Mobrey

4 INSTALLATION4.1 PRELIMINARY CHECKSThe MSM400 system is normally supplied in two packages, one for the MSM400 Control Unit and one for thesensor, whether it is a pipe section or a tank sensor. Take care in handling the pipe section. In particular do notdamage the cable or the hose protection for the cable where it enters the sensors. Before installation check thatthere has been no damage in transit, particularly to the sensor cables. Check that the equipment is as specified, andthat the pipe section length and flanges are compatible with plant pipework.Sensors in intrinsically safe systems may be mounted in potentially explosive areas ("hazardous areas"). Refer to thesensor safety data section 2.4.The control unit must be mounted in a non-hazardous ("safe") area. Refer to control unit safety data section 3.3.4.2 PIPE SECTION INSTALLATIONThe Mobrey MSM448 pipe section sensor should be same size as surrounding pipe work. It should be installed in astraight section of line, if possible, with the sensors in a horizontal plane. This avoids the sensors being covered withdebris at the bottom of the pipe, and being in an air gap at the top of the pipe. Particular attention must be paid tothe positioning of the pipe section in relation to pressure reduction or agitation of the slurry to be monitored :Pipe lineSensors horizontal in pipe OKPipe lineSensors vertical in pipe NOT OKSludge settles on bottom sensorTop sensor probably in airFigure 7 : Pipe sensor orientationWARNING:Air or gas that comes out of suspension in a slurry gives a high ultrasonic attenuation, giving a false high solidsreading. The installation must maintain the full hydrostatic pressure in the slurry up to the pipe measurementsection. Any unnecessary pressure reduction should be avoided. This means avoid free fall of the slurry into a sump,avoid pumps and partly open valves, avoid abrupt changes of pipeline diameter upstream of the sensor pipe sectioninstallation point. If possible position the sensors directly at the outlet of the tank, low down, so that the fullhydrostatic head is maintained on the monitored liquid. However, it may be necessary to remove the sensors for facecleaning later, so isolation valves are desirable. The Mobrey Sensor pipe is supplied with a flushing spray nozzle,which directs a supply of water at the sensor faces. This is a useful cleaning procedure, avoiding the need to removethe sensors from the pipe. A water supply is required, connected to the purge nozzle on the top of the sensor pipesection.4.3 SUSPENDED SENSOR INSTALLATIONThe Mobrey MSM433 sensor is available with the gap between sensor faces from 100 mm up to 450 mm, for highersensitivity to light slurries. These sensors are usually mounted directly into the settlement tank, at pre-selected levelsabove the tank discharge outlet. Mounting can be vertically down on a piece of conduit, or suspended on the sensorcable. Whilst the conduit might be attached to the tank wall, it is normal to have the sensor well away from the wallitself, to avoid any non moving slurry or "dead" settlement areas. It should be possible to lift the sensor out forperiodic cleaning and/or rag removal.11IP258