Toshiba LF494 - Manual (Page 32)

TOSHIBA
6 F 8 A 0 7 7 4 .
62 Zero Adjustment
To conduct zero adjustment of the flowmeter, the fluid in ihc detector pipe must be held stilL
There are three different ways to start the ^ero adjusimeni:
(
1
) I^essingthe zero adjustment switch for the model without IX^D display
(2) Pressing a combination of control keys for the model with LCD display
(sec 8.2.8, ‘Zero Adjustment ’)
(2) Sending a command signal from a HAR'l’ communications device
(such as the AFIOO hand-held terminal).
The follow'ing is the procedure for starting the zero adjustment for the model without LCD
display.
■ J’ress the zero adjustment switch for more than 3 seconds.
(Note [hat once the zero adjustment is started, there is no way to caitceJ the zero
adjuslmem sequence.)
Then the LHD indicator lights and [he zero adjustment sequence will start. 1 he zero
adjustment sequence lasts about 3 to
6
seconds. (Zero adjusimcrit duration depends on
the excitation current frequency. Jl lakes about 3 seconds for 24 Hz setting and about
6
seconds for 12 Hz and
6
Hz settings.)
When the zero adjustment sequence ends, the LliD indicator goes off.
To conduct the zero adjustment, it is necessary to open the converter housing cover for
inicmaJ electronics and press the switch. Observe the following precautions when you
open the hou.sittg cover:
(1) Do not open the cover in the open air unprotected against rain or wind.
It you adjvist the ilowiucier in the rain, this can cau^e electric shock or damage to the
flowmeicr electronics. If wind blows against the internal circuitry of the converter, output
may fluctuate and fail to indicate correct measuring values.
(2) l>o not conduct the zero adjustment when the amhieni humidity is high, By opening the
cover in high humidity conditions, the measuring accuracy may he reduced or damage
caused to the flowmeter electronics.
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