Manometers are used in the fuel gas (LP and natural) industry to measure gas pressure. In the U.S., LP gas systems used for home heating and cooking are regulated at about 10 inches of water column which is much less than 1 pasig. I don’t recall the regulated gas pressure for natural gas, but I think it’s around 8 inches of water column. Manometers measure pressure by how far the pressure moves a column of water. In some cases mercury is used instead of water. The one pictured here is used in metric measurements but does the same thing. They would be used in any industry that requires measurement of low gas pressures. I hope my explanation makes sense. I tend to ramble.
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