Specifications

3. OPERATION

 OPERATION

To adjust the stability limit press [SETUP] and select <5stab>. The display is:

1. Entry field for setting the desired stability limit in the current

flow unit of measure. Recalls the default stability limit or the

last stability limit set.

Flow stability test:

0.5 sccm/s

Edit the stability limit setting as desired. Pressing [ENTER] activates the new stability limit

and returns to the current run screen.

The stability limit value is automatically converted when flow units of measure

are changed.

The [RES] setting affects the resolution of the stability limit value. If the stability limit

display does not have enough resolution to set the desired value, use [RES] to adjust the

resolution (see Section 3.4.9).

3.5.6 <6ADJ>

 PURPOSE

To apply adder (FA) and multiplier (FM) coefficients to the flow measured by molbox RFM.

PRINCIPLE

The ADJ function gives the user the capability to adjust mass flow readings made by molbox

RFM. This is accomplished by setting an adder and a multiplier.

The adder (FA) and multiplier (FM) adjust the displayed value of the flow through the molbloc

as calculated by the molbox RFM following:

corrected flow = (calculated flow * FM) + FA

If a K factor is active (see Section 3.4.1), the adder and multiplier are applied to the

calculated flow before the K factor is applied.

Using the Flow ADJ Function with molbloc-L to Handle a Gas Mixture

Use of ADJ to handle gas mixtures as described below is NOT valid with molbloc-S.

The flow ADJ function can be used to adjust flow readings to measure a gas mixture if the

molecular weight and relative content of each component gas is known. Note that this

method does not take into account the actual viscosity or compressibility factor of the gas

mixture. The thermodynamic properties of the highest concentration gas are used. Therefore,

the uncertainty in the measured flow is increased and the method is best when the highest

concentration gas is greater than 90% of the mixture.

To use this feature, set the molbox RFM [GAS] (see Section 3.4.2) to the highest

concentration gas, then adjust the flow multiplier by:

molecular weight of the mix

molecular weight of the gas selected on the molbox