Design principle of pressure-type level gauges

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A pressure-type level gauge is a pressure sensor used for measuring liquid levels. It operates on the principle that the static pressure of the liquid being measured is proportional to its height; it utilizes advanced isolated diffused silicon sensing elements or ceramic capacitive pressure sensors from abroad to convert this static pressure into electrical signals. After temperature compensation and linear correction, these signals are transformed into standard electrical signals (usually 4–20 mA/1–5 VDC). 　　The hydrostatic immersion type level transmitter (level gauge) is suitable for measuring the level of various fluids in systems and industries such as petrochemicals, metallurgy, power generation, pharmaceuticals, water supply and drainage, and environmental protection. Its sophisticated design, simple calibration, and flexible installation make it easy for users to use. Standard signal output methods such as 4–20mA, 0–5V, and 0–10mA can be selected by the user according to their needs. 　　Pressure-type level gauge, solid-state structure, no moving parts, high reliability, long service life. Easy to install, simple in structure, economical and durable. It has good stability, with long-term stability at full scale and zero point reaching 0.1%FS/year. 　　Working principle: Based on the principle of static pressure measurement: When the level transmitter is placed at a certain depth in the liquid to be measured, the pressure acting on the sensor’s surface in contact with the liquid is given by the formula: Ρ = ρ·g·H + Po. Where: P is the pressure acting on the sensor’s surface in contact with the liquid; ρ is the density of the liquid being measured; g is the local acceleration due to gravity; Po is the atmospheric pressure at the surface of the liquid; H is the depth at which the transmitter is submerged in the liquid. Meanwhile, the pressure of the liquid is introduced into the sensor’s positive pressure chamber through stainless steel tubes, while the atmospheric pressure Po at the liquid surface is connected to the sensor’s negative pressure chamber, thereby canceling out Po on the back side of the sensor. As a result, the pressure measured by the sensor becomes ρ·g·H. Clearly, by measuring this pressure P, it is possible to determine the depth of the liquid level. 　　Measurement range: 1. Process: Diffusion silicon, ceramic capacitor, sapphire, or capacitor – any of these can be chosen; split-type or integrated type is also available. 　　2. Range: 0---0.5---200 meters. 　　3. Output: 4---20mA (2-wire system). 　　4. Power supply: 7.5---36VDC, 24VDC is recommended. 　　5. Used for level measurement in clean water, wastewater, and saline water. The information was collected and provided by Huaheng Transmitter Manufacturer.