Operation, 5 function description – KROHNE BM 702 A EN User Manual

Page 40

OPERATION

BM 702 A

www.krohne.com

09/2009 - 4000643301 - MA BM 702 A R01 en

6.5 Function description

6.5.1 Tank height

The tank height (Fct. 3.1.1

Fct. 3.1.1

Fct. 3.1.1) is defined as the distance between the top edge of the tank

connecting flange and the bottom reference point. The bottom reference point is that "point" in
the tank on which the microwaves of the device hit and from which they are reflected. This may
be the tank bottom (symmetrical tank with flat bottom) or the non-horizontal part of the bottom
(e.g. tank with dished bottom) or an additionally fitted plate. The device cannot measure below
this point ("sump"in the tank).

6.5.2 Block distance

The "block distance" function (Fct. 3.1.2

Fct. 3.1.2

Fct. 3.1.2) defines a zone below the top reference point in which

measurements are not meant to take place. The value should be at least 10...20 cm / 3.9...7.9"
greater than the length of antenna + antenna extension, or at least 20 cm / 7.9" in the case of the
Wave-Stick.

Signals within the block distance are suppressed; a rise in the tank filling above this limit
(response threshold) will lead to a measuring result corresponding to a distance = block
distance, when Fct. 3.5.6

Fct. 3.5.6

Fct. 3.5.6 "BD Detection" is switched on.

6.5.3 Scaling of the current output

The scaling of the current output (Fct. 3.3.3

Fct. 3.3.3

Fct. 3.3.3: level 1 = 4 mA ; Fct. 3.3.4

Fct. 3.3.4

Fct. 3.3.4: level 2 = 20 mA) should if

possible lie within the measuring range (between bottom reference point and response
threshold).

By pressing the two upper keys (→ and ↑) or the two lower keys (^ and ↓) at the same time, the
0% setting (= 4 mA) or 100% setting (= 20 mA) can be programmed according to the actual level.

3.5.6

BD Detection

Select:

No / Yes

Yes

Switch the block distance (overfill)

identifier on/off. For detailed information

refer to

Function description on page 40.

3.5.7

Function FTB

Select:

Off

Off / Partial / Total

Select function of tank bottom tracing

system. For detailed information refer to

Function description on page 40.

3.5.8

Epsilon R

Enter:

1.1000...8.0000

Enter relative permittivity of product (only

for Fct. 3.5.7

Fct. 3.5.7

Fct. 3.5.7).

3.5.9

Tanktype

Select:

Storage Tank

Storage Tank / Process Tank

Select tank type.

"Storage Tank" = smooth product surface

"Process Tank" = slightly disturbed

product surface

INFORMATION!
When the tank is completely empty and the tank bottom provides good reflections (flat, not
dished bottom!), the tank height can also be automatically determined with the aid of Fct. 3.5.1

Fct. 3.5.1

"Auto Tankh.". Before confirming, check carefully that the proposed tank height is plausible!

.book Page 40 Thursday, September 3, 2009 2:53 PM