be 1.5 times the design pressure, with an allowable deviation of ±0.02MPa, and the pressure should be maintained for at least 3min. a.
b. The air pressure test pressure should be 1.2 times the design pressure, with an allowable deviation of ±0.02MPa, and the pressure should be maintained for at least 1min. 5.3.3 Rated air volume and total pressure
Under the test conditions specified in Table 4, the measured air volume value shall not be less than 95% of the rated value, and the measured total pressure value shall not be less than 88% of the rated value. 5.3.4 Under the test conditions specified in Table 4, the actual power value of the unit shall not exceed 10% of the rated value. 5.3.5 Air leakage rate
When the static pressure inside the unit is maintained at 700Pa, the air leakage rate of the unit shall not exceed 3%. For units used in purification air conditioning systems, the static pressure inside the unit shall be maintained at 1000Pa. When the cleanliness level is lower than Class 1000, the air leakage rate of the unit shall not exceed 2%; when the cleanliness level is higher than or equal to Class 1000, the air leakage rate of the unit shall not exceed 1%.
5.3.6 Rated cooling and heating capacity
The actual measured values ​​of the cooling and heating capacity of the unit shall not be less than 93% of the rated value. Engineering Construction Standard Full-text Information System
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5.3.7 Air heat exchange efficiency of the water spray section. When the water spray pressure is less than 245kPa, the heat exchange efficiency of the air shall not be less than 80%. 5.3.8 The water flow through the water baffle shall not exceed 4X10*kg/kg. 5.3.9 The filtration efficiency and resistance of the air filter shall comply with the provisions of Table 3. Table 3 Filter efficiency and resistance
Atmospheric dust particle size (μm)
Counting efficiency E(%)
Resistance (Pa)
20E<80
20E<70
5.3.10 Condensation test, according to the method of 6.3.10, there shall be no condensation dripping on the surface of the unit. High and medium efficiency
70E<99
5.3.11 Condensate removal capacity, the unit operates under the test conditions of Table 4, and the condensate is discharged smoothly without overflow. 5.3.12 Unit noise
When the rated air volume of the unit is 2000~5000m/h, the unit noise sound pressure level shall not exceed 65dB (A). When the rated air volume of the unit is 6000~10000m3/h, the unit noise sound pressure level shall not exceed 70dB (A). When the rated air volume of the unit is 15000~25000m/h, the unit noise sound pressure level shall not exceed 80dB (A). When the rated air volume of the unit is 30000~60000m/h, the unit noise sound pressure level shall not exceed 85dB (A). When the rated air volume is 80000~160000m/h, the unit noise sound pressure level shall not exceed 90dB (A). 5.3.13 Unit vibration
When the fan speed is greater than 800r/min, the vibration speed of the unit shall not exceed 4mm/s. When the fan speed is less than or equal to 800r/min, the vibration speed of the unit shall not exceed 3mm/s. 5.3.14 The uniformity of the cross-section wind speed shall be tested according to method 6.3.14 and shall not be less than 80%. 5.3.15 The safety performance requirements shall comply with the provisions of GB10891. 5.4 Material requirements
5.4.1 The steel plates, profiles, pipes, etc. used in the unit shall comply with the relevant standards. 5.4.2 When the unit casing is made of FRP, the requirements are as follows: a.
Resin content (excluding gel coat layer) is controlled at 45%~55% sub-high efficiency
<120
Degree of curing: not less than 80% for unsaturated polyester resin FRP, and not less than 90% for epoxy resin FRP. Bending strength: not less than 147MPa for unsaturated polyester resin FRP, and not less than 196MPa for epoxy resin FRP. Flame retardant performance: The oxygen index of FRP is not less than 30. 5.4.3
The thermal insulation and sound insulation materials used in the unit casing should be non-toxic, non-corrosive, odorless, and have the characteristics of flame retardancy or self-extinguishing and not easy to absorb water. 6 Test method
6.1 General requirements
6.1.1 The test unit should be tested as a whole unit according to the functional sections. 6.1.2 The test unit should be assembled and installed according to the requirements of the product manual. Unless otherwise specified in the test method, no special treatment measures are allowed.
