Technical specification sheet
IP201 February 2007 Level Mobrey ultrasonic liquid level detection systems
Features
No moving parts Simple installation ATEX Hazardous area approval Ignores foams Unaffected by: RF Interference Conductivity Droplets Most coatings Liquid colour/opacity Description
Ultrasonic liquid level switches are for use in industrial process, nuclear and marine cargo applications to detect high or low liquid levels. Operation is achieved using the time proven principle of ultrasonic transmission between two crystals. Liquid presence is detected by virtue of its bulk, with liquid droplets, condensation or foaming being ignored. Mobrey Hi-sens sensors are designed for fail-safe high level duty. Mobrey gap sensors are designed for fail-safe low level duty. Control electronics are available standard or self-checking, with options including lamps to indicate sensor status, time delays and circuits to detect wiring faults. Mobrey has been manufacturing and selling high quality ultrasonic level equipment for many years, and have built up considerable expertise in the supply of non-catalogue equipment, custom designing system if the standard product will not meet the exact application requirements. Typical applications
Petroleum processing Fuels, lubricating oils, hydraulic fluids, liquid petroleum derivatives, crude oil, fuel - water interfaces. Chemical processing Acids, alkalis, ammonia, paints, lacquer, waxes, peroxides, alcohols, slurries, printing inks, freon. Food processing Beverages, fruit juices, cooking oils, molasses, liquids with entrained solids. Pharmaceutical and cosmetic Liquids, emulsions, lotions, solutions. Marine operation Fuel oil, hydraulic fluid, bilge level alarms, sea water, coolant, condensate levels, cargo levels. Reactor operation Level control, alarm signalling. Cryogenic liquids Liquid methane, nitrogen, oxygen, etc. Water industry Flood control, reservoir levels, sludge blanket detection, sewage sump control. General Leak detection, overflow alarm, low level alarm in evaporation ATEX System description
A Mobrey ultrasonic liquid level control comprises: · A tank mounted sensor containing transmitter and receiver crystals · An RF sensor drive and detector electronic circuit, which may be integral with the sensor or mounted adjacent to the sensor depending upon vessel conditions or access considerations. · A control unit mounted remotely to monitor the sensor state and provide the required switching function Sensor with adjacent amplifier Sensor with head amplifier Control room electronics Mobrey gap sensor: General purpose failsafe low level b) Sensor in liquid The ultrasonic signal reaches receiver crystal Control unit Relay output is energisedNORMAL STATE Choice of sensor
Mobrey gap sensors Mobrey gap sensors energise a relay output when there is a liquid present between the transmitter and receiver crystals of the sensor. In this way, absense of liquid, power failure or damage to plant cabling will result in an alarm condition. Gap sensors are fail-safe low level. Typical applications · Pump protection · Vessel empty protection · Foam/froth detection · Pump control Mobrey Hi-sens sensors Mobrey Hi-sens sensors operate in a reverse manner. The transmitter and receiver crystals communicate around the wall of the sensor when it is dry. Presence of liquid around the sensor damps out the 'ringing' of the sensor and an alarm condition is then signalled. Mobrey Hi-sens is therefore failsafe high level and will signal an alarm condition on presence of liquid, power failure or damage to plant cabling. Typical applications · High level alarm · Overfill prevention · Leak detection Ultrasonic sensor operation can be adversely affected by the presense of excessive aeration, solids or foam in the liquid. If you have an application query contact Mobrey for expert advice on the selection of a suitable liquid level detection system Sensors may be mounted in any position to signal liquid presence. Signal is received Transmitter crystal Receiver crystal Control unit Relay output is de-energisedALARM STATE No signal is received a) Sensor in air The ultrasonic signal will not reach receiver crystal Mobrey hi-sens sensor (Models HL & HD): Fail safe high level a) Sensor in air The ultrasonic signal Relay output is reaches receiver crystal energisedNORMAL STATE Control unit b) Sensor in liquid The ultrasonic signal is lost into the liquid and does not reach receiver crystal Relay output is de-energisedALARM STATE Control unit Choice of system & control unit
Select from the systems below the one which meets your needs, then fold out page 6 and select a sensor to suit the liquid in the vessel. Standard industrial
Industrial control unit
