Switches Indicators & Gauges

Hydrostatic Pressure

Hydrostatic pressure is the pressure at any given point in a static fluid. Pressure in open conditions (e.g. the ocean, the atmosphere, a pond) can be approximated as the pressure in static conditions, since the motion of currents or waves create only negligible changes in pressure. It is the same at any given point because otherwise the fluid would move in the direction of the resulting force.

According to the principles of equilibrium, the pressure of a liquid at rest is isotropic, meaning it acts with equal magnitude in all directions. If a point in the fluid is thought of as an infinitesimally small cube, the pressure of every side of this unit of fluid must be equal. This characteristic allows fluid to transmit force through the length of pipes (a closed condition).

Hydrostatic pressure is useful for determining the levels of liquid in a tank, among other things, using devices such as a hydrostatic tank gauge.

Hydrostatic Bubbler

Semrad Pty Ltd offers a range of industrial level gauges, sensors, switches and transmitters. Their WaterLOG® H-3531 FlashLite™ is a NIST traceable pressure sensor. It combines low cost with high accuracy, as it can directly measure dry gas with accuracy better than 0.02% FSO. It comes with built-in temperature compensation, with an operating range between -40° and +60°C.

This non-submersible pressure sensor has an easy to use Simple RS-232 Menu Interface, and a non-conductive and corrosion proof enclosure. Its SDI-12 output provides measurement data in engineering units (e.g. feet or meters), it is easy to use with the H-355 Gas Purge System and is compatible with the RS-232 Data Logger. It also features extended SDI-12 command for setting the stage to the correct water elevation or pressure. It operates on low currents and deviates less than 0.02% from a staight line referenced to end points.

What are Gas Bubbler Systems?

One type of basic gas bubbler system is a glass bulb containing a small amount of fluid, with the inlet to the bulb connected to a ground glass joint and the outlet vented to the air. They are used in laboratories to exclude air from a reaction, or to prevent air contaminating a system. In the first case, the gas bubbler is fitted on the condenser of the reaction set-up. In the latter, an oil bubbler is installed at the end of the inert gas manifold on a Schlenk line. The schlenk line is a chemistry apparatus used for manipulating air sensitive compounds. Gas bubblers act as a one-way valve, where gasa bubble through the fluid before being vented. In this way, if there is a lack of pressure some fluid is sucked intoa sump to equalise it rather than air.

In a purge gas pressure monitoring system, a piezometer tube runs from a pressure measuring instrument into a medium to be monitored. A piezometer is an instrument for measuring pressure, especially very high pressure, or for measuring the compressibility of materials under pressure. Purge gas is carried to the tube to escape as bubbles as the end of the tube are submnerged in the medium. The pressure of gas escaping from the tube relates to the pressure of the medium into which it is bubbled. This is then measured and the data is send to a data recorder.

WATERLOG® H-355 ‘Smart-Gas’ System

The Waterlog ‘Smart-Gas’ system is a reliable, light weight and low power unit suitable for use in the most remote locations. The automatic bubbler system can replace nitrogen tanks, oil sight feeds, flow regulators and leaky manifolds that are heavy and dangerous.

This systems is a complete single unit replacement that can be used at a depth of up to 115ft, uses no mercury with selectable flow rates, and controlled or automatic purge functions.