6.2 Test conditions
6.2.1 The test conditions should comply with the provisions of Table 4. Engineering Construction Standard Full-text Information System
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Air volume, total pressure, power
Cooling capacity
Cooling capacity of fresh air unit
Thermal performance of water spray section
Heating supply
Fresh air unit
Heating supply
Condensate removal
Overwater
Air leakage||t t||Inlet air state
Dry bulb temperatureWet bulb temperature
Inlet water temperature
60/902)
60/902)
Test condition
Water supply state
Inlet and outlet
Water temperature difference
Water supply
Spray water pressure
Note: 1) Inlet water temperature refers to the chilled water supply temperature, and the inlet and outlet water temperature difference refers to the temperature difference between the outlet and the chilled water supply. Steam supply state
Gage pressure
2) The inlet water temperature of 60℃ is the test condition for the heating capacity of the dual-purpose coil, and 90℃ is the test condition for the heating capacity of the heating coil. 3) The water supply capacity is calculated by the water flow rate in the coil = 1m/s and the water flow area. 6.2.2
2 The allowable deviation of the test conditions and test operations shall comply with the provisions of Table 5. Table 5 Test allowable deviation
Allowable deviation
Air state at inlet and outlet
Water supply state
Dry bulb temperature, ℃
Wet bulb temperature, ℃
Cold water inlet temperature, ℃
Hot water inlet temperature, ℃
Water flow rate, %)
Water supply pressure (gauge pressure), kPa
Steam supply state
Air volume, %)
Total air pressure, Pa
Voltage, %
Note: 1) The % in the table refers to the percentage of the rated value. Steam supply pressure, kPa
3 The instrument used for the test shall comply with the provisions of Table 6. 6.2.3
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Test Condition Tolerance
Add Group Exit Golden House
The first
Maximum
Maximum
Test Operation Tolerance
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Measurement Parameters
Measuring Instruments
Glass Mercury Thermometer, Resistance Thermometer, Thermocouple Thermometer
Micromanometer (inclined, compensated or
automatic Sensing type)
U-shaped mercury manometer or manometer of equivalent accuracy
Steam pressure gauge
Water pressure gauge
Atmospheric pressure gauge
Flow meter, weight type or volumetric liquid
Voltage meter
Pitto tube
Anemometer
Voltmeter
Ammeter
Power meter or voltage and current meter
Tachometer
Sound level meter
Contact vibration meter
Note: 1) The minimum pressure difference should be 25Pa when measuring dynamic pressure. 2) Refers to the percentage of the measured value.
6.3 Performance test methods
Start-up test
Table 6 Test instruments
Measurement items
Air during hot and cold performance test
Inlet and outlet dry-bulb temperature and heat exchange
Equipment inlet and outlet temperature
Other temperatures
Air static pressure and dynamic pressure
Water resistance, steam pressure drop
Steam supply pressure
Water pressure in water spray section
Atmospheric pressure
Water flow rate of heat exchanger, steam condensate
Amount of water flow rate in spray room, etc.
Sectional wind speed uniformity, etc.
|Electrical parameters of fan input
Fan speed
Unit noise
Fan section vibration speed
Condensate volume, etc.
Instrument accuracy
According to Figure A1
GB2624
GB8070 Appendix B
GB9068
Test the unit under rated voltage conditions, start it, run it stably for 5 minutes, cut off the power supply, stop it, and repeat it at least three times; check whether there are any loose parts, noise, heat and other abnormal phenomena; variable air volume units should be started at maximum and minimum air volumes. 6.3.2 Coil pressure resistance performance test
Test the pressure under the test pressure conditions specified in 5.3.2. 6.3.3 Rated air volume and full pressure test
The test shall be carried out according to the method specified in Appendix A (Supplement) or Appendix B (Supplement). During type inspection, when the rated air volume is less than or equal to 60,000 m/h, the test shall be carried out according to the method in Appendix A. When the rated air volume is equal to or greater than 80,000 m/h, the test may be carried out according to the method in Appendix B. Engineering Construction Standard Full Text Information System
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6.3.4 Input power test
Measured according to the method specified in Appendix A.
6.3.5 Leakage test
Measured according to the method specified in Appendix C (Supplement). 6.3.6 Cooling and heating test
a. The cooling and heating shall be tested under the test conditions specified in Table 4 according to the method in Appendix D (Supplement). b. The cooling and heating capacity can also be calculated by directly quoting the coil heat transfer coefficient formula obtained by the method specified in GB10223, and the on-site verification shall be carried out according to the method specified in Appendix E (reference). 6.3.7 Air heat exchange efficiency of the water spray section
Test according to the method in Appendix D.
6.3.8 Water flow test of water baffle
Test according to the method of D2.2.8 in Appendix D. 6.3.9 Air filtration efficiency and resistance test. Carry out filter efficiency and resistance test according to the test method specified in GB12218. 6.3.10 Condensation test
Under the conditions of the dew point temperature of the operating environment of 22.8~26.2℃ and the unit water supply temperature of 7℃, the unit is operated for 6 hours for continuous cooling, and the condensation on the unit surface is checked.
