71
Reference Manual
00809-0100-4102, Rev AA
Section 5: Operation and Maintenance
May 2013
Operation and maintenance
Zero Effect:
± 0.1% of the upper range limit per 1000 psi (69 bar) for line pressures from 0 to 2000 psi (0 to
138 bar)
For line pressures above 2000 psi (138 bar), the zero effect error is ± 0.2% of the upper range
limit plus an additional ± 0.2% of upper range limit error for each 1000 psi (69 bar) of line
pressure above 2000 psi (138 bar).
Example: Line pressure is 3000 psi (3 kpsi). Zero effect error calculation:
± {0.2 + 0.2 x [3 kpsi - 2 kpsi]} = ± 0.4% of the upper range limit
Span Effect:
Correctable to ±0.2% of reading per 1000psi (69 bar) for line pressures from 0 to 3626 psi (0 to
250bar)
The systematic span shift caused by the application of static line pressure is -1.00% of reading
per 1000psi (69 bar) for Range 4 transmitters, and -1.25% of reading per 1000 psi (69 bar) for
Range5 tra nsmitters.
Use the following example to compute corrected input values.
Example
A transmitter with model number 2051_CD4 will be used in a differential pressure application
where the static line pressure is 1200psi (83 bar). The transmitter output is ranged with 4mA at
500inH2O (1,2 bar) and 20 mA at 1500 inH2O (3,7 bar).
To correct for systematic error caused by high static line pressure, first use the following
formulas to determine corrected values for the low trim and high trim.
LT = LRV + S x (LRV) x P HT = URV + S x (URV) x P
In this example:
Where: LT = Corrected Low Trim Value
LRV = Lower Range Value
S = –(Span shift per specification)
P = Static Line Pressure
Where: HT = Corrected High Trim Value
URV = Upper Range Value
S = –(Span shift per specification)
P = Static Line Pressure
URV = 1500inH2O (3.74 bar)
LRV = 500inH2O (1.25 bar)
P = 1200psi (82.74 bar)
S = ± 0.01/1000