In cryogenic systems, the quality of liquid gas is crucial. To guarantee a high-quality liquid gas, the use of quality-enhancing products is common. Examples are the phase separator and the sub-cooler. These products extract and separate any gas bubbles which formed in a liquid gas in a cryogenic infrastructure. This results in the liquid gas remaining pure and of high quality.
Quality improvement products, such as the phase separator and sub-cooler, always include a level sensor and often a level controller. The level sensor measures how much gas has formed in the system, and the level controller ensures that this gas is adequately discharged.
Demaco supplies level sensors as well as level controllers. We also use a picostat (pressure difference sensors) and PT100/PT1000 to register a level.
The Demaco level sensor
The level sensor uses a capacitive measurement technique to detect the liquid level of almost all cryogenic boiling gases in a tank, dewar, or quality-enhancing system. The sensor can operate stand-alone with a battery or be loop-powered connected to a level controller using an analog 4-20mA signal. The sensor can be used with an operating pressure of up to 35 bar. A special ATEX version is available for combustible and flammable gases such as oxygen, hydrogen, and LNG.
The Demaco level controller
The Demaco level controller links the level sensor and the actual liquid gas level in a quality improving product. The controller compares the signal from the sensor with a pre-set value and opens and closes an exhaust valveat precisely the right moment. Optionally the controller can be equipped with a PT100 overflow protector. A PT100 detects any liquids in the discharge line and triggers an alarm signal, after which the supply is stopped for safety reasons. Depending on the required adjustments, the controller can be furnished with one or two regulators.
The level controller is easy to install, waterproof, and specially designed for regulating the liquid level in closed storage tanks, dewars, sub-coolers, or phase separators.
Applications of the level sensor and level controller
The level sensor and level controller assist in separating liquid gases; they form an integral part of the quality improvement products. Industries where these quality improvement products, including the level sensor and level controller, are commonly used are the medical industry, the food industry, the automotive industry, the pharmaceutical industry and the electronics industry. In particular, these industries use nitrogen systems in which both temperature control and an excellent quality liquid gas are crucial for reliable performance.
Level sensors and level controllers always form part of a cryogenic infrastructure. They complement quality-improving products, which are then, in turn, connected to a vacuum-insulated piping system.