14
Service Instructions
If the tester does not indicate flow:
FLOWMETER
A)
Turn the Tester “ON”. 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 DHC
case. Replace battery if necessary.
B)
If the flowmeter displays a valid temperature but no flow 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 C
C)
TURBINE
To remove turbine assembly for cleaning, remove circlip 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.
D)
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.
E)
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. 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.
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.
Fig. 1
Fig. 2
