Greyline Instruments PDFM 5.1, User Manual

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Page 16
PDFM 5.1 Portable Doppler Flow Meter
SENSOR COUPLING
For permanent or temporary bonding, the following are recommended:
a) Dow Corning silicon compound #4 (supplied)
Additional supply: order Greyline Option CC
b) High Temperature compound
Additional supply: order Greyline Option AP-1W
c) Water-based sonic compound: Order Greyline Option CC30
d) Electrocardiograph gel
e) Petroleum gel (Vaseline)
The above are arranged in their order of preferred application.
d & e are only good for temporary bonding at room temperature.
DO NOT USE: Silicon RTV caulking compound (silicon rubber).
Use the PC4 pipe clamp (supplied) as illustrated above or
use a loop of electrical tape for temporary mounting. Apply
silicon coupling compound #4 to the coloured face of the
sensor. A bead, similar to toothpaste on a toothbrush, is
ideal. Do not overtighten (crush the sensor).
The sensor must be fixed securely to the pipe with coupling material
between the sensor face and the pipe. Sensor installation with
excessive coupling compound can result in gaps or voids in the
coupling and cause errors or loss of signal. Insufficient coupling
compound will create similar conditions.
Over time temporary coupling compounds (e.g. Petroleum Gel) may
gradually sag away from the sensor resulting in reduced signal strength and finally complete loss of
signal. Warm temperatures, moisture and vibration will accelerate this process. Dow Corning Silicone
Compound #4 as supplied with the PDFM 5.1 (and available from Greyline Instruments) is
recommended for semi-permanent installations.