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Hydrostatic and Submersible Level Transmitters Working Principle and Installation


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Hydrostatic and Submersible level transmitters Working principle 

Hydrostatic and submersible level instruments use the head pressure of a fluid to infer level. It’s one of the oldest and most common methods around, and with good reason. Using pressure to measure level is a simple, reliable and for the most part cost effective solutions for a wide range of applications across many industries.

The equation to convert pressure (P) to level (L) is:

                                                                              𝐿 =𝑃/𝜌𝑔

Thus, the equation for pressure (P) generated is:

                                                                                    𝑃 = 𝐿𝜌𝑔


L = level of fluid in metres above the sensor

P = pressure in kPa

ρ = density of the fluid in g/cm3

g = gravity, (Can be considered 9.81 m/s2 for most locations)

Example 1 - Level where pressure is known

1. Pressure (P) of 4.9 kPa

2. Fluid density (ρ) of 1 g/cm3

3. Gravity (g) at sea level = 9.81 m/s2

            𝐿 =4.9/ (1 × 9.81) = 𝟎. 𝟓 𝒎𝒆𝒕𝒓𝒆


Example 2 – Pressure when level is known

1. Fluid level (L) is 0.5 metres

2. Fluid density of 1 g/cm3

3. Gravity at sea level = 9.81 m/s2

             𝑃 = 0.5 × 1 × 9.81 = 𝟒. 𝟗 𝒌𝑷

Installation Options


1. Top mount hydrostatic level transmitter with a flexible insertion length.

2. Rigid top mount hydrostatic level transmitter for pressurised vessels.

3. Rigid top mount hydrostatic level transmitter.

4. Hygienic gauge pressure/level for pharmaceutical or sanitary applications.

5. Gauge pressure or level transmitter.

6. Differential pressure transmitter for pressurised vessels.

7. Remote differential pressure transmitter.

8. Submersible level transmitter.