Chapter 4 – Functions of the instrument
UM-18400E-U ATEQ F580 User manual Page 97/168
At the end of test time 1, the ATEQ measures the pressure variation ∆P1, depending on
the transient and the leak if it is present.
∆P1 = Leak + Transient
Following the waiting time (equivalent to 5 times the test time), we consider that the
transient effects have disappeared. During the second test time, the ATEQ instrument
measures a second pressure variation ∆P2 corresponding to the leak.
∆P2 = Leak
By taking these two pressure variations, we can deduce the transient.
∆P1 - ∆P2 = (Leak + Transient) - Leak = Transient
This is the transient which will be taken away from the following leakage measurements.
Thanks to the ATR, the ATEQ instrument is capable of differentiating a good part from a
leaking part without being influenced by transient effects whilst maintaining a short
stabilisation time.
Associated parameters to be set: Initial (Initial value of the transient), Transit (actual and
non modifiable value of the transient), Tolerance (Drift tolerance on acquisition of the
transient, % of the reject level).
) Select the option and enter settings if necessary.
For ATR learning cycles, see paragraph 3.3.9. "ATR learning".
When a parameter is modified but no learning cycle has been carried out, an "ATR"
fault occurs. The "alarm" and "end of cycle" outputs are activated.
Learning may be carried out on a value greater than the reject level and the "Pass" and
"end of cycle" outputs are then activated. However, the "ATR" fault appears if the
difference between the transient and the initial value is greater than the reject level.
9 Transient drift
Due to the change over time of the test conditions (temperature variations,...), the value
of the transient can vary through time. It is therefore necessary to follow its evolution.
To avoid having to perform a learning cycle too often, the ATEQ instrument memorises
the last 10 values of parts considered as very good (result close to 0) and recalculates
the transient by working out the average.
The parts are considered as very good when their leakage rate is inferior to the
"tolerance" parameter of a % of the reject level. This value can be modified between 0
% and 100 %.
10
values parts good last 10 the of
Transient
∑
=
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