HG/T 20570.17 Issues regarding the design calculation of the liquid seal height in liquid seal design
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As shown in the screenshot, the specifications provide an algorithm for calculating the liquid seal height. However, I have two questions: 1. If P1 is negative pressure and P2 is atmospheric pressure, does one also need to take into account the height of the pipe section above H? For example, if P1 = -10 kPa and P2 = 0, then a height of 1 meter below the container should be ensured above H (i.e., the area marked in red). 2. What is the dimension of the relative density of this liquid? If it is relative density, then it should be 1; based on the values given above, the result would be very large, so it probably isn’t in units of m. If r is water, what should the value be?
1. If P1 is negative pressure while P2 is atmospheric pressure, the height of the water column corresponding to the negative pressure must be added to H when calculating the liquid seal height H. For example, if P1 = -10 kPa and P2 = 0, then the additional height of the water column required is equivalent to the height of a water column corresponding to 10 kPa. Convert the height of the water column using the density of water. The height of a water column corresponding to 10 kPa is 10 kPa/(9.80665 kN/m?) ≈ 1.02 m. So, add at least 1.02 meters on top of H. 2. The relative density of a liquid is defined with respect to the density of water; it is dimensionless, and the relative density of water is defined as 1. If it is water, the specific gravity should be filled in as 1. If the relative density of the liquid is different from that of water, calculations must be performed using the relative density of the actual liquid. .
Is another 1.02m of headroom required above H? Is that what you mean?
It’s just an equation of wasted effort! Don’t complicate simple problems
I just want to know whether to add a height on H
A margin needs to be available based on the calculations
If the relative density is taken as 1 for water, I have been using the calculation table in the attachment for many years, and it works fine. The part marked in red can be added to P1 or not, as some margin still needs to be left
After checking your gauge, I realized that my device has negative pressure at P1 and positive pressure at P2; it probably isn’t suitable for use. Sweat
Has the problem been solved? I also saw this here; I can’t understand this formula, and the units don’t match either. 10.2 should correspond to 1 atm of water column, and the liquid seal height should refer to H in the diagram