Open Vessel Level Measurement Calculation
a) Example calculation for the transmitter installed in zero-based direct mount application
The Calibration Range may be computed using the following method:
At zero percentage of level (for 4mA output)
Pressure = 1.1 X 0 (head level is 0”)
At 4 mA = 0”H2O
At 100 percentage of level (for 20mA output)
Pressure = 1.1 X 80”(head level is 80”)
At 20mA= 88 ”H2O
The calibration range of the transmitter is = 0 to 88”H2O(4 to 20mA)
b) Example calculation for the transmitter installed in non- zero-based direct mount application
The Calibration Range may be computed using the following method:
At zero percentage of level (for 4mA output)
Pressure = Head1
= 1.1 X 10”
At 4 mA = 11”H2O
At 100 percentage of level (for 20mA output)
pressure = Head2
= 1.1 x 70”
At 20 mA = 77 ”H2O
So the calibration range of the transmitter is = 11’’H2O to 77”H2O(4 to 20mA)
c) Example calculation for the transmitter installed in non- zero-based remote mount application
The Calibration Range may be computed using the following method:
At zero percentage of level (for 4mA output)
Pressure = Head1
= 1.1 X 10”
At 4 mA= 11”H2O
At 100 percentage of level (for 20mA output)
Pressure = Head1 + Head2
= (1.1 X 10”) + (1.1 X 80”)
=11” + 88’’
At 20 mA= 99 ”H2O
So the calibration range of the transmitter is = 11’’H2O to 99”H2O(4 to 20mA)
Closed Vessel Level Measurement Calculation
Closed Tank Level Calculation with Wet Leg
a) Example calculation for the transmitter installed in zero based direct mount application
The Calibration Range for the DP transmitter is calculated as like below
At zero percentage of level (for 4mA output)
Differential pressure = Phigh – Plow
= 0 – Head1
= 0 – (1.1 X 80”)
At 4 mA= -88”H2O
At 100 percentage of level (for 20mA output)
Differential pressure = Phigh – Plow
= Head2 – Head1
= (1.1 X 60”)] – (1.1 x 80”)
=66-88
At 20 mA = -22”H2O
Cal. Range = -88 to -22”H2O(4 to 20mA)
b) Example calculation for the transmitter installed in non zero based direct mount application,
The Calibration Range for the DP transmitter is calculated as like below
At zero percentage of level (for 4mA output)
DP = Phigh – Plow
= Head2 – Head1
= (1.1 X 10”) – (1.1 X 80”)
=11” – 88”
At 4 mA = -77”H2O
At 100 percentage of level (for 20mA output)
DP = Phigh – Plow
= (Head2 + Head3) – Head1
= [(1.1 X 10”) + (1.1 X 50”)] – (1.1 X 80”)
=11”+55”-88”
At 20 mA = -22”H2O
Cal. Range = -77 to -22”H2O(4 to 20mA)
c) Example calculation for the transmitter installed in non zero based remote mount application
The Calibration Range for the DP transmitter is calculated as like below
At zero percentage of level (for 4mA output)
DP = Phigh – Plow
= Head2 – Head1
= (1.1 X 10”) – (1.1 X 90”)
=11” – 99”
At 4 mA = -88”H2O(LRV)
At 100 percentage of level (for 20mA output)
DP = Phigh – Plow
= (Head2 + Head3) – Head1
= [(1.1 X 10”) + (1.1 X 60”)] – (1.1 X 90”)
=11”+66”- 99”
At 20 mA = -22”H2O(URV)
Cal. Range = -88 to -22”H2O(4 to 20mA)
