VEGA FLEX60 User Manual
Supple
mentary information
Recurring function
for VEGAFLEX series 60
test
Document ID:
36552
1 Conte
nts
Conten
1 About this document
2 Prerequisites
3 Sequence of the recurring function test
4 Result of the recurring function test
5 Test protocol - Recurring function test
ts
2.1 Authorised personnel . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Required tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Required comparative data . . . . . . . . . . . . . . . . . . . .
2.4 Required plant situation . . . . . . . . . . . . . . . . . . . . . .
3.1 Restart of the sensor . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Verification of the current output . . . . . . . . . . . . . . . .
3.3 Verification of the instrument parameters . . . . . . . . . .
3.4 Verification of echo data . . . . . . . . . . . . . . . . . . . . . .
3.5 Sensor reaction to a level change . . . . . . . . . . . . . . .
5
5
5
5
7
9
10
11
12
2 Recurring
36552-EN-100225
function test • for VEGAFLEX series 60
out this document
1 Ab
Why a function test?
Fault detection rate λ
92 %
1 Abou
t this document
The recurring function test serves to check the safety function and
reveal possible undetected, dangerous failures (λ
). The functional
du
capability of the measuring system has to be tested in adequate time
intervals. It is the user's responsibility to select an appropriate type of
testing. The time intervals are subject to the PFD
-value according to
avg
the specifications in the Safety Manual (SIL).
With high demand rate, a recurring function test is not requested in
IEC 61508. The functional efficiency of the measuring system is
demonstrated by the frequent use of the system. In double channel
architectures it is a good idea to verify the effect of the redundancy
through recurring function tests at appropriate intervals.
With this supplementary information you can carry out a recurring
function test of level sensors VEGAFLEX 61, 62, 63, 65 and 66 without
dismounting the instrument or moving the level of the medium to the
switching point.
With this procedure, 88 % or 92 % of all dangerous undetected
instrument failures (λ
) are detected (DC
du
Proof
).
The described function test fulfils the requirements according to SIL.
If you have already created a sensor documentation during setup, you
du
can check the sensor at a detection rate of 92 % of all dangerous
undetected failures.
The remaining dangerous undetected failures are 11 FIT.
FIT = Failure In Time (1 FIT = 1 failure/10
9
h)
Fault detection rate λ
88 %
36552-EN-100225
Recurring
function test • for VEGAFLEX series 60 3
e sure that also a later sensor documentation is possible. This
Mak
sensor documentation of a recurring function test must be at least 6
months old.
If you created no sensor documentation during setup, you can check
du
the sensor only at a detection rate of 88 % of all dangerous undetected
failures.
The remaining dangerous undetected failures are in this case 16 FIT.
9
FIT = Failure In Time (1 FIT = 1 failure/10
h)
1 A bou
t this document
ase note the Ex-specific safety information for installation and
Ple
operation in Ex areas. These safety instructions are part of the scope
of delivery and come with the Ex-approved instruments.
Warning:
The recurring function test influences connected devices. Take note
that downstream devices may be activated during the test.
Informa
tion:
Proceed according to the specified, recommended sequence of these
instructions to isolate possible device failures systematically.
Informa
tion:
Document the recurring function test, for example, in the test protocol
in the supplement. To facilitate the recording and for further function
tests, we recommend to copy the empty test protocol before
completing it.
This supplementary information manual can be downloaded from our
download section.
Th
e recurring function test cannot replace the prescribed test
according to WHG (Water Resources Act).
4 Recurring
36552-EN-100225
function test • for VEGAFLEX series 60
2 Prer
equisites
2 Prere
quisites
2.1 Authorised personnel
All operations described in this operating instructions manual must be
carried out only by trained specialist personnel authorised by the plant
operator.
During work on and with the device the required personal protective
equipment must always be worn.
2.2 Required tools
l This test instruction
l PACTware
l Actual VEGA DTM Collection
l Device-DTM of the corresponding sensor (part of the VEGA DTM
Collection)
l Communication-DTM (part of the VEGA DTM Collection)
l Interface adapter VEGACONNECT
l mA-meter or PLC resp. DCS (accuracy ≤±0.2 %)
l Operating instructions manual of the sensor
l Safety Manual
2.3 Required comparative data
The setup data should be used for verification of the settings.
The following setup data are required:
l Sensor documentation of the setup with all parameters or a sensor
documentation created at least 6 months ago
l Documentation of all parameter changes since the setup
36552-EN-100225
Recurring
the sensor documentation of the setup or a sensor documentation
If
created at least 6 months ago is not available, then the described
recurring function test (λ
92 %) cannot be carried out completely. In
du
this case, only the test at a detection rate of 88 % of all dangerous,
undetected failures is possible.
2.4 Required plant situation
Caution:
e sure that there are no considerable process-relating changes in
Mak
your plant during the recurring function test. This means also that the
level in the vessel should not change significantly by filling or emptying
during the test. Make sure that also temperature changes, stirrers,
current reactions in the vessel, etc. can cause level changes.
function test • for VEGAFLEX series 60 5
0
0
V
dB
3
1
2
2 P rereq
uisites
tion:
Informa
Document the recurring function test, for example, in the test protocol
in the supplement.
The following conditions must be fulfilled when performing the
recurring function test:
Fig. 1: Level
1 Echo curve
2 Logarithmic echo curve
3 Amplitude of the useful echo (logarithmic echo curve)
echo - VEGAFLEX
l The process conditions must be nearly constant (level, process
pressure, process temperature)
l The medium must be the same as during setup or the medium
must at least belong to the same product group.
- Solvents/Liquid gases/Hydrocarbons/Oils (DK value < 3)
- Chemical mixtures (DK value 3 … 10)
- Water/Acids/Bases (DK value > 10 or conductive)
l The level must be either in the following areas:
- Distance to the process fitting ≥ 200 mm.
- Min. covering of the rod electrode ≥ 100 mm/cable electrode
≥ 250 mm.
-
- or the following requirement must be fulfilled:
-
- Reliability at least 20 dB (amplitude of the useful logarithmic
echo above the noise level). The reliability can be verified
during the test.
36552-EN-100225
6 Recurring
function test • for VEGAFLEX series 60
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