VEGA VEGATROL 10 Ex 1 - Manual (Page 16)

Technical data subject to alterations 2.16 207 / Sept. '94
VEGA Grieshaber KG
Postfach 11 42
D-77757 Schiltach
Phone 0 78 36 / 50 - 0
Fax 0 78 36 / 50 201
4 Supplement
4.3 General instructions for the use of overfill protections
Application of a liquid gas overfill protection (ÜFS) is to monitor the level of the liquid
gas stage and to interrupt the filling procedure when the permitted level in the vessel
is reached and to trigger an acoustic or optic alarm.
The configuration as well as the operation of such an overfill protection must always
meet with the requirements of an overfill protection as well as the special conditions
of the VdTÜV-regulation "overfill protection 100".
This furthermore requires that the filling of a pressuirzied vessel for liquid gas is only
possible if it is ensured that the overfilll protection works interferencefree and
correctly. At least before each filling procedure the whole measuring system of the
overfill protection must be checked. Normally this test of overfill protections is
triggered by a manually operated test key. In case of failure the filling must be
suppressed by a locking circuit.
Due to the self-monitoring, this test is not necessary with VEGATROL.
The overfill protection always operates discontinuously and can be planned and
operated independent from the function of the continuous level measurement. The
continuous level measurement is not subjected to the special requirements to the
functional reliability of the overfilll protection.
However both have to be included in an alarm system as follows:
-
the continuous measurement generates the pre-alarm signal and controls an
acoustic or optic warning system or interrupts the filling procedure
- the overfill protection triggers a main alarm signal and stops the system
Criteria for dimensioning:
-
triggering pre-alarm, e.g. at 83 % filling (dependent on the vessel geometry)
- triggering main alarm, generally at 85 % fllling
- tolerance of the switch point of the overfill protection:
±
1 %
The pre-alarm is adjusted such that there is sufficient time to avoid response of the
overfill protection.