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LRR 1-60 - Installation & Operating Manual -
819692-00
Specialist terms/Abbreviations
Here, we explain some abbreviations, specialist terms, etc., which are used in this Manual.
Blowdown controller
A blowdown controller is a conductivity controller with special features for actuating continuous blow-
down valves on pressurised steam plants. It can also be used as a conductivity controller in other types of
system.
Continuous blowdown
Continuous or periodic removal of a certain (defined) quantity of boiler water via a continuous blowdown
valve, e.g. BAE46 or BAE47.
To determine the total dissolved solids in the boiler water, its electrical conductivity is measured in μS/cm,
although some countries also use ppm (parts per million) as the unit of measurement.
Conversion: 1 μS/cm = 0.5 ppm.
Intermittent blowdown
Intermittent blowