Series 810 Instruction Manual
Chapter 4 Maintenance
If your unit is experiencing one of the other symptoms listed above,
remove the small front access door to expose the test points, pots
and DIP switches. (see figure 3.1)
TESTPOINT BLOCK (labeled TP in Figure 3.1):
Setpoint
TP10
*
* TP9
Valve +
+5V Reference
TP8
*
* TP7
4-20mA out
0-5 volt out
TP6
*
* TP5
Common
Bias Voltage
TP4
*
* TP3
Test Flow Signal
Sensor Amp
TP2
*
* TP1
Bridge Voltage
Caution!
It is important that
only qualified
personnel calibrated
this transducer.
1.
Connect a voltmeter to test points 9 (Valve +) and 5 (Common) and set
the scale for 30 volts or higher.
2.
Apply two set points, one at 5% full scale and then one at 100% full
scale — either locally or remotely (be sure the dip switches are in the
proper positions). Monitor the valve voltage at each point. The
acceptable range for the valve voltage is 6 to 18 VDC over these two set
points.
3.
If the valve voltage is outside of these specifications, loosen the 5/16"
lock nut, and adjust the center adjustment screw. Turning clockwise
will increase the valve voltage, while turning counterclockwise will
decrease it. Adjust slowly, 1/8 turn at a time while monitoring valve
performance. When the desired voltage is obtained, the symptoms
should disappear and the lock nut can be re-tightened.
4.
Re-install the front access door and conduct a final check for leak-by
with a zero set point, paying particular attention to the seal on the
adjusting screw. Remember to monitor pressure decay only, as liquid
leak detectors may damage the instrument.
If these adjustments do not restore proper performance to your Mass-Trak,
contact Sierra Instruments' Technical Support Department.
Transducer Calibration
Calibration of Sierra's flow meters and controllers requires a calibration
standard of at least equal accuracy and preferably an order of magnitude
IM-81
4-5
