DH Instruments COMPASS FOR MOLBOX User Manual Download Page 72

Page: 72 / 226

COMPASS



for molbox™ User’s Manual

DH Instruments, Inc

Page 58

Set

flow

point:

The flow test point is set. The method used to set the flow is determined

by the

<Flow Control>

selection in the Test Definition (see Section 9.5.6). If flow setting

is manual, the user is prompted to set the flow to the flow point value. If flow setting is
automated, flow is set automatically using either the DUT or the selected flow controller.
In manual flow control, once

<OK>

has been pressed to confirm the flow is set,

test execution continues. If a 0 flow set point is specified and the prompt for manual
valve shut-off option is selected in

[Tools]

[Options]

[Run Test]

(see Section 11.6),

a message displays requesting that the user operate the necessary valves to achieve 0 flow.
In this case, no automatic flow control is used. When the flow is set, testing for stability
begins (see Section 7.1). In automated control, if the stability test times out, the

<Status>

column of the Data Grid and Data File displays

<s>

(see Section 18.4). After completing

the flow stability test, test execution continues.

Tare molbox:

If the current test point requires a tare (see Section 9.5.2) and the

reference is a molbox, the molbox internal valves are adjusted for taring and the

<Tare>

window displays. If

<Wait for Enter to tare>

is checked in the Test Definition, the user

must click the

<Tare>

button to set the current tare. The

<Tare Window>

does not

automatically close after the tare is complete. The user must press

<Continue>

or close

the window to continue test execution. Pressing

<Continue>

without taring does not

cause an error. If

<Wait for Enter to tare>

is not checked in the Test Definition,

COMPASS

waits for pressure stability then automatically executes the tare function.

COMPASS

will repeat the automated tare procedure up to three times if errors are

encountered during taring. If a tare value is set, the new tare information is stored in the

<Tare DP>

and

<Tare MDP>

Grid and Data File columns (see Section 18.4). The

<Status>

field also includes a

<t>

to flag that a tare occurred.

Jog before dwell:

If jog mode is selected in the Test Definition (see Section 9.5.6),

the

<Flow Control>

window displays with only the

<Target Flow>

and

<Jog>

buttons

active (see Section 6.6.8). Use these control functions in the necessary combination to
set the desired flow. Typically,

<Jog>

is used to adjust the flow to put the indication of a

flow meter on its cardinal point if desired. This feature is often used when testing a
rotameter or other visual flow indicator with a graduated scale.

Dwell:

If timed dwell is specified in the Test Definition (see Section 9.5.4), the dwell time

counts down and execution continues. If the Test Definition specifies manual dwell,

COMPASS

waits for the operator to press

<OK>

on the

<Dwell Complete>

dialog box

before test execution continues.

Take

data:

Following the settings in the Test Definition

[Data]

tab, the reference, DUT and

measured DUT set point are read as many times as possible for the averaging period
(see Section 9.5.9). If timed averaging is specified in the Test Definition (see Section 9.5.4),
the averaging time counts down as the flow data is averaged. If manual averaging is selected,
a message displays awaiting confirmation of when to start averaging. A fixed averaging
time can be entered in this window if desired. If the fixed time is entered and the

<Fixed Average>

button is pressed, the averaging process continues just as though a fixed time were
specified in the Test Definition. If the manual average is used, a new message displays
awaiting confirmation of when to end averaging. The elapsed time displays on the window
until the average is ended. Averaging occurs only for references and DUTs that can be
read automatically. In the event that the current test point is 0 flow and the

<Force zero flow>

option is selected in the

[Tools]

[Options]

[Run Test]

tab (see Section 11.6), the reference

flow value logged is 0 regardless of its actual value. Step

is repeated for each

reading/point specified in the test.

If this is not the last point in a test cycle, the sequence repeats starting with the Step

Change molbloc

. If this is the last point in a test cycle, the

[Tools]

[Options]

[End Test]

tab (see Section 11.7) last point selection is used to determine what to do

after the last point. During all other test points, pressing the

<Step Back>

run toolbar

option (see Section 6.5.1) allows points to be repeated by stepping back through the
point sequence. Since a new cycle begins or the test ends immediately following the last
point, this special option is used to allow the user to repeat a point.

When run test is complete, test conclusion begins (see Section 7.2.3).