6.3.11 Condensate removal capacity test
According to the test conditions specified in Table 4, fill the condensate tray with water to the drain port in advance, run the unit for 4 hours, and check the drainage condition. 6.3.12 Noise test
The noise of the unit should be measured according to the engineering measurement method specified in GB9068. 6.3.13 Vibration test
Use the instruments specified in Table 6 to measure the vibration velocity in the three-dimensional directions perpendicular to each other at the four corners of the bottom plate of the test unit; a.
The maximum value is the vibration velocity of the unit.
6.3.14 Section wind speed uniformity test
At 200mm from the windward section of the coil or filter, evenly distribute wind speed measurement points according to Figure B1 in Appendix B; a.
b. Use an anemometer to measure the wind speed at each point, and calculate the percentage of points where the difference between the measured wind speed and the average wind speed does not exceed 20% of the average wind speed in the total number of points.
6.3.15 Safety performance should be tested in accordance with the provisions of GB10891. 6.4 Appearance inspection
Inspect by visual inspection
6.5 Material test
6.5.1 The resin content test of FRP should be in accordance with the method specified in GB2577. 6.5.2 The curing degree test of FRP should be in accordance with the method specified in GB2576. 6.5.3 The bending strength test of FRP should be in accordance with the method specified in GB1449. 6.5.4 The test method for oxygen index of flame retardant performance of FRP shall comply with the provisions of GB2406. 7 Inspection rules
7.1 Inspection classification and inspection items
7.1.1 Unit inspection is divided into factory inspection (delivery inspection) and type inspection. 7.1.2 Inspection items are as shown in Table 7.
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Inspection item name
Main component inspection
Safety requirements
Start-up and operation
Coil pressure resistance performance
Air volume and total pressure
Input power
Air leakage rate
Cooling capacity, heating capacity
Water spray section air Air heat exchange efficiency
Water flow through water baffle
Filtration efficiency and resistance
Condensation test
Condensate removal capacity
Sectional wind speed uniformity
GRP material properties
a. Resin content
b. Curing degree
c. Bending strength
d. Flame retardant performance
Note: For metal air-conditioning units, item 18 is not required. 2 Factory inspection
Inspection items
Clause(s) of this standard
5.2.1~5.2.4, 6.4
5.3.15, 6.3.15
5.3.1, 6.3.1
5.3.2, 6.3.2
5.3.3, 6.3.3
5.3.4, 6.3.4
5.3.5, 6.3.5
5.3.6, 6.3. 6
5.3.7、6.3.7
5.3.8、6.3.8
5.3.9、6.3.9
5.3.10,6.3.10
5. 3.11,6.3.11
5.3.12、6.3.12
5.3.13、6.3.13
5.3.14,6.3.14
Each unit (each functional section) must be inspected and qualified by the inspection department of the manufacturer and accompanied by a quality inspection certificate before leaving the factory. 2 The factory inspection of the unit shall be carried out according to items 1, 2, 3, 4, and 5 in Table 7. Items 6 and 7 in Table 7, at least 7.2.2
units shall be sampled for every 20 units, and one unit shall be sampled for annual production of less than 20 units. 3 The FRP unit shall also be tested for 18 items in Table 7, of which a., b., and d. shall be tested unit by unit. 7.2.3
7.3 Type inspection
Type inspection shall be carried out when the unit has any of the following conditions. When a new product is finalized;
When the structure, manufacturing process, materials, etc. of the finalized product are changed and affect the product performance; when production is resumed after more than one year of suspension;
When the production is transferred to another factory;
When mass production is carried out once every three years;
When the national quality supervision agency puts forward type inspection requirements. Engineering Construction Standard Full-text Information System
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7.3.2 The type inspection of the unit shall include all items in Table 7. 7.3.3
3 Type inspection sampling method: samples shall be drawn from qualified products that have passed factory inspection. The number of samples to be drawn shall be in accordance with Table 8. Table 8 Sampling Quantity
Inspection Quantity
(units)
Sampling Quantity
(units)
7.3.4 Judgment Rules
For a sample drawn, if one of the main items or two of the other items in the inspection items are unqualified, the sample shall be judged as unqualified b.
If one of the samples drawn is unqualified, another one shall be drawn. If the inspection is still unqualified, the batch of units shall be judged as unqualified products. 8 Marking, packaging, transportation and storage
8.1 Marking
Each unit shall have a product label and be fixed in a conspicuous position on the front. The label shall include the following contents. a.
