Yamatake Corporation Operation of the Transmitter
ST3000 Smart Transmitter Series 900 Electronic Differential Pressure/Pressure Transmitter 5-53
Set range calculation Ex. STE/STR Type
Calculate the set range using these procedures:
The following symbols are used to express density and distance.
It is assumed that the density is fixed, during liquid level measurement.
: Specific gravity of liquid in tank
: Specific gravity of sealed liquid
l : Distance between 100% liquid level and 0% liquid level (measurement range)
h : Distance between 0% liquid level and high-pressure outlet port
d : Distance between high-pressure outlet port and transmitter
Figure 5-11 Open Tank
Differential pressure at 0% liquid level (Pressure on high-pressure side - Pressure on
low-pressure side) = hr = LRV
Differential pressure at 100% liquid level (Pressure on high-pressure side - Pressure
on low-pressure side) = l + h = (l+h) = URV
Therefore, set the range as follows:
Low limit (LRV): h ; High limit (URV): (l+h) r
Example of calculation:
l = 1500 mm, h = 250 mm, d = 500 mm, = 0.9, = 0.935
If the above conditions are assumed, the following results are obtained:
Differential pressure at 0% liquid level = 250 x 0.9= 225 mmH
2
O = 2.206 kPa
Differential pressure at 100% liquid level = (1500 + 250) x 0.9 = 1575 mmH
2
O =
15.45 kPa
Therefore, set the range as follows:
Low limit (LRV): 2.206 kPa, High limit (URV): 15.45 kPa
ρ
ρ
0
d
h
ρ
ρ
0
100% liquid level
Open tank
0% liquid level
High-pressure
side
Low-pressure
side
ρρ ρ
ρ
ρρ
0
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