Honeywell 854 ATG Series User Manual

Commissioning
Instruction manual 854 ATG Page 25
3.4.4 Interface measurement
Interface 3 (I3) is used as product / water interface measurement (with interface 2 (I2) another interface can
be measured). The set point S3 has to be set to such a value that half of the displacer volume is immersed in
the water and the other half of the displacer volume is immersed in the product.
That can be calculated as follows (refer to figure 3.9 and to Appendix B for detailed displacer information):
S3 = DW - (½ DV x ρ
product
+ ½ DV x ρ
water
) [g]
w
here:
S3 : set point I3 measurement [g]
DW : displacer weight [g]
DV : displacer volume [cm
3
]
ρ
product
: density of the product [g/cm
3
]
ρ
water
: density of water [g/cm
3
]
Example:
Displacer #0815.343 : ø45 mm
Displacer weight (DW) : 223 g
Displacer volume (DV) : 105 cm
3
Volume lower conical part : 3.2 cm
3
Figure 3.9 Calculation of set point
Height lower conical part : 6 mm
Density product : 0.9 g/cm
3
S3 = 223 - (52.5 x 0.9 + 52.5 x 1) = 123.25 [g]
A level offset must be given as the displacer is now immersed for half of the volume in water. On product
level the displacer is immersed less. The difference between both immersion depths must be given in item L3
Example:
1) Immersion depth on product level surface:
displaced volume : (DW - S1)/ρ
product
= 15/0.9 = 16.67 cm
3
v
olume in cylindrical part : 16.67 - 3.2 = 13.47 cm
3
immersion of cylindrical part : 13.47/πr
2
= 13.47/(π x 2.25
2
) = 0.85 cm = 8.5 mm
immersion depth on product : 8.5 + 6 = 14.5 mm
2) Separation line product / water :
water volume in cylindrical part : ½DV - 3.2 = 52.5 - 3.2 = 49.3 cm
3
water height in cylindrical part : 49.3/πr
2
= 49.3/(π x 2.25
2
) = 3.1 cm = 31 mm
separation line product / water : 31 + 6 = 37 mm (from lower end of displacer)
Hence, level offset L3 becomes : 37 - 14.5 = 22.5 [mm]
Item Name Description
W2= Protection level 2 Enter protection level 2 password
S3= Set point I3 Standard floating point format; units: grams.
Set point for the product / water interface measurement.
L3= Level offset I3 Format according to item LD.
Level offset between interface 1 immersion depth (where the gauge is
calibrated) and the product / water interface immersion depth.
EX Exit Exit protection level

Honeywell 854 ATG Series Specifications

General

Brand	Honeywell
Model	854 ATG Series
Category	Measuring Instruments
Language	English