Teledyne hfm-300 사용자 설명서

  

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y = 9.8877E-11x

3

3.4154E-07x - 

2

8.3288E-05x + 

-20.0%

-18.0%

-16.0%

-14.0%

-12.0%

-10.0%

-8.0%

-6.0%

-4.0%

-2.0%

0.0%

2.0%

0

100

200

300

400

500

600

700

800

900

1000

Turn the power supply on if not already energized.  Allow for a 1 hour 

warm-up.  Stop all flow through the instrument and wait 2 minutes.  
Caution:  Do not assume that all metering valves completely shut off 

the flow.  Even a slight leakage will cause an indication on the meter 
and an apparent zero shift.  For the standard 0-5 VDC output, adjust 

the zero potentiometer located on the inlet side of the flow meter 
until the meter indicates zero (Fig 2.3).  For the optional 4-20 mA 

output, adjust the zero potentiometer so that the meter indicates 
slightly more than 4 mA, i.e. 4.03 to 4.05 mA.  This slight positive 
adjustment ensures that the 4-20 mA current loop transmitter is not in 

the cut-off region.  The error induced by this adjustment is 
approximately 0.3% of full scale.  This zero should be checked 

periodically during normal operation.  Zero adjustment is required if 
there is a change in ambient temperature, or vertical orientation of 

the flow meter /controller. 

 

When operating at high pressure, the increased density of gas will cause natural convection to flow 
through the sensor tube if the instrument is not mounted in a level position.  This natural convection 

flow will be proportional to the system pressure.  This will be seen as a shift in the zero flow output 
that is directly proportional to the system pressure. 

 

 

Fig. 2.4 

Fig. 2.3