Unit name and model;
Unit main technical parameters (rated air volume, total pressure, cooling capacity, heating capacity, rated voltage, current, power, speed, etc.); Unit dimensions: length × width × height;
Unit weight;
Factory number:
Factory date;
Manufacturer name.
The unit should be marked with working conditions, i.e. rotation direction, on and off, etc., and an electrical circuit diagram should be attached. 8.2 Packaging
Each functional section of the unit should be packed according to its own requirements and should be stable in the packing box. 8.2.2
The packing box should be tied firmly and tightly.
The packing box should contain packing list, product certificate, product installation and operation manual and other relevant technical documents. The packing box should have packing marks that are not easy to fade, including: product name and model;
product gross weight and net weight,
box body dimensions: length × width × height;
packing date;
arrival station (port) and receiving unit;
departure station (port) and shipping unit.
The packing box should have storage and transportation marks such as moisture-proof, rainproof, inversion-proof, no rolling, and handle with care. 8.3 Transportation and storage
8.3.1 The unit should not be hit, squeezed, thrown, or exposed to rain or snow during transportation. 8.3.2 The unit should be stored in a moisture-proof, rain-proof, and fire-proof place, and there should be no corrosive gas around it. 8.3.3
3 Fiberglass parts are not allowed to be exposed to the sun or heavy pressure.
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Appendix A
Test method for air volume and air pressure of modular air-conditioning unit (supplement)
Appendix A specifies the equipment, conditions and methods for the air volume and air pressure test of modular air-conditioning units. A1 Test equipment
A1.1 The test equipment consists of a test unit, a connecting pipe, and a test pipe. A1.2 The test equipment should be arranged in accordance with one of the methods in Figures 3, 4, and 5 of GB1236 and Figures A1 and A2 of this Appendix. When the arrangement is in accordance with GB1236, the requirements of 3.1, 3.3, 3.4 and 3.5 of the standard shall be met. When the inner diameter of the test tube is less than 400mm, an orifice flowmeter or an air flow nozzle device should be used. A1.3 The air flow nozzle and its measuring device used for air volume measurement are shown in Figures A3 and A4. a. The nozzle throat velocity must be between 15m/s and 35m/s; b. The nozzle processing requirements shall comply with the provisions of Appendix A of GB10223. A1.4 The test tube of the test device shall meet the following requirements. a. A single-outlet unit shall be equipped with an outlet air duct with a cross-sectional area equal to the outlet cross-sectional area of ​​the test unit. b. The multi-outlet unit shall be connected in the manner shown in Figure A5, and the cross-sectional area of ​​the duct shall be equal to the sum of the cross-sectional areas of each outlet of the test unit. A1.5 When testing a multi-inlet unit, all bypass air valves (such as the valve of the secondary return air) shall be closed. Only the air inlet valves flowing through each functional section of the unit shall be opened and placed in the fully open position. A2 Test conditions
A2.1 The test shall be carried out in accordance with the test conditions and test instrument requirements specified in Article 6.2 of this standard. A2.2 The test unit shall be an integral unit composed of several functional sections. A3 Test methods
A3.1 General
A3.1.1 The unit shall be tested at least five air volumes and full pressures at the rated speed of the fan. Each air volume shall be measured at least three times. A3.1.2 At each test air volume, measurements shall be made in accordance with Articles A3.2 to A3.7 of this Appendix. The outlet dynamic pressure, static pressure, outlet temperature, input power, speed, air volume and atmospheric pressure of the unit shall be measured. A3.2 Measurement of static pressure
A3.2.1 Connect the pressure-taking interfaces of four static pressure holes distributed at 90° to each other on the pipe wall of the measuring section to form a static pressure ring, connect one end of the pressure gauge to the ring, and connect the other end to the surrounding atmosphere. The reading of the pressure gauge is the static pressure of the unit. A3.2.2 The diameter of the static pressure hole on the pipe wall should be 1 to 3 mm. The edge of the hole must be at right angles and free of burrs. The inner diameter of the pressure interface pipe should not be less than twice the diameter of the static pressure hole.
A3.3 Measurement of dynamic pressure
A3.3.1 When measuring dynamic pressure with a Pitot tube, the straight tube of the Pitot tube must be perpendicular to the pipe wall, and the probe of the Pitot tube should face the airflow direction and be parallel to the axis of the duct. The location and number of measuring points should comply with the provisions of Table A1 and Figure A6. A3.3.2 Use a Pitot tube to measure the dynamic pressure at each point on the same cross section, and calculate the average dynamic pressure according to the following formula Pa-Pa+P+.
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