MCU control box Co-axial cable Supply Hi-sens sensor Co-axial cable Supply Gap sensor Relay Relay High integrity
Electrosensor
MES control box Electropulse
wire twisted pair MEP control box Supply Supply Relay MEP rack control wire twisted pair SAFE HAZARDOUS SAFE Failsafe wire twisted pair Relay Safe area use only · Wall mounting IP65 polycarbonate enclosure · Connection between sensor and control unit is by up to 50m of dual co-axial cable · Failure of sensor or breakage of coaxial cable earth loop will cause an alarm condition and light the fault LED. Intrinsically safe ATEX II 1 G EExia IIC T4 · Cabinet or DIN rail mounting control unit · Simple twisted pair cable between sensor and control unit up to 000m · Safe or hazardous area use · Failure of sensor or cabling will cause an alarm condition and light the fault LED Additional fault relay activated on fault condition Intrinsically safe ATEX II 1 G EExia IIC T4 · Cabinet, DIN rail, or rack mounting control unit · Simple twisted pair cable between sensor and control unit up to500m · Safe or hazardous area use · Any failure of the sensor, electronics or associated wiring causes the system to give alarm and fault outputs · Fitted with test switch to simulate alarm and fault conditions Description The MCU00 control unit provides simple, economical control electronics for mounting on site near the tanks containing the appropriate ultrasonic sensor. The sensors provide liquid level detection and are available in various materials and mechanical designs. The control unit has a sensitivity potentiometer to adjust for sensor and liquid type. MCU 00 offers in addition a selectable time delay, earth continuity checking between sensor and control unit, and LED's to indicate sensor state. MCU 00 has a DPCO relay output and is suitable for use with all Mobrey sensors. Select sensor: Fold out page 6 Technical data: Pages 4-7 Control electronics: Page 8 Description Mobrey Electrosensor systems provide a cost effective method of level detection and control where high system integrity coupled with low cost installation is required. Ultrasonic sensors are fitted with head-mounted or adjacent electronics which are then connected back to control room electronics using simple twisted pair wiring Sensors may be set to operate either when wet or dry and have a field adjustable sensitivity potentiometer and status LED. All sensors are built to IS standards and may be used in safe or hazardous areas. Select sensor: Fold out page 6 Technical data: Pages 4-7 Control electronics: Pages 9- Description Designed and developed to provide the ultimate fail safe system. Electropulse electronics can be used with most Mobrey sensors. Head mounted or adjacent electronics communicate with control room electronics by sending pulses down simple twisted pair wiring. Electropulse systems are specified in applications where level is of critical importance, such as marine tanker overfilling, chemical plant and nuclear plant. Sensors may be set to operate either when wet or dry and have a field adjustable sensitivity potentiometer and status LED. All sensors are built to IS standards for use in safe or hazardous areas. Select sensor: Fold out page 6 Technical data: Pages 4-7 Control electronics: Pages -5
Ultrasonic point level sensors : Dimensions
WH shows approimate switching level with sensor horizontal WV shows approximate switching level with sensor vertical Extended length versions: Max A = 000mm vertical, 95mm horizontal, where A is the measurement from the mounting thread run-out to the nominal switching point. General purpose
Sensor type 332 SD General purpose stainless steel Design or duty: Liquid type: Temperature: Standard Clean only -70oC to +50oC Sensor type 302 SD General purpose stainless steel Design or duty: Liquid type: Temperature: Standard Clean, minor aeration -70oC to +50oC
¾" BSPT 85 9 7 WV 8.5 0 0 7 4 7 Ø WH " BSPT Ø6 0 WV WH 6 0 0 WH 80 WV Sensor type 312 S* High sensitivity plastic Design or duty: Liquid type: Temp. PP: PPS: Plastic Aerated -70oC to +65oC -70oC to +0oC 6 Ø8 " BSPT WH7 ¾" BSPT WV 0 0 A 4 Sensor type 312 SY High sensitivity epoxy Design or duty: Liquid type: Temperature: resin Aerated liquids Clean, aerated -70oC to +0oC Sensor type 323 SY Wide gap epoxy resin & stainless steel Design or duty: Dirty liquids Liquid type: Clean, aerated, viscous with scale, with solids Temperature: -70oC to +0oC Sensor type 393 SD High sensitivity stainless steel Design or duty: Dirty liquids Liquid type: Clean, aerated, viscous with scale, with solids Temperature: -70oC to +50oC 0 0 5 5 WV 0 7 WH 9 " BSPT WV 0 Transducer epoxy 6 5 WV 7 WH Clearance dia min 75 Ø5 8 ¾" BSPT 66 40 99 7 0 ¾" BSPT For 9SE specify this dimension 'A' 0 5 WH 9 " BSPT 5 8 WH Sensor type HL General purpose stainless steel Design or duty: High level Liquid type: Clean, aerated, with solids Temperature: -70oC to +0oC Multipoint sensors Maximum length 000mm Typically used for two level pump control or combined high and low level alarms. Mounting flanges optional to order Model HD 2 Point maximum Model 5S 2 Point maximum Model 7S 6 Point maximum ¾" BSPT ¾" BSPT 0 0 Optional flange 0 0
DCBA A (59 min) 47 WV A (59 min) WV Ø49 Ø49 Ø49 B (59 min) WV WV 0 ¾" BSPT Min 7 Max 000 Min 7 Min 5 Min 7 Max 455 Ø 7 WV 4 Ultrasonic point level sensors : Dimensions Low temperature
Sensor type 362 SJ Epoxy & stainless steel Design or duty: Liquid type: Temperature: Cryogenic small Clean, aerated, with solids -0oC to +65oC High temperature
Sensor type 30 HS High temperature stainless steel Design or duty: Liquid type: Temperature: High temp. Clean, aerated, with solids +oC to +50oC Sensor type 39 HS High temperature stainless steel Design or duty: Liquid type: Temperature: High temp. Aerated, viscous with solid scale +oC to +50oC 0 9 64 4 WH 40 9 49WV 66 ½" BSPT ¾" BSPT 6 80 ¾" BSPT
0 0 9 A WV 6 0 5 0 0 WV ¾" BSPT Clearance dia. min. 85 9 8 WH 9 Ø WH Ø 6 ¾" BSPT 9 4 Mounts from outside vessel Note: temperature at point of cable exit from sensor must be less than 50oC Mounts from outside vessel Note: temperature at point of cable exit from sensor must be less than 50oC Chemical duty
Sensor type 389 ST PTFE for chemical applications Design or duty: Liquid type: Temperature: PTFE body Clean, aerated -0oC to +0oC Miniature sensor
Sensor type 366 SJ Miniature Design or duty: Liquid type: Temperature: Small space Clean -0oC to +65oC Across pipe sensor
Sensor type 442 SD Across pipe Design or duty: Liquid type: Temperature: Pipelines Clean or may be used for sludge detection -70oC to +50oC ½" # 50 range Ø7 Stainless steel PTFE wetside wv This diameter corresponds to flange face Ø4 A = (9mm min) Ø48 Ø40 Ø9.5 M6 thread 9 Carbon or stainless steel flange "#50 or NW50 ND0 60 Ø40 BA/F WV 4 WH 6 Ø 79 5 0 0 PTFE wetside ¾" BSPT WH Note: Max. pressure 0 bar (Extended length models .75 Small space model with low thermal capacity .5 bar max. pressure High pressure
Sensor type 422 SD Stainless steel Design or duty: Liquid type: Temperature: High pressure Clean -70oC to +50oC Interface
Sensor type 433 SD Stainless steel Design or duty: Liquid type: Temperature:
0 6 6 Ø WH 6 0 0 5 ¾" BSPT 58 5 6 Ø WH 0 Specify gap 50 to 450mm 0 ¾" BSPT WV WH Sensor type 402 SD Stainless steel Sludge or interface Viscous or with solids in suspension -70oC to +50oC Design or duty: Liquid type: Temperature: Chemical interface Clean, viscous with solids -70oC to +50oC 69 0 0 5 ¾" BSPT WV 0 Standard gap = 50mm For non-penetration, interface & sludge sensors, see pages 6 & 7 5 Sensor technical data
Standard sensors Repeatability (mm) Max. pressure (d) (bar) Weight (gm) Standard frequency (MHz) 302 30H 312 (352) 39H SU SR 05 50 0 50 .5 312 SY 5 50 323 332 362 389 393 402 422 (373) (366) 5 70 .5 56 00 05 50 .7 433 442 621 HL3 601 (HD) 5 500 50 See p.6 50 400 50 500 .7 80 05 05 N/A 00 50 50 850 50 600 .7 .7 .7 .7 Technical data for all sensors · Sensors are fitted with meters cable and appropriate glands to fit control box. · Power consumption is less than 0 milli-watts at sensor. · Cable entry to sensor is IP65. · MTBF of stainless sensors is found to be 0.5 x 0.6/hr. · Temperature shock range - 70°C to + 0°C if applicable. · Mechanical shock - all transducers tested to withstand 0G min.. · Non operational temperature limit 75°C typical. Sensor cable · Standard is P.T.F.E. insulated dual coaxial with PVC sheath. · Minimum bend radius is 5mm. · Radiation resistant cable, suitable for 00 Mega rads, may be supplied to order. Non-catalogue sensors Many of our customers have particular applications for which we custom engineer and build sensors. Whatever your requirement for a level control sensor, if you can not find a suitable model in this catalogue, please do not hesitate to contact Mobrey for further discussion. Non-penetration liquid level sensors
Type 621 · No contact with liquid · No penetration of vessel · For 8 to 75mm OD pipes Description The 6S ultrasonic liquid level sensor is mounted outside the sight glass or pipe to be monitored, at the required switch position. The two parts of the sensor are accurately aligned on site on either side of the pipe. Using epoxy resin or silicone grease, the ultrasonic signal is coupled into and through the pipe wall into the liquid or gas within the pipe. Liquid allows transmission to the opposite wall and through to the other part of the sensor. The sensors are connected to a adjacent head amplifier unit, to provide a liquid presence relay output. Technical data Repeatability: Typically mm depends on Model numbers Pipe size: Models are available to suit most pipe outside diameters within the range 8mm to 75mm. Accurate sizing is important to ensure reliable operation state with order the tube or pipe outside diameter for each application. Typical installation 5.9 4. 58.7 Head electronics Receiver 60. application Housing: Epoxy resin Temperature: -0oC to +0oC Cable: m PTFE coaxial cable Adhesive bond: Epoxy resin pack supplied with every sensor pair Mounting: Horizontal preferred Transmitter 6 Interface detection and sludge measurement
