Mobrey ultrasonic liquid level detection systems ATEX
Mobrey ultrasonic liquid level detection systems ATEX
Mobrey ultrasonic liquid level detection systems ATEX
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System descriptionA <strong>Mobrey</strong> <strong>ultrasonic</strong> <strong>liquid</strong> <strong>level</strong>control comprises:• A tank mounted sensor containingtransmitter and receiver crystals• An RF sensor drive and detectorelectronic circuit, which may beintegral with the sensor or mountedadjacent to the sensor dependingupon vessel conditions or accessconsiderations.• A control unit mounted remotely tomonitor the sensor state and providethe required switching functionChoice of sensor<strong>Mobrey</strong> gap sensors<strong>Mobrey</strong> gap sensors energise a relayoutput when there is a <strong>liquid</strong> presentbetween the transmitter and receivercrystals of the sensor. In this way,absense of <strong>liquid</strong>, power failure ordamage to plant cabling will result inan alarm condition.Gap sensors are fail-safe low <strong>level</strong>.Typical applications• Pump protection• Vessel empty protection• Foam/froth <strong>detection</strong>• Pump control<strong>Mobrey</strong> Hi-sens sensors<strong>Mobrey</strong> Hi-sens sensors operate ina reverse manner. The transmitterand receiver crystals communicatearound the wall of the sensor whenit is dry. Presence of <strong>liquid</strong> aroundthe sensor damps out the 'ringing' ofthe sensor and an alarm condition isthen signalled.<strong>Mobrey</strong> Hi-sens is therefore failsafehigh <strong>level</strong> and will signal an alarmcondition on presence of <strong>liquid</strong>,power failure or damage to plantcabling.Typical applications• High <strong>level</strong> alarm• Overfill prevention• Leak <strong>detection</strong>Ultrasonic sensor operation can beadversely affected by the presenseof excessive aeration, solids orfoam in the <strong>liquid</strong>. If you have anapplication query contact <strong>Mobrey</strong> forexpert advice on the selection of asuitable <strong>liquid</strong> <strong>level</strong> <strong>detection</strong> systemSensors may be mounted in anyposition to signal <strong>liquid</strong> presence.Sensor with adjacent amplifierSensorwith headamplifier<strong>Mobrey</strong> gap sensor: General purpose failsafe low <strong>level</strong>b) Sensor in <strong>liquid</strong>The <strong>ultrasonic</strong> signalreaches receiver crystalTransmittercrystala) Sensor in airThe <strong>ultrasonic</strong> signal willnot reach receiver crystalReceivercrystalControl unitControl unit<strong>Mobrey</strong> hi-sens sensor (Models HL & HD): Fail safe high <strong>level</strong>a) Sensor in airThe <strong>ultrasonic</strong> signalreaches receiver crystalb) Sensor in <strong>liquid</strong>The <strong>ultrasonic</strong> signal is lost intothe <strong>liquid</strong> and does not reachreceiver crystalRelay output isenergised-NORMALSTATERelay output isde-energised-ALARM STATEControl unitControl unitControl roomelectronicsRelay outputis energised-NORMALSTATESignal is receivedRelay output isde-energised-ALARM STATENo signal is received
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