Instruction manual

Startup
continued
RFT9739 Rack-Mount Transmitter Instruction Manual 65
Output Wiring Startup TroubleshootingBefore You Begin Getting Started Mounting
Power-Supply and
Sensor Wiring
6.4 Flowmeter zeroing
Flowmeter zeroing establishes flowmeter response to zero flow and sets
a baseline for flow measurement.
Zeroing procedure
To zero the transmitter, follow these steps:
1. Prepare the flowmeter for zeroing:
a. Install the sensor according to the sensor instruction manual.
b. Apply power to the transmitter, then allow it to warm up for at least
30 minutes.
c. Ensure the transmitter is in a security mode that allows flowmeter
zeroing. See "Security modes", page 6.
d. Run the process fluid to be measured through the sensor until the
sensor temperature reading approximates the normal process
operating temperature.
2. Close the shutoff valve downstream from the sensor.
3. Ensure zero flow through the sensor.
4. Zero the transmitter in any of four ways:
• Press and hold the Reset button for at least ten seconds. (In the rate
screens, "RATE" appears in the upper left corner of the screen.)
• An external contact closure can be used for transmitter zeroing.
(Refer to
Section 5.8
, page 54, for wiring instructions). Close the
contact for at least ten seconds.
• Issue an auto zero command using a HART Communicator, a
HART-compatible or Modbus-compatible master controller, or the
ProLink program.
• Issue a "zero trim" command with the AMS program.
CAUTION
Failure to zero the flowmeter at initial startup could
cause measurement error.
Zero the flowmeter before putting it in operation.
CAUTION
Flow through the sensor during flowmeter zeroing will
result in an inaccurate zero setting.
Make sure the sensor tubes are
completely
full and fluid
flow through the sensor is
completely
stopped during
flowmeter zeroing.