| The
problem with gas interlocks in catering
kitchens:
Monitoring Pressure Differential is not proving airflow
Current, pressure switch-based gas proving systems monitor air pressure
differential between the inside of the extractor duct and the kitchen
in order to decide the canopy fan is running safely. When the pressure
differential drops below a fixed threshold, the gas proving system assumes
that fan speed is too low for safety and cuts off the gas.
Even if the user is doing no more than boiling an egg using a single,
small burner, the extractor fan must be run at same high speed needed
to provide safe operation with all gas appliances going full blast.
Even more problematic, relying solely on the presence -- or absence --
of pressure differential at a particular point inside the cooker canopy
cannot provide a reliable indication of extractor fan performance. Turbulence,
blocked grease filters, wind gusts or vibration might affect the canopy
airflow, for example. Or there might be a simple fault, such as a blocked
pipe, leading to a false reading and cutting the gas off instantly and
without warning.
This is why traditional gas proving systems can cause spurious automatic
cut-off, needless call-outs, and kitchen staff who don't trust the gas
safety system. Ultimately, it can also lead to unauthorised, unsafe workarounds
such as bypass switches.
The Fan Proving Safety Solution:
indigoswitch uses a venturi inside the extract duct to prove airflow as
well as a a current monitor on the extract fan and a thermostat next to
the canopy edge to switch the solenoid off when it is not safe to use
gas as well as ensuring that the gas stays on when the extraction is ok.
Conceived and designed by a CORGI-registered gas engineer with many years
of experience with commercial catering installations, indigoswitch
solves these problems by doing more than simply measuring the pressure
differential: it also monitors canopy spillage and the electrical current
drawn by the fan. A venturi mounted, adjustable pressure switch reads
the airflow inside the canopy, while one or more thermostats detect combustion
products spilling from the canopy.
This
flexible approach means that indigoswitch
can continue supplying gas safely in circumstances where other systems
would trip off.
indigoswitch
has front-panel indicators to provide feedback and user-confidence in
operation, and to assist with faultfinding in the event of any problems.
indigoswitch
comes with full installation and operating instructions, and a one-year
back-to-base warranty.
New: deluxe version with doubled
up timer relay and changeover switch. Together with dual parrallel gas
solenoids this will eliminate downtime of the kitchen due to interlock
system component failure.
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