Is a hydrostatic pressure transmitter the same as a static pressure transmitter?

In level work they mean the same: a transmitter that reads the static head of liquid to give level. Static pressure is the pressure of a liquid at rest, which is the hydrostatic head this method measures.

Can it measure level in a closed or pressurized tank?

Yes, but the gas pressure above the liquid must be cancelled out, using a differential pressure level transmitter or a diaphragm seal that references the head against the gas space.

How deep can a submersible hydrostatic transmitter go?

Standard submersible probes cover tens of meters; deep-well builds on a stainless cable reach hundreds of meters. Set the range and cable length to the maximum head and install depth.

Hydrostatic Pressure Transmitter: How It Works & Selection

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A hydrostatic pressure transmitter measures liquid level from the pressure that the liquid column exerts at the bottom of a tank or well. Because that pressure rises in step with the height of liquid above the sensor, a single pressure reading gives you the level. It is the workhorse method for storage tanks, process vessels, sumps, and wells, and it comes in two install styles: a submersible probe that hangs in the liquid, and a flush or flanged transmitter mounted on the vessel wall.

This page explains how the method works, how the two install types differ, and which Instranova model fits your tank. You may hear it called a hydrostatic level transmitter, a static pressure transmitter, or a pressure level transmitter; they describe the same hydrostatic principle.

How a hydrostatic pressure transmitter works

Level is read from hydrostatic pressure. At the bottom of a column of liquid, the pressure equals density times gravity times height, pressure = density x g x height. The transmitter sits at a fixed depth, senses that pressure on a diaphragm, and its electronics output a 4–20 mA or digital signal proportional to the head of liquid above it. Since the reading is derived from pressure, the transmitter shows true height only when it is scaled for the liquid’s density: a denser brine reads higher than water for the same level, so the span is set for your medium.

Submersible vs flush-mount types

Two install styles cover almost every tank. A submersible probe hangs from its cable so the sensor sits near the bottom; it is quick to fit, needs no tank penetration low down, and suits open tanks, wells, and sumps. A flush or flanged transmitter threads or bolts into the vessel wall near the bottom, with the diaphragm flush to the inside; it suits closed or pressurized vessels and sticky media that would coat a hanging probe.

Point	Submersible probe	Flush / flanged
Mounting	Hangs on cable from the top	Threaded or flanged on the wall
Best for	Open tanks, wells, sumps	Closed or pressurized vessels, sticky media
Closed vessel	Needs a reference or DP setup	Pairs with a DP transmitter for sealed tanks

For a sealed or pressurized vessel, the head pressure is referenced against the gas space with a differential pressure level transmitter or a diaphragm seal transmitter, so the gas pressure cancels out of the reading.

Choosing a hydrostatic pressure transmitter

Four points settle the choice:

Range and density. Set the span from the maximum head in the liquid you actually run, and give us the specific gravity so the unit reads true height.
Medium. Clean water takes a standard stainless probe; acids, alkalis, and slurries need a fluoropolymer wetted path; hot media call for a build that keeps the cell off the heat.
Tank type. Open tank or well favors a submersible probe; a closed or pressurized vessel uses a flush or DP arrangement.
Depth and cable. The cable length is set by how far the probe hangs, not by the range, so tell us both.

Hydrostatic transmitters in our range

SI-151 Hydrostatic Level Transmitter
The standard submersible probe for clean water tanks, reservoirs, and wells.

SI-302 anti-corrosive submersible level transmitter

SI-302 Anti-corrosive Submersible
PTFE wetted path for acid, alkali, sludge, and slurry.

Stainless steel submersible level transmitter

Stainless Steel Submersible
Gas-conducted build that keeps the sensor out of hot or corrosive liquid.

SI-PCM261 submersible pressure transducer probe

SI-PCM261 Submersible Probe
Narrow probe for boreholes and pump wells, on a vented cable.

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FAQ

What is a hydrostatic pressure transmitter?

A hydrostatic pressure transmitter measures the pressure created by a column of liquid and uses it to read level. Installed at the bottom of a tank, or lowered in as a probe, it senses the head of liquid above it and outputs a 4-20 mA or digital signal. Because the pressure rises in step with depth, that signal maps directly to how full the vessel is.

How do hydrostatic level transmitters work?

They rely on the rule that pressure at a given depth equals the liquid density times gravity times height (P = density x g x height). The transmitter reads the pressure at its diaphragm, and with the density known you convert it to level. An open tank needs a single measurement vented to atmosphere; a sealed or pressurised tank needs a second reference, or a differential type, so the gas pressure above the liquid cancels out.

What is the purpose of hydrostatic pressure?

In measurement terms, hydrostatic pressure is the useful signal. It is the pressure a still liquid exerts because of its own weight, and it grows with depth, which makes it a direct and reliable stand-in for level. From an instrument point of view the purpose is simple: by reading this pressure at one fixed point you know the height of liquid above it, with no float, beam, or moving part to wear.

Request a quote

Tell us the tank and we point you to the right model:

Maximum level and the liquid density or specific gravity
Medium (clean water, corrosive, slurry, hot)
Tank type (open, closed, pressurized) and mounting
Output (4–20 mA or digital) and cable length

Tell us the application and we configure one unit, not a shelf part. Not sure which type fits? Reach our application engineers.