GL-7B
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Catalog excerpts

CAPACITIVE Level switch The Kongsberg GL-7B level switch is specially designed for high level and overfill alarm detection in cargo tanks on chemical, oil product and LPG carriers. With continuous monitoring and no moving parts, this is a robust sensor that meets the IMO requirement concerning “Cargo Tank Overfill Protection System”. Application The GL-7B level switch can be used both with conducting and non-conducting liquids. The switch does not require any adjustment due to different types of cargo (liquid). Both single switch (one sensor-rod), and dual switch (two sensor-rods) are available. The sensor can be used in processes with temperatures down to -105 °C, suitable for vessels carrying LPG and LEG. The robust and smooth design with no moving parts is easy to maintain and clean, and can withstand powerful jetstreams from tank washing machines etc. inside tank. Functional Description The sensor uses a capacitive measuring principle for detecting level. The capacitance is measured between an inner and outer electrode. If a liquid enters the gap between the two electrodes, the capacitance is altered and this change in capacitance is used to detect liquid / no liquid. The sensor continuously monitor the capacitance, and therefore offers a self-monitoring feature. This measuring principle have been used by Kongsberg since 1979 and is a well proven, and often preferred, method for level detection on-board ships. Signal Interface The GL-7B level switch provides a two-wire 4-20 mA signal that gives a steady 8mA under normal condition. When alarm the signal rises to 12 mA. The built-in self-diagnostics provide default signal in case of contamination (21 mA) and in case of fault (3.6 mA). According to IMO requirements the sensor must be tested prior to loading. A functionality test of the switch and electronics is carried out by means of a small permanent magnet applied to the outside of the connection box. Installation The sensor is installed on tank top. The length of the sensor rods are custom made, typically to the level representing 95 % and 98 % volume of tank. The sensor connection box has a JIS B222 DN100 5K flange and is installed on adapter outside tank. If sensor rod exceeds 1.5 m, it is required to fasten the sensor rod in tank. This can either be done by a support to tank wall, or by finger-spring bracket inside an extended tank adapter. The latter must be specified before production of sensor. GL-7B is ATEX and IECEx approved as intrinsically safe equipment, and when installed in explosive area must be connected to barrier in safe are

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Order code TECHNICAL specifications General Power supply: Output signal: Weight: Material: Connection: Cable: Flange: 24 VDC (10 to 28 V) 4 to 20 mA with HART Normal = 8mA / Alarm > 12mA Depend on sensor length (i.e. 10 kg for 1 m double sensor) Rod: Acid resistant steel AISI316L Sensor element: PTFE or PEEK 2-wire 2.5 mm2 each sensor Ø6 - Ø20.5 mm2 JIS B222 100 5K Performance Accuracy: Environment Operating ambient temp.: Process temp.: Protection grade: Vibration: EMC: -45 to 85 °C (T4) / 70 °C (T5) -105 °C to 70 °C IP67 (housing) / IP68 (sensor) IACS E10 (max. 0.7 g) IACS E10 Approvals...

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