Instruction manual

7532 Radar Tank Gauge

Varec, Inc. 13

4.3.2 Engineering hints

• The measuring range begins where the beam hits the tank bottom. Particularly with dish

bottoms or conical outlets the level cannot be detected below this point.

• For overspill protection, it is possible to define a safety distance (SD) additionally to the

blocking distance (BD).

• Depending on its consistence, foam can either absorb microwaves or reflect them off the

foam surface. Measurement is possible under certain conditions.

• The smallest possible measuring range B depends on the antenna version (see Fig.).

• The zero should be positioned at the end of the tube, as the electromagnetic waves do not

propagate completely outside the tube. It must be taken into account that the accuracy may

be reduced in the area C. In order to guarantee the required accuracy in these cases, it is

recommended to position the zero-point at a distance C above the tank bottom (see

Figure 4-3).

• In applications with planar antennas, especially for media with low dielectric constants

(media group A and B, (see Table 4-2 on page 14), the end of the measuring range should

not be closer than 1 m (40") to the flange (see A in Figure 4-3).

• The safety distance (SD) is set to 0.5 m (20") by default, generating an alarm in case the

product level rises inside the safety distance.

Figure 4-3: Measuring Conditions

Table 4-1: Reference Flange / Reference Antenna Tip

reference: flange / BD (see Figure 4-3) reference: antenna tip (see Figure 4-3)

Blocking distance Safety distance recommended additional settings

BD [m (ft)] SD [m (ft)] A [mm (in)] B [m (ft)] C [mm (in)]

7532 1 (3.28) 0.5 (1.6) 1000 (40) 0.5 (1.64) 150 to 300 (6 to 12)

100%

max. level