Electronic Flow Sensing

Designating gas type

Designating gas type

To scale the displayed flow rate value properly, one of four commonly used gases must be designated. The appropriate gas type is selected according to Table 4•1:

Table 4-1. Defining Type of Gas to be Monitored

Number

Gas Type

Preferred Use

 

 

 

1

He (Helium)

TCD

2

N2

(Nitrogen)

General

3

H2

(Hydrogen)

Capillary

4

Ar/CH4 (Methane in Argon)

ECD

To select one of these gases for a particular flow channel, press:

 

FLOW

(

B )

to display FLOW A (or FLOW B).

1 ,

2 ,

3

, or

4 is then pressed, followed by ENTER . Upon pressing

ENTER

, the current flow rate is displayed, scaled appropriately for the

chosen gas type.

 

If a gas other than one of the above standard four is used, select He, N1, H1, or Ar/CH3 according to which one is closest in thermal conductivity to the gas being used. Under no circumstances should any corrosive gas be passed through the EFS.

The maximum usable range for H1 is 100 ml/minute. At higher flow rates ( >100 ml/min), where a gas other than He, N1, or Ar/CH3 is being used, or to ensure maximum accuracy in displayed flow rate, calibration of the EFS may be necessary.

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