Emerson Process Management manual Installation, Location of the MSP900SH transmitter

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Installation, Operation & Maintenance Manual

IP2040/IM, Rev. AA

May 2007

MSP900SH

 

 

3.0Installation

The MSP900SH may be mounted in a hazardous area provided it is supplied through or from a suitably protected power supply (such as the Mobrey Measurement MCU900 Series).

Refer to the safety parameters given in section 2.2 and safety instruction leaflet IP2040/SI (-A), 71097/1131 (-U).

3.1Location of the MSP900SH transmitter

The transmitter must be installed in a location where it is protected from ultraviolet radiation, in order to prevent long term degradation of the plastics used in its construction e.g. shrouded from direct sunlight.

Correct location of the transmitter is essential for the reliable operation of any ultrasonic level measurement system. Whilst the transmitter may be site tuned to deal with most application conditions, it is strongly recommended that the following guidelines should be adopted wherever relevant.

For maximum accuracy and stability of the level measurement reading the transmitter should always be shrouded from direct sunlight and any radiated heat.

The transmitter should be mounted as near vertical as possible to ensure a good echo from the liquid surface and maximum echo size received. The beam angle (to the half power point) of the transmitter is 12 degrees inclusive.

If the transmitter is located near the side of the tank or well, there will be no false echo generated provided the wall is smooth and free of protrusions.

However, there will still be a reduction in the echo size. To avoid large echo size loss, it is recommended that the transmitter never be mounted closer than 300mm to the wall.

Fatty, dirty or viscous liquids can cause a “scum line” to build-up on the tank or well wall. Avoid false echoes from this by enabling “scum line prevention” software in the MCU control unit.

If the transmitter is mounted in an enclosed tank, avoid mounting the transmitter in the centre of the tank roof as this could act as a parabolic reflector and create unwanted echoes.

If the transmitter is mounted in a stand-off or nozzle, it is always preferable that the transmitter face be at least 5mm proud of the stand-off such that it protrudes beyond the stand-off and into the tank.

Remember that the minimum operating range of the transmitter is 300mm. The transmitter will not detect any liquid surface closer than 300mm to the transmitter face.

Obstructions in the tank or well may generate echoes which can be confused with the real liquid surface echo. Obstructions within the beam angle generate strong “false-echoes”; wherever possible, the transmitter should be positioned such that false echoes are avoided.

To avoid detecting unwanted objects in the tank or well, it is advisable to maintain a distance of at least 0.11m from the centre line of the transmitter for every metre range to the obstruction.

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Contents Mobrey Contents Type numbering system IntroductionMSP900SH ultrasonic level transmitter Pressure Equipment Directive Safety DataSpecifications Location of the MSP900SH transmitter InstallationGeneral considerations Open Channel Flow installationsLiquid surface conditions In-tank / well effectsHmax Important Never suspend the transmitter by the cable WiringMounting the transmitter above the liquid surface Lightning / surge protection and other loop devices Wiring to allow Hart communicationMaintenance Hart programming of the MSP900SH transmitter Commissioning / Programming Current OutputHead Verification Device Accessories Submersion shieldAppendix I MSP900SH programming parameters = 3.9 Range of 4-20mA signal Appendix Intrinsically safe control drawing Abcdef