Ultrasonic technology can be used to discriminate between immiscible liquids, to indicate the interface and to detect and monitor suspended solids. Interface detection For interface detection between immiscible liquids, two techniques are available: ultrasonic attenuation and ultrasonic reflection. Both techniques use standard Mobrey liquid level control electronic systems. Suitable sensors for interface monitoring, are typically the larger gap types, that is 50mm upwards. Interface detection by attenuation
Sensor in oil The ultrasonic beam is attenuated and will not reach the receiver crystal Air Oil liquid is in the gap. The ultrasonic attenuation of a liquid depends on many factors, the main ones being the complexity of the molecule, followed by the viscosity, assuming there is no aeration. Many liquids can be distinguished by this technique and for further information on previously tested liquid systems consult our technical sales. If samples of the liquids are available then a simple site test can often be done. Interface detection by reflection
Air Oil Water Head electronics Head electronics Air Head electronics Transmitter crystal Receiver crystal Sensor in water The ultrasonic beam reaches the receiver crystal Oil Water Oil Water Head electronics Transmitter crystal Receiver crystal Ultrasonic attenuation is the reduction in energy of the beam as it is transmitted through the liquid. Viscous liquids, emulsions and liquids with entrained solids generally have a higher ultrasonic attenuation than low viscosity clear liquids such as water. When the attenuation difference is sufficient, the amplifier gain can be adjusted so that the ultrasound beam passes through the less attenuative liquid but is stopped by the more attenuative liquid. The output relay can then be set to monitor which Special sensors Special combinations of sensors are produced for specific applications - e.g. combined sludge blanket detectors, pump controls and very high level alarms. Such combinations are designed and engineered for each individual application, whether for shipboard high level alarms, waste processing plants or reservoir control systems. Contact the sales office for further information. Multipoint sensors Ultrasonic sensors are easily combined into multi-point transducers for two level pump control or combined high and low level alarms. When two immiscible liquids have similar attenuations the above method cannot be used, however it is likely that the velocity of ultrasound will be different. In this case a beam of ultrasound passing through the interface will be reflected and refracted and if the sensor is arranged at a shallow angle the effect is that the transmitted beam tends to miss the receiver and is thus effectively attenuated. An angle of 0 degrees is chosen and often this results in total internal reflection of the transmitted beam. Thus when the interface is within the gap of the angled sensor, Typical standard sensors are: Model HD - A two point dual high level sensor using two Hi-sens HL sensors. This is typically used for 95% and 98% high level alarm on marine cargo tankers, for outline dimensions see page 9. Model 373 - A multipoint version of the 9 sensors, with up to 6 switching levels. Fitting: ¾" BSPT from inside the vessel. Option: flanged to customer specification Model 352 - Two point version of the 0 type sensor, fitted from inside or outside of vessel very little ultrasound reaches the receiver, but when the interface is above or below the sensor (ie in either liquid) then there is a large signal present. The control unit gain is set to actuate the relay when the interface is in the gap. Note this condition will also occur if the upper liquid drains away and air (gas) is in the gap. Note for further information on suitability of this application consult our technical sales. Suspended solids measurement Solids suspended in a liquid will scatter ultrasonic beams, causing attenuation. This attenuation depends on the size and nature of the particles and for typical sewage sludges it is possible to use Mobrey ultrasonic systems to detect % to 5% w/w. Industrial slurries such as fine pottery slips can often be measured to 65%, but coarse granular