Siemens SITRANS FUP1010, Руководство по эксплуатации, Страница: 62 / 208

10.This time, before installing each sensor, apply a 3mm (1/8-inch) continuous bead of
couplant compound along the center (the long way) of the contact surface of the sensor.
Also, keep the sensors lifted slightly from the pipe when installing until the sensor is against
the pin; then push down against the pipe.
Note
Remember to install the sensors with the cable connectors facing away from each other.
11.Once the sensors are in place, secure with its clamping screws. Do not over tighten.
12.Observing the upstream and downstream orientation, attach the UP and DN cables to the
sensors and make snug. Attach the other ends to the UP and DN terminals of the flowmeter.
13.Proceed to Commissioning (Page 65).
5.3 Zero Flow Adjust Menu
Zero Flow Compensation Methods
Unlike turbine flowmeters ultrasonic transit-time flowmeters provide active flow measurement
right down to zero flow, however, the measurement of the transit-time delta is dependent on
the similarity or "match" of the electronics, cables and ultrasonic sensors. Consequently some
flow offset (or zero offset) may be present in any installation. To eliminate this residual zero
offset Siemens has developed several different methods to insure proper zero flow
compensation. The following paragraphs describe each method and when they should be used.
AutoZero
When the 1011HP sensors are mounted in the Reflect Mode configuration the AutoZero routine
is automatically invoked at the end of the Initial Makeup. Flow does not have to be stopped to
perform AutoZero since only the pipe wall signal is used in determining the zero offset and not
the liquid component. The AutoZero routine performs a one-time analysis of the pipe wall
component of the ultrasound signal to quantify any residual mismatch in the hardware. Once
the AutoZero routine is complete, the system memorizes this measured zero offset and
subtracts this value from the flow reading.
Actual Zero
The Actual Zero function simply averages the indicated "zero flow" readings (over a user
defined time period) then stores this average value in memory. Under normal operation the
indicated flow reading is zero compensated by simply subtracting this memorized value from
the uncompensated flow reading. Actual Zero is the most positive method for zeroing the
system; however, flow must be stopped with the line blocked (if possible) before invoking this
function. If stopping flow is not possible then an alternate zeroing method should be selected.
Connecting
5.3 Zero Flow Adjust Menu
FUP1010 IP67 Portable Flowmeter
60 Operating Instructions, 02/2010, A5E02951522A Revision 01