Emerson 00809-0100-4514 manual Correction For High Line Pressure Rosemount 1154DP and 1154HP Only

Rosemount 1154

Reference Manual

00809-0100-4514, Rev BA January 2008

Correction For High Line Pressure (Rosemount 1154DP and 1154HP Only)

The damping adjustment permits damping of rapid pressure variations by adjusting the single-turn trim potentiometer located on the upper right-hand side of the amplifier board (see Figure 3-4). The available settings, when adjusted to the maximum position, provide time-constant values of at least 1.2 seconds for Range Code 4 and 0.8 seconds for Range Codes 5–9 and 0. Transmitters with the electronic damping option are calibrated and shipped with the adjustment set at the counterclockwise stop, giving the minimum time-constant.

To adjust the damping, turn the damping adjustment potentiometer until the desired time-constant is obtained. It is best to set the damping to the shortest possible time-constant. Since transmitter calibration is not affected by the damping setting, you may adjust the damping with the transmitter installed on the process.

The damping adjustment potentiometer has positive stops at both ends. Forcing the potentiometer beyond the stops may cause permanent damage.

NOTE

If you remove either cover during the above procedures, replace the O-ring and torque the cover per the instructions given in Section 5 Maintenance and Troubleshooting of this manual. Spare cover O-rings are supplied with each transmitter.

Span

If a differential transmitter is calibrated with the low side at ambient pressure but will be used at high line pressure, correct the span adjustment to compensate for the effect of static pressure on the unit. If zero is elevated or suppressed, also correct the zero adjustment. Correction factors, expressed in percent of differential pressure input at end points per 1,000 psi static pressure, are:

Range Codes 4, 5, and 8:

+0.75% of input/1,000 psi

Range Codes 6 and 7:

+1.25% of input/1,000 psi

The correction procedure below uses the following example:

Range Code 5, calibrated at –100 to 300 inH2O, to be operated at 1,200 psi line pressure. Note that steps 3–6 are omitted for ranges based at zero differential pressure.

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