material is often very attenuative. Leaflet IP50 gives details of Mobrey sludge measurement systems. Interface and sludge monitoring Typically sensors with gaps of 50mm or larger are used for interface and sludge measurement. These sensors are standard types 40, 4 and the 44 (a pair of sensors for mounting across or along a pipe section). Special flanged sensors with the 0 degree tilt built in are also available. Generally these sensors work at .7MHz and are compatible with Electropulse and Electrosensor electronics or plant mounted MCU00 electronics. DCBA Multipoint & special combination sensors Min 7 Min 5 Clearance dia. min. 75 Min ¾" BSPT B A Min 7 Max 000 Min 7 Max 455 7 7 Mobrey standard industrial control unit MCU00
· Simple economical control unit · IP65 enclosure · 5v/0v AC or 4v DC · Features: Sensor status LED Time delay Cable check Pump control MCU control box Co-axial cable Supply Hi-sens sensor Relay Co-axial cable Supply Relay Gap sensor Safe area use only Description The MCU00 control unit provides simple, economical control electronics for mounting on site near the tanks containing the appropriate ultrasonic sensor. The sensors provide liquid level detection, and are available in various materials and mechanical designs. (See fold out page 6). The control uni provides a relay output for external control or alarm functions according to whether the sensor is wet or dry. The MCU 00 has a dual pole relay output energised when the sensor is wet, LED indicators, time delays and cable check facilities preselectable. The MCU00 will operate with all Mobrey ultrasonic sensors and can accept a voltage free contact input from another level switch to give a pump control function on the output relay. Installation Mobrey ultrasonic sensors are normally fitted with metres of dual coaxial cable. This cable can be extended with suitable coaxial extensions up to 50 metres. Suitable cable is part No. K78, or two lengths of coax type RG78 can be used. The coaxial cables are terminated in the control unit. The output cabling from the control unit comes from the relay output terminals as a wet/dry changeover switch. This can be used to trigger an alarm or provide an input into a control system. Power supply (Selector switch) Power consumption Relay output Relay rating Box dimensions Box rating Holes for glands Fixing centres (WxH) Fixing hole diameter MCU201 110/120V ac 220/240V ac MCU203 24V ac TBA DPCO 5A at 0V 00 x 0 x 75 IP65 Polycarbonate off 6mm dia, 88 x 88 4mm Technical data MCU200 Features Suitable for all Mobrey ultrasonic point sensors Frequency selection by switch on PC board. Relay Energised for sensor wet or dry selectable by switch. LED indicators Visible through the box lid. Green for normal. Red for alarm. Selectable for wet/dry sensor as appropriate for the application. Amber LED for fault condition. Gain potentiometer Fitted with scale and separate range switch to adjust for sensor type and site conditions. Response time Selectable delay of 0.5, , 8 or 0 seconds. Delay selectable wet to dry or dry to wet. 50 ms response in opposite direction. Sensor cable check Selectable to monitor coax screen to sensor for continuity. Fault lights fault LED and sets relay to alarm state. Auxiliary input External closed circuit input to MCU 00 latches the output relay to achieve pump control. The MCU00 product range generally replaces control units types T96 & T496 8 Electrosensor systems
Description An Electrosensor system comprises an ultrasonic sensor with associated 'head' electronics, are either mounted directly on the sensor or in an adjacent wall mounting Control room electronics · Provides intrinsically safe power supply to sensor electronics and detects sensor state. · Operates output relays and front panel LEDs · Monitors plant wiring integrity Principle of operation The twisted pair supplies a DC voltage from the control electronics to the sensor. The current drawn by the sensor is used to signal the sensor state. This current signalling is detected by a trip amplifier in the control electronics. The control electronics include a fault monitoring circuit to detect if the current drawn is outside preset limits, such as would occur on cable breakage or short circuit. Electrosensor can be used in all areas of the plant. Some users may prefer to provide their own supply and alarm circuits. Electrosensors are fully system certified to accommodate this need, enabling connection to PLC or other control circuits via standard Zener safety barriers when the sensor is in a hazardous area. Specification ATEX
box, and control room electronics. Connection between sensor electronics and control electronics is by standard twisted pair instrument cable, typically over distances of up to 000m.
