Fluid Components International MT86_MT86HT Manual Operation - Manual (Page 5)

Doc. No. 003162 Rev. F 3 - 5 Models MT86, MT86HT
CHAPTER 3 - OPERATION FLUID COMPONENTS INTL
New Calibration Procedure (in field)
Note: The flowmeter is calibrated for use with specific customer applications and flow ranges. There may be
cause in the field to readjust the calibration to meet the field data or applications.
A flowmeter EPROM stores data to accommodate a range expansion of up to 25% above full range. If any changes
are performed a new Delta "R" table will be needed to represent the adjustment. If an output adjustment is made,
properly record the data and make it available for FCI records.
The flowmeter has a method for changing the span and zero adjustment in the field without losing the original factory
setting. The factory set span and zero will have jumpers J1, J5 and J7 installed, see Figure 5-3 for the electrical
assembly layout. FCI recommends that after any adjustment are made to the output, a new Delta "R" table should
also be made. Once an adjustment is made the original Delta "R" table does not represent the changes made.
Span Adjustment Only
The true flow rate of the process flow and the indicating milliamp output of the flowmeter need to be known before
going on with the following adjustment procedure. Record and have the information available for FCI to review.
The flow rate should be above 60% of full scale to justify a span adjustment only. Do not perform a span adjustment
if the data obtained is at a flow rate below 40%.
The following procedure is for sensing point (head) number one (1), but any sensing point can be used. The sensing
point number that is selected must match the head number selected at the head-selector, switch SW2.
1. Record the true flow of the process media and the flowmeter's milliamp output.
2. Turn the operating power OFF.
3. Connect the FC81 Field Calibrator to sensing point number 1. A set of precision decade boxes can be used
instead of an FC81 Field Calibrator. For the decade box wiring diagram refer to Figure 5-4.
Model FC81-8 is used for the MT86 with 1000 ohm flow element sensing point RTDs.
Model FC81-7 is used for the MT86HT with 100 ohm flow element sensing point RTDs.
4. Close switch SW1-3 that puts the flow transmitter in the manual mode; this enables the head-select switch SW2
to select and monitor one sensing point. Turn ON the operating power.
5. Adjust the FC81 Field Calibrator, or precision decade boxes, to give the milliamp output that was recorded in
Step 1. Record the Delta "R" that produced this output.
6. Remove jumpers J1 and J7. Add jumpers J2 and J8. This makes the span circuitry active.
7. With the FC81 Field Calibrator still at the Delta "R" from Step 5, adjust the span potentiometer, R16, to the new
output as calculated from the true flow measurement in Step 1.
8. From the Delta "R" table, put in the Delta "R" resistance value that represents the 4.0 milliamp output. Verify
that the output has not been affected by the span adjustment.
9. Turn OFF the operating power. Open switch SW1-3, and position the head-select switch SW2 to the number of
sensing points in the system. This puts the flowmeter back in the operation mode.
10. Remove the FC81 Field Calibrator or decade boxes and connect sensing point number 1 to the input board.
Span and Zero Adjustment
As with the span adjustment, field data is also needed to perform adjustments. The information that is needed is the
true flow rate and the indicating milliamp output of the flowmeter. Record and have the information available for
FCI to review. The procedure is basically the same as the span adjustment procedure. See Table 3-1 for jumper
positions.