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If the tester does not indicate flow:
Flowmeter
A)
Turn the selector switch to "INT". If the digital display is absent press the "ON" button. If
the display is still faint or absent check the condition of the battery and battery connections
located in the front panel of the DHT and in the side of the DHCR case. Replace battery if
necessary.
B)
If the flowmeter displays a valid temperature but no flow when in "INT" position it is likely
that the turbine has become jammed by debris. This usually consists of pieces of 'O' ring,
PTFE tape etc. Remove and clean turbine as in section D.
C)
If the flowmeter does not display flow when a remote flow block is connected, first ensure
that the unit is programmed with a Meter Factor (See programming section). Then check
all cable connections and finally the operation of the remote turbine as in section D.
D)
Turbine
To remove turbine assembly for cleaning, remove locking ring from inlet port, Fig. 1 hold
turbine flow straighteners with soft nose pliers and pull gently. Fig. 2 DO NOT ROTATE.
Remove debris and wash in clean organic solvent. Turbine should revolve freely when
blown along flow straightener.
Fig. 1
E)
Ensure the turbine block is also free of debris. Replace the turbine assembly ensuring the
clipped corner of the flow straightener is returned to the 1 o'clock position.
F)
The turbine can be driven with an air flow to check the flowmeter. For this test if a loading
valve is fitted it should be opened completely. Direct the air flow through the inlet port of
the turbine, switch on the tester to "INT". The air should rotate the turbine and the digital
display indicate the flow. If there is no reading check that the turbine is rotating. When
using compressed air, do not overspeed the turbine or the meter will be overloaded.
G) Cable/Hose Connections on the DHCR. Ensure that the cable and plugs are in good
condition and free from cuts. It is important that the connections on the flow block and
readout are correctly made. Note: ALWAYS disconnect the hose from flow block first or
oil leakage will occur. Ensure the plug on the flow block is correctly connected.
WARNING: Care should be taken while removing the turbine assembly. Damage to the
bearing will cause a loss of accuracy and the tester could malfunction.
For recalibration contact Webtec Products Ltd or your local sales office.
Service Instructions
13
Fig. 2
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