MESL/*S control room unit MESD/S control room unit (External barrier required) Ordering information MESL/S: 0V ac MESL/S: 5V ac Current 0 6 mA Oscillating 8 4 0 Nonoscillating Ordering information MESD/S: 4V dc FAULT WET DRY FAULT Common specifications Design concept Will de-energise relay on loop current levels falling outside of preset limits (i.e. open or short circuit) All control room electronics have visible LEDs to indicate sensor and fault detection circuit status. LED indicators (3) Alarm relay on, Alarm relay off, fault detected Approval ATEX II()G [EExia] IIC (MESD/S requires separate external safety barriers ATEX II () G for connection to the sensor in a hazardous area.) Stand alone electronics: MES3L/*S Operates one electrosensor or two sensors for pump control Alarm relay output Selectable: energised for sensor wet or sensor dry using PCB switch. When two sensors are connected, relay assumes a pump control function and PCB switch now selects whether the relay is energised to fill or empty the tank between the two sensors. Fault relay output De-energises on fault condition. PCB switch to select whether the fault condition also de-energises the alarm output relay. Relays (2) SPCO 00V A max/ 5 A max. Cable entry Via base cutouts through rubber grommets to terminal strip. Voltage MES*L/S: 0V ac 50/60Hz MES*L/S: 5V ac 50/60Hz Output to sensor Mains powered units: v DC intrinsically safe, fully floating (galvanically isolated) Delay 0.5s wet to dry 50ms dry to wet Ambient temp 60oC Power consumption 8VA Protection IP0 Power supply tol. AC mains +/- 0% DIN rail electronics: MES2D/3S Operates one electrosensor and is suitable for cabinet mounting on standard DIN rail. includes fault monitoring to detect abnormal current level and operate alarm relay. Alarm relay output Selectable: energised for sensor wet or sensor dry using PCB switch. Rating: SPCO 00VA max/ 5 A max Time delay Adjustable 0.5 to 0s either wet to dry or dry to wet. Connections Terminal strip. Voltage 4V dc: 0-0V Output to sensor 4v dc powered units: 4V dc fully floating (galvanically isolated). External zener barriers required when sensor in hazardous area (refer to system certificate)
9 Electrosensor head electronics
Most of the sensors on pages 4-5 can be specified with Electrosensor electronics. MHz sensors with dual screwed fittngs can be specified with head mounted electronics housed in a tough nylon enclosure integral with the sensor. A field adjustable gain potentiometer and an LED indicator, visible through the end cover to show sensor status are provided. A selector switch to set the 6mA signal to occur either with the sensor wet or dry is also provided. A terminal with PNP output allows direct connection to a PLC input via a third signal wire. Sensor head electronics are also available in an adjacent wall mounting enclosure, for use with any MHz or .7MHz sensor. These elecronics are used where it is not possible or desirable to mount the electronics directly on the sensor. Connections between adjacent electronics and sensor is by dual coaxial cable (maximum length 0m). Head electronics Adjacent electronics: MESAI The Electrosensor model no. as selected from page 6 includes head electronics, code SSH. Suitable sensor must be selected from page 6 code U8H only Head mounted (integral) electronics Mounted in a tough glass filled nylon enclosure weatherproof to IP66/IP67 the head electronics drive the sensor and detect its state; either wet or dry. Connection is via the M6 cable gland (supplied). Removal of the housing cover reveals: · Adjustable gain potentiometer to set the sensor to suit application conditions. · Mode selector switch. · Connections for control electronics. · LED to indicate sensor state (visible through window in end cover) Adjacent mounted electronics The sensor drive and detector electronics are enclosed in a wall mounted IP65 polycarbonate box which is wired to the sensor using dual co-axial cable (maximum length 0m). Connection is via M6 cable glands (supplied). Removal of the box lid reveals: · Sensor frequency selector switch (Mhz or .7Mhz) · Coarse and fine grain adjustment to set the sensor to suit application conditions. · Mode selector switch. · Connections for sensor and control electronics. · Output selector switch for 8-6mA current loop operation. If PLC operation is selected, current drawn is set to approximately 8mA in both sensor states (wet or dry). · LED to indicate sensor state (visible only when box lid removed). Specification
