For cryogenic systems, excellent liquid gas quality is essential; to ensure this, quality-enhancing products are often used. Examples, among others, are the phase separator and the subcooler. These products separate any gas bubbles from liquid gases in a cryogenic infrastructure to discharge them from the system or allow them to re-condense. As a result, the liquid gases remain pure and of high quality.
Quality improvement products, such as the phase separator and subcooler, always include a level sensor and a level controller. The level sensor measures the liquid level in the system. The level controller ensures that the sensor’s signal is converted into an action (for example, opening or closing a filling valve) or a high/low alarm.
Demaco supplies both the level sensor and the level controller. We also use a picostat (differential pressure sensor) and PT100/PT1000 (temperature sensors) to log liquid levels.
Demaco level sensor
The level sensor uses a capacitive measurement technique. It can sense the liquid level of almost all cryogenic boiling gases in a tank, dewar, or quality-enhancing product.
The sensor can operate stand-alone on a battery or be loop-powered connected to the level controller utilizing an analog 4-20mA signal. The sensor can be used up to an operating pressure of 35 bar. For flammable or hazardous gases such as oxygen, hydrogen, and LNG a special ATEX version is available.
The Demaco level controller
The Demaco level controller forms the link between the level sensor and the actual level in a quality-improving product. The handy controller compares the measured signal from the sensor with a preset value and opens or closes the filling valve at the precise moment.
Optionally the controller can be equipped with a PT100 overflow protector. The PT100 detects liquids in the blow-off line and triggers an alarm after which, for safety reasons, the supply is stopped.
The level controller is easy to mount, waterproof, and specially designed to regulate the liquid level in closed storage tanks, dewars, subcoolers, or phase separators.
Applications of the level sensor and level controller
The level sensor and level controller measure the level of liquid gases and are an integral part of quality improvement products. Industries where these products are often used include the medical industry, the food industry, the automotive industry, and the electronics industry. These industries mainly use nitrogen systems, in which temperature control and excellent quality liquid gas are essential for optimal operations.
The level sensor and level controller always form part of a cryogenic infrastructure. They complement quality-improving products, which in turn are connected to a vacuum-insulated piping system.