HG/T20570.10 about noise calculation

I have made several designs with reference to this specification, mainly the prediction of steam target noise and the noise reduction of pipe covering materials. I checked CNKI and could not find the reference source of LA=110+20lgQ-20lgD in 20570. It seems to be an empirical formula proposed by the design institute when writing 20570. The process design manual of the Medical Engineering Institute did not include this formula. As for whether the unit is kg/h or t/h, there is very little information online. Other noise calculation specifications such as HJ2.4 or SH3146 do not have this formula. You might as well calculate it separately using t/h and kg/h, and then use other formulas to verify it to see which one is closer. The verification formula adopts the formula in Ma Daquan's "Noise and Vibration Control Engineering Manual", which is the subsonic injection formula in 20570.10, which is equivalent to not distinguishing between blocking injection and subsonic injection. The example question still uses the muffler selection case in 6.0.3 in 20570.10, hot air, 260°C, Qv=12000m3/h, D=150mm, pressure 0.57MPa.a , calculate the sound pressure level at 1 meter in the 45° direction. ①LA=110+20lgQ-20lgD, put into t/h unit, LA=87.15dbA, obviously the value is too low, because it is venting, the flow rate is 188m/s, which is equivalent to Mach 0.5. For example, the flow rate at the safety valve outlet is louder than the sound of steam target shooting. ②LA=110+20lgQ-20lgD, bring in kg/h unit, LA=150.29dbA. ③The subsonic injection formula calculates LA = 156.87dbA, which is close to ②. That is to say, it is more reasonable to choose kg/h. The flow rate should be brought in according to kg/h. I think the specification is okay.

The controversy over this unit is indeed worthy of serious consideration, and the poster is very meticulous about it. I will add a few verification ideas: You can check the preparation instructions or article instructions of HG/T20570.10 (some standards have supporting interpretation materials). They usually give the formula derivation process or quote the source of the formula to see which unit system is used in the original document. Select a known working condition (such as a scene where flow, pressure, and temperature all have clearly measured noise) and substitute kg/h and t/h into the formula for calculation. Compare the two results with the actual measured values. You can basically judge which one has a higher degree of agreement. If the standard refers to API or ISO, directly reproducing the units of the corresponding formula in the original standard is the most convincing evidence. There are standard databases on the Internet where you can download the original documents. However, it should be noted that the coefficients of the formulas under different engineering unit systems may be modified accordingly, and simply changing the units is not enough. If it is really impossible to confirm, it is recommended to write directly to the National Chemical Engineering Construction Standards Editing Center or the Standards Institute of the Ministry of Chemical Industry for consultation. They usually have dedicated personnel to explain the standard terms. In this way, you can get a written reply, which will make it easier to explain the subsequent plan review and acceptance.