Hazardous area or approval Electrosensors are approved intrinsically safe ATEX II G EExia IIC T4 (-40°C < Ta < +85°C) T5 (-40°C < Ta < +40°C) and can be used with control room electronics (Page 9) or used in an intrisically safe system. Power input: -4V DC from associated MES control room electronics or other suitably protected source. Sensing: Draws either 8 or 6mA on a current loop dependent upon sensor state and mode switch setting. Mode selector Gives choice of current level for sensor state. Would typically be set for 6mA with sensor switch oscillating (i.e gap sensor wet, Hi-sens dry) Output selection Both types of head amplifier have a transistor output on a third terminal, suitable for signalling to a PLC or similar device. This transistor output switches upto 0mA at the supply line voltage onto the third wire. Ambient temp. - 40°C to + 60°C Earthing Head electronics are floating with respect to sensor body. Sensor body may be earthed through tank connection. Plant cabling Standard twisted pair instrument cable recommended with screen (screen not connected at head electronics). Maximum loop resistance 0 ohms. Cable parameters must conform to ATEX requirements. Users own Electrosensors on this page can be used in any intrinsically safe system. electronics The user must ensure that suitable safety barriers are used.
0 Electrosensor ordering information
MESL control room electronics Electrosensor fitted with head amplifier MESD control room electronics Electrosensor with adjacent amplifier Customers own control electronics Zener safety barriers HAZARDOUS AREA Ordering information - control room electronics MES Mobrey Code 3 2 Electrosensor Approvals Intrinsically safe (type L enclosure only) Non I S Code Enclosure D DIN rail enclosure (requires external safety barriers for IS use) L Stand alone enclosure Code Voltage input 1 0V ac MESL only 2 5V ac MESL only 3 4V dc (non I S) Code Relay output S SPCO SAFE AREA
MES
3
L /
1
S Typical model number Ordering information - control room electronics Sensor Head amplifier Fold out page 6 MESAI Select type ***SDU8H* Ordering information - control room electronics Sensor/amplifier Fold out page 6 Select type ***SDSSH* Section 5 - Electropulse systems
wire twisted pair MEP control box Supply Relay MEP rack control wire twisted pair HAZARDOUS SAFE Electropulse systems provide the ultimate in fail safe liquid level alarm. Standard sensors are fitted with a head amplifier which communicates with a control room unit using standard twisted pair instrument wire. Using a gap sensor for low level and a Hi-Sens for high level, a system is constructed such that any failure: mechanical, electronic or in the communication line, causes the system to fail safe. Electropulse control room mounted elecronics provide front panel LED indication of the level sensor status, plus a change-over relay output, rated at over 500VA, to control pumps, alarms or signal to the controller. The green LED labelled "NORMAL" indicates that the sensor is in its oscillating condition. For all gap sensors the oscillating condition is the wet condition, for Hi-Sens sensors this is dry (see over). The red LED indicates that the sensor is not oscillating, which is defined as "Alarm". A further LED, yellow, indicates a "Fault" condition, resulting from plant cabling faults or head amplifier damage to either of these causes the current in the control loop to deviate from normal value. The fault condition automatically triggers the alarm relay and the red alarm LED. The Electropulse MEPR units are cards suitable for mounting in the standard 9" MEPB rack, up to 4 units per rack. These MEPR cards are available with either SPCO or DPCO alarm relay and a separate SPCO fault relay. The Electropulse MEPL units are single units housed in a plastic case, suitable for wall, panel or DIN rail mounting.. These units are only available with one combined DPCO alarm/fault relay. For hazardous area operation the MEPR and MEPL units have intrinsically safe sensor output connections. When used with the appropriate sensor, the system is approved intrinsically safe to ATEX standards. Plant cabling The Electropulse control room readout units are connected by a twisted pair instrument cable, preferably screened, to the Electropulse head amplifier. This twisted pair provides approximately Volt DC at 5mA to power the head amplifier and sensor: current pulses of mA at approximately 40Hz signal that the sensor is in the oscillating or NORMAL state. The ALARM state is indicated by constant current drain. Loop resistant of the two wire cable must be less than 5 ohms. The audio current signalling provides a noise and RF interference resisitant transmission over long distances. Head amplifier Electropulse head amplifiers provide the necessary interface between the ultrasonic liquid level sensor and the control room electronics. The head amplifier is either mounted directly onto the sensor or is mounted on the plant close to the sensor. The head