Honeywell SMV 3000 Flow calculation, Pressure reading, PV2 AP/GP or SP Range Values LRV and URV

6.7AP/GPConf Configuration - PV2, Continued

Background	Internally, the SMV transmitter uses absolute pressure values for all flow
	calculations. The value entered in the Atmospheric Offset field is added
	to the gauge pressure input value to approximate the absolute pressure.
	An inaccurate atmospheric pressure offset value will result in a small error
	of the flow calculation.
	Use an absolute pressure gauge to measure the correct atmospheric
	pressure. A standard barometer may not give an accurate absolute
	pressure reading.

PV2 (AP/GP or SP) Range Values (LRV and URV)

ATTENTION

The Lower Range Value and the Upper Range Value fields for PV2 are found on the AP/GPConf tab card.

Set the LRV (which is the process input for 0% output and URV (which is the process input for 100% output for the static pressure input PV2 by typing in the desired values on the SCT tab card.

•LRV = Type in the desired value (default = 0.0)

•URV = Type in the desired value

(default = 50 psia for model SMA110) (default = 750 psia for model SMA125) (default = 3000 psig for model SMG170)

NOTE: Static pressure may be absolute or gauge pressure, depending on the model SMV 3000 you have selected.

•The range for PV2 is static pressure (as measured at the high pressure port of the meter body).

•The URV changes automatically to compensate for any changes in the LRV and maintain the present span (URV – LRV).

•If you must change both the LRV and URV, always change LRV first.

Damping

Background

Adjust the damping time constant for Static Pressure (PV2) to reduce the output noise. We suggest that you set the damping to the smallest value that is reasonable for the process. The damping values (in seconds) for

PV2 are:0.00d, 0.16, 0.32, 0.48,

1.0, 2.0, 4.0, 8.0, 16.0, and 32.0

d Factory setting.

The electrical noise effect on the output signal is partially related to the turndown ratio of the transmitter. As the turndown ratio increases, the peak-to-peak noise on the output signal increases. See the Damping paragraphs in subsection 6.6 for a formula to find the turndown ratio using the pressure range information for your transmitter.

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