Fukuda FL-601 Series, Operational Manual

Page: 22 / 123

21
PRINCIPLE FITTING TESTER
CONVENTIONAL METHOD
FITTING TESTING
Detection Time
A conventional tester intentionally makes the pressurization time and the balancing time longer to
arrive in this stable zone and therefore it cannot take an accurate leak rate measurement in a
short amount of time.
An optional Master Tank (Stability Tank) has been provided for the FL-601.
By connecting this stability tank to the Master Port, the differential pressure generated in the
unstable zone on the master side is minimized. By doing this, only the actual properties of the
work side are sampled.
The FL-601 uses an approximation of these properties for operation.
The leak is calculated by using the actual data and the constant number generated when fitting
conditions (consistent characteristic property) are satisfied.
Y=aX + b(1 - e
cx
)------(formula 1
）
a; leak rate
b; differential pressure convergence without leak
c; work coefficient
X; detection time
Y; calculated differential pressure
Through fitting testing, one can determine the constants for (formula 1) a, b, and c.
By recording this constant as being a characteristic of the work, it is possible to conduct your
testing in a short amount of time. (The constants are determined by using the FittingSet option in
the leak tester settings).
While using this fitting testing method, since all the data collected during the detection process
(Setting item FDetect Time) is calculated using approximations, the more data that is available,
the more accurate the constants will become. With standard testing, the constants obtained during
this fitting testing are required, reducing the length of the detection test (Set Item Detect Time.)
SV3
SV2
SV1
MASTER
WORK
【
Conventional Circuit Diagram
】
The circuit diagram for conventional leak
testing, which uses a differential pressure
comparison, is similar to the diagram shown on
the right.
Testing is conducted by simultaneously
pressurizing both the master and work parts
then closing solenoid valves SV2 and SV3. After
that, the tester determines the leak rate by
observing the pressure alteration in both the
master and work chambers by using a
differential pressure sensor.
IR Regulator
With the pressure comparison leak
testing method, when the conditions of
the work and master parts (such as
volume and shape) are different, a large
amount of differential pressure tends to
be generated at the beginning of the
testing process.
（
unstable zone
）
After sufficient pressurization, it enters
a stable zone in which pressure only
varies when there is a leak present.
Master data
G
e
n
e
ra
te
d
d
iff
er
en
tia
l
pr
e
s
s
u
re
Unstable zone
Environmental
leak
Stable zone
Differential pressure
generated by leak
Masteri ng data
Actual leak rate
Estimated leak rate
Assuming the work and master conditions are the same, external environmental variation or
pressure variation caused by insufficient pressurization affect both equally, canceling any
adverse effects. Therefore, the differential pressure sensor does not react and testing time is
reduced.
(In reality, it is difficult to keep both the work and the master under the same conditions, due to equipment
restrictions or the requirements of various models, giving this differential pressure variation a certain
margin of error).
b Constant number