Functional Testing
Senscient ELDS™
Rev 15
113
GB
In order to ensure that each SimuGas test is performed with the ELDS OPGD in the correct
state for such a test, following completion of each SimuGas test there is a 1 minute lock-
out period. During this lock-out period, SITE will not allow operators to command ELDS
Transmitters to perform SimuGas Auto or SimuGas Live tests. The operator is required to
wait until SITE indicates that it is possible to command SimuGas tests again.
5.3. SimuGas™ Live
A SimuGas Live test enables a SimuGas functionality test to be performed with the Receiver
signalling the quantities of gas calculated present in the monitored beam-path on its 4-20mA
output(s).
CAUTION
When a SimuGas Live test is performed, no warning flag is sent from the ELDS Transmitter to
the Receiver opposite to freeze the Receiver’s 4-20mA output(s). Unless the purpose of a
SimuGas Live test is to confirm correct initiation of executive actions by the connected Safety
Instrumented System (SIS), the user must take steps to ensure that live gas readings being
signalled on the 4-20mA output(s) of ELDS Receivers do not initiate un-wanted executive
actions. Where necessary, do this before performing SimuGas Live tests.
A SimuGas Live test can be commanded using SITE software running on an industrial computer
that is in communication with a Transmitter. Following receipt of a SimuGas Live command, the
Transmitter drives it laser diode(s) such that their outputs include Harmonic Fingerprints
corresponding to a pre-defined quantity of gas, and will hold this SimuGas level for 30 seconds
duration, subsequently returning to the ‘gas-free’ drive waveforms.
During the SimuGas Live test the Receiver will calculate the gas level(s) present in the monitored
beam-path as normal, and signal these readings over its 4-20mA output(s).
The results of a SimuGas Live test may be determined by comparison of the gas reading(s)
signalled by the Receiver during the test with the gas level(s) that the Transmitter was simulating.
1) See section 5.4 “SimuGas Levels” for details of the levels of SimuGas synthesised
during SimuGas Live tests.
2) In the event that a SimuGas Live test is performed when there is real target gas in the
beam-path, the amount of gas seen and signalled by the Receiver will be the sum of
the SimuGas level and the real gas level. Since any real target gas levels present in an
open beam-path will tend to fluctuate, the summed reading signalled during a SimuGas
Live test performed under such conditions will also fluctuate. This fluctuation should not
be interpreted as a problem with the ELDS system or the SimuGas Live test, it is a
complication arising from the conditions in the beam-path when the SimuGas test was
performed.
3) Due to the potential complication noted at 2) it is preferable to perform SimuGas Live
tests when there is no real gas in the monitored beam-path. This can most easily be
established by checking the gas readings from the Receiver before performing a
SimuGas test. If the gas readings are stable at zero, SimuGas Live testing results will
be simpler to interpret.
4) In order to ensure that each SimuGas test is performed with the ELDS OPGD in the
correct state for such a test, following completion of each SimuGas test there is a
1 minute lock-out period. During this lock-out period, SITE will not allow operators to
command ELDS Transmitters to perform SimuGas Auto or SimuGas Live tests. The
operator is required to wait until SITE indicates that it is possible to command SimuGas
tests again.
Summary of Contents for Senscient ELDS 1000 series
Page 58: ...Installation Commissioning 58 Senscient ELDS Rev 15 GB 2 x Mounting Brackets ...
Page 140: ...Certification 140 Senscient ELDS Rev 15 GB 9 1 2 Control Drawing CENELEC ATEX ...
Page 142: ...Certification 142 Senscient ELDS Rev 15 GB 9 1 4 Control Drawing CSA US Canada ...
Page 159: ...Appendix D Manufacturer s EC Declarations Senscient ELDS Rev 15 159 GB ...
Page 160: ...Appendix D Manufacturer s EC Declarations 160 Senscient ELDS Rev 15 GB ...
Page 184: ...For local MSA contacts please visit us at MSAsafety com Because every life has a purpose ...