Teledyne HASTINGS 200 - Manual (Page 13)

126B - PAGE 13
4.0 MAINTENANCE
4.1 Introduction: 4.1 Introduction: 4.1 Introduction: 4.1 Introduction: 4.1 Introduction:
This section contains service and calibration information. Some portions of the instrument are delicate.
Use extreme care when servicing the flowmeter. The potentiometer positions and the electrical compo-
nents referred to in the troubleshooting section can be found in Section 6.0 on the electrical component
layout drawing.
4.2 4.2 4.2 4.2 4.2 Author Author Author Author Authorized Maintenance: ized Maintenance: ized Maintenance: ized Maintenance: ized Maintenance:
With proper care in installation and use, the flowmeter will require little or no maintenance. If mainte-
nance does become necessary, most of the instrument can be cleaned or repaired in the field. Some
procedures may require recalibration. Do not attempt these procedures unless facilities are available.
Entry into the sensor or tampering with the printed circuit board will void warranty. Do not perform
repairs on these assemblies while unit is still under warranty.
4.3 4.3 4.3 4.3 4.3 Adjustments: Adjustments: Adjustments: Adjustments: Adjustments:
4.3.1 Calibration Procedure 4.3.1 Calibration Procedure 4.3.1 Calibration Procedure 4.3.1 Calibration Procedure 4.3.1 Calibration Procedure
1. 1. 1. 1. 1. Connect power cable to D connector as specified in Section 2.5. Allow instrument to warm up for
30 minutes with all flow shut off.
2. 2. 2. 2. 2. Set ZERO potentiometer for 0.000 VDC output at pin 6 on the D connector or flow output pin on
the rear of the Hastings Power Supply.
3. 3. 3. 3. 3. Turn on air supply to inlet of instrument. Adjust flow rate to 100% according to flow reference.
4. 4. 4. 4. 4. Adjust SPAN pot until the flowmeter
indicates full scale flow (5.000 VDC).
NOTE: Perform this step only if a
calibrated reference flowmeter is avail-
able.
5. 5. 5. 5. 5. Record flowmeter and flow reference
outputs for flow rates of 20%, 40%, 60%,
80%, and 100%.
4.3.2 Response 4.3.2 Response 4.3.2 Response 4.3.2 Response 4.3.2 Response Time Time Time Time Time Adjustments Adjustments Adjustments Adjustments Adjustments
Readjustments of the fast response
circuit should not be necessary unless
changes in the range or sensor have
been performed. The flowmeter should
be calibrated before setting the response
time.
IMPORTANT: Response time cannot
be tested with a simple shutoff valve.
Pressure builds up behind the valve, and when opened creates a surge flow in excess of the calibrated flow rate.
What must be used is a two-way valve or a fitting which can be quickly connected and provide a leak-free seal to
the flowmeter inlet. The reference flow is vented to atmosphere, and switches through the flowmeter when the
valve is operated or fitting is connected. The valve or fitting should be close coupled to the flowmeter inlet to
reduce pneumatic time delays. The response pot is not accessible from the exterior of the flowmeter. The cover
must be removed to make any adjustments. See Fig.
4.1.
Using a voltmeter, strip chart recorder, or oscilloscope connected to the flow output voltage, switch flow through
the flowmeter and observe output voltage. Adjust response pot to increase or decrease response time. The
response pot is a single turn pot and a small pot adjustment produces a large response time change. Remove flow
from flowmeter and allow output voltage to reach zero volts. Repeat test until response time is set.
4.3.3 4.3.3 4.3.3 4.3.3 4.3.3 Miscellaneous Miscellaneous Miscellaneous Miscellaneous Miscellaneous Adjustments Adjustments Adjustments Adjustments Adjustments
Periodically, during normal operation, the ZERO should be checked and adjusted when required.
Fig.4.1 Fig.4.1 Fig.4.1 Fig.4.1 Fig.4.1