amplifier is a tuned RF amplifier at either MHz or .7 MHz to suit the sensor. When the attentuation between transmitter and receiver piezoelectric crystals is low enough, the amplifier oscillates. This is the NORMAL or oscillating condition of the sensor. The oscillation frequency is divided down by normal digital circuitry until a square wave at around 40 Hz is obtained. This is used to switch the mA current drain on and off across the supply line from the control unit. Head amplifiers are available in IP66/IP67 aluminium housings and IP68 gunmental housings when mounted on the sensor and in an IP65 polycarbonate box for plant mounting adjacent to the sensor. Optionally available, a push to test switch on the head amplifier allows an operator to simulate alarm conditions, for shutdown testing. Other options include two separate head amplifiers in one IP68 housing, and stainless steel housing material. "Normal" sensor state For gap sensors, the NORMAL condition occurs when the sensor is immersed in liquid. Hi-Sens sensors oscillate and give NORMAL indications when the sensor is in air, dry. The NORMAL condition with an active oscillating sensor is the best state for a level alarm system, since all components are energised and active. Such a system is 'fail safe'. System selection Mobrey sensor head (see pages 4, 5 & 6) Control room mounted separate control Direct mounting head amplifier or Co-axial cable connection to Twisted pair instrument cable or See page 5 See page 4 IP66/IP67 or IP68 Adjacent mounting Rack mounted Electropulse card IP65 Relay output An Electrosensor system comprises three modules:Liquid sensor: Fold out page 6 and select the most appropriate sensor for your application. (For adjacent mount electronics see Page 7 Descriptions are given on page 5 - choose wall/DIN rail mounting or rack mounting. Ordering information is given on page 7 Control room electronics: Typical system (Direct mounting head amplifier): Liquid sensor: Control room electronics: 0SDPIH MEPR/S Typical system (Adjacent mounting amplifier): Liquid sensor: Adjacent amplifier: Control room electronics: SU U8H MEPAI/CPN MEPR/S Elecropulse sensor head amplifier units 0mm 0mm 1. Industrial sensor head mounted amplifier unit The head amlifier is mounted on the sensor in an IP65 (IP66/IP67 when suitably glanded) aluminium die cast box. Cable connection via one or two PG6 gland holes. Sensor gain potentiometer adjustable and gain switch accessible with lid removed. 2. Marine sensor head mounted amplifier unit The head amplifier housing in either gunmental or stainless steel is permanently mounted on the sensor flange. Cable connection is via one of the M0 gland holes, into cable clamp and corrosion resistant terminals. Amplifier board is coated with polyurethane varnish and is optionally resin potted. Lid is 'O' - ring sealed. Gain control adjustment potentionmeter is factory preset, but site adjustable. For use with two point sensor two totally separated head amplifiers can be housed in one MARINE housing. The general design concept of the marine sensor head amplifier is based on the worst case of deck mounting on a chemical tanker. Typical application involves two Hi-Sens sensors positioned for 95% and 98% high level alarms. 3. Adjacent sensor head amplifier Housing polycarbonate box designed for mounting adjacent to the sensor. Sensor coaxial cables are attached to terminals in the housing, and the twisted pair plant cable fits through an M6 plastic gland. Gain switch and adjustment potentiometer are accessible with the lid removed. Reverse action unit With standard head amplifiers as above, the "NORMAL" condition on control room readout unit occurs when the liquid sensor is in its active/ oscillating condition. (Gap sensor wet, Hi-Sens sensor dry). Model MEPXI reverse acting amplifier (in the adjacent amplifier type housing) reverses this head amplifier logic, pulses are signalled on the line and "normal" readout is indicated in the MEPL or MEPR when the sensor is not oscillating (Gap sensor dry, HiSens sensor wet). Common specifications
Function The head amplifier provides the RF drive circuitry for the liquid level sensors (gap type or Hi-Sens) or for interface detection sensors. These sensors are physically attached to the head amplifier, or mounted very close to the adjacent amplifier. Signals are transmitted along the two wire plant cabling to Electropulse control room units to provide readout. Design concept - fail safety The head amplifier electronic design features fail to safety (no pulse output) for any anticipated electronic, mechanical or wiring failure. Hazardous area approval Units are available approved intrinsically safe to ATEX, EN5004, EN5000. Certified IIG EExia IIC T4. (-40°C