Honeywell SLG 700 User Manual page 92

Probe Length:
The distance from the transmitter's Reference Plane to the end of the probe. This
parameter is normally entered by the factory based on the model number ordered and
does not need to be changed. See SLG 700 Transmitter User's manual #34-SL-25-11 for
trimming probes.
 For coax probes and rod probes without a centering disk the distance to
enter is the distance to the physical end of the probe.
 For rod probes with a centering disk attached the distance to the top surface
of the disk should be entered.
 For wire probes with an end-weight attached it should be the distance to the
top of the end weight.
Reference plane R
The GWR transmitter inherently measures the time of flight of radar pulses that reflect off the
boundary between two different mediums. This time is first transformed into a measure of the
distance between a fixed point on the transmitter body, referred to as the Reference Plane, and
the boundary between the two medium. The Reference Plane has been chosen to be a flat
machined surface near the probe connection point. Figure 12 shows the location of the Reference
Plane, denoted as R, for the two basic methods of connecting the transmitter to the tank, either
threaded or flanged. Refer to the Radar Level Measurement section in the SLG 700 Transmitter
User's manual #34-SL-25-11.
Figure 12: Reference plane R for flanged and threaded connections
Page 84
Flanged
SLG 700 Series HART Option User's Manual
Threaded
Revision 5