Xylem hydrovar - Page 65

65
S
0918
0918 OFFSET Y2
Desired value
0.00 PSI
Possible settings: 0 – standardization of the sensor
Desired value; designation of the y – coordinate as absolute value.
Example for using the Offset function:
Constant pressure system with required value of 70 PSI.
Additionally a ow sensor is connected to the Offset input.
Parameter [907] - Offset Range = 300 (maximum range of ow sensor = 70 GPM)
System requirement 1:
5 bar constant pressure while the ow rate is between 20 GPM and 50 GPM.
Below 20 GPM the pressure should be decreased to maximum 36 PSI at a ow rate of 8 GPM.
Settings:
Parameter [0910] - Level 1 = 50 = 20 GPM (rst limit where the offset function is active)
Parameter [0912] - Offset X1 = 20 = 8 GPM (xed point according the requirements)
Parameter [0913] - Offset Y1 = 2.5 = 36 PSI (max. allowed pressure at this ow rate)
System requirement 2:
70 PSI constant pressure while the ow rate is between 20 GPM and 50 GPM.
Above the 50 GPM the pressure should be increased with the limitation to have maximum 87 PSI at maxi-
mum ow rate of 16m³/h.
Settings:
Parameter [915] - Level 2 = 120 = 50 GPM (second limit where the offset function is active)
Parameter [917] - Offset X2 = 160 = 16m³/h (xed point according the requirements)
Parameter [918] - Offset Y2 = 6 = 87 PSI (required pressure at this ow rate)
PROGRAMMING
2 m
3
/h
5 m
3
/h 12 m
3
/h
OFFSET X2
OFFSET X1
OFFSET Y1
OFFSET Y2
Level 1 Level 2
Offset
020406080 100 120 140 160
0
2
4
6
8
10
12
14
16
Required Value
Required