GB/T1236-2000 “Performance Testing of Standardized Ducts for Industrial Ventilators“, adding Chapter 27 “Rectifiers“; Added Appendix C “Wind Chamber Leakage Test Method“; Added Appendix E “Input electrical power consumed by ventilation fan devices“; Added Appendix F “Optimal Methods for Performance Testing“; In Chapter 30, Chapter 31, Chapter 32, and Chapter 33, there is an introduction to the calculation methods for test results of different test devices The first scenario of “simplification method“ in the corresponding chapter of the original standard has been deleted: the reference Mach number is less than 0.15 and the pressure ratio is greater than 1.02.
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DESCRIPTION
The comparison between the old and new versions of GB17713-2022 "Range hoods and other cooking smoke suction and exhaust devices" and the 2011 version is as follows:
Appendix A Air Performance Test Method:
1、 New Overview: The air performance test of the equipment shall be conducted in accordance with this appendix. The test device is based on Chapter 30 of GB/T 1236-2017, and uses an A-type test device with multiple nozzles in the air chamber to measure the flow rate. When the pressure of the instrument is less than 1000Pa and the reference Mach number does not exceed 0.15, the influence of air compressibility and humidity on the test results is ignored.
2、 Adjusted the requirements for the experimental setup:
The air performance test methods for exhaust range hoods in Appendix C and cyclic range hoods in Appendix D of the 2011 version have been merged and adjusted, and unified as air performance test methods. The new standard requirements are as follows:
A.2.2、 The air inlet of the tested instrument should be in a free space and connected to the testing device in the manner shown in Figure A.1. The connection between the external exhaust equipment and the inlet common section pipeline of the test device can use the transition cover provided by the manufacturer (excluding cover parts such as check valves), but it is not necessary to install the accompanying exhaust pipe. If there are additional filtering devices in the design of the equipment, clean filtering devices should be installed. When connecting external instruments to the testing device, the length of the connecting pipeline should be greater than 5 times the diameter of the pipe. The circulating device should be directly connected to the air chamber, and the size of the air chamber should be adapted to the outlet size of the tested device
Complete characteristic curve of 16.6 ventilation fan
The complete characteristic curve of a ventilation fan ranges from zero static pressure to zero inlet volumetric flow rate.
However, typically only a portion of the curve is used Suggest that the supplier specify the range of inlet volumetric flow suitable for the operation of the ventilation fan Therefore
The characteristic curve of the ventilation fan can be limited to the normal operating range; If the flow rate exceeds the normal working range of the imported volume, the measurement uncertainty is prone to increase
There will be unfavorable flow patterns at the import and export points.
16.7 Test under Specific Operating Conditions
Specific operating condition tests should consist of at least three test points that can determine a small portion of the ventilation fan characteristic curve, including specific inlet points
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22.2.2 As shown in Figure 16, the nozzle should be elliptical, but it can also be approximated using two Three arcs of different radii, as long as they are in the normal direction at any point
The difference from the ellipse should not exceed 0.015d.
22.2.3 The nozzle throat diameter d should be measured at the short axis of the ellipse and the nozzle outlet, with a measurement accuracy of 0.001d; four measurements should be taken at intervals of 45 °
The deviation between the individual value and the average value shall not exceed ± 0.002d.
The average diameter at the throat inlet will be greater than 0.002d, but not less than the average diameter at the nozzle outlet.
22.2.4 The inner surface of the nozzle should be flat and smooth, and a ruler should not scratch the surface. The peak to peak value of the uneven surface should not exceed 0.001d.
If the nozzle is used for the air chamber, the type shown in Figure 16 should be adopted.
22.3 Import Area
When positioning the nozzle, the distance between the centerline of each nozzle and the wall of the air chamber should not be less than 1.5d; the minimum center of any two nozzles used simultaneously
The distance is 3d, where d is the diameter of the larger nozzle.
22.4 Multi nozzle Characteristics
When the pressure ratio of the flow meter rd>0.9 (i.e., the flow meter differential pressure △ p<10 kPa), the multi nozzle device made according to the requirements of 22.3 may not be required
Used after calibration.
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