The liquid level metering cylinder and two conduits are formed. The cylinder is divided into two parts by the partition 5, the upper part of the container (gas phase part) and the negative pressure chamber 1 connected; the bottom side of the container through the gasifier 6 and positive pressure chamber 2 connected. The role of the gasifier is to make all the liquid gasification (if the heat uploaded into the pipeline is sufficient to make all the liquid gasification without gasifier), the pressure inside the gasifier is equal to the pressure of the positive pressure chamber. Gasifier pressure for the pressure on the liquid surface p and the pressure generated by the liquid column Hρg and (H for the height of the liquid column, ρ for the density of the liquid), and the negative pressure chamber pressure for P, then the positive and negative pressure chamber pressure difference for H ship. The negative pressure chamber has a tube 3 connected to the positive pressure chamber, in the positive and negative pressure chamber pressure difference Hρg, the liquid level of the liquid level tube rises, next to the liquid level of the indicator glass tube and the liquid level of the same height of the liquid level tube. Suppose the reading of the liquid level meter is h and the working liquid density is ρ′, then hρ′g=Hρg. h=Hρ/ρ′, H=hρ′/ρ. The indicated height of the liquid level meter and the actual liquid level height of the container can be converted by the above formula. For example, the density of liquid oxygen is p: 1140kg/m3, the density of tetrabromoethane ρ′ = 2960kg/m3, the indicated height of the liquid level meter is 500mm, then the actual liquid oxygen surface height is H = 500(mm) x 2960(kg/m3)/1140(kg/m3) = 1300mm.
When the liquid level fluctuates frequently, the air pressure entering the gasifier fluctuates with the liquid level, causing difficulties in reading, so the volume of the gasifier should be as large as possible in order to play a buffering role. This type of liquid level meter is widely used in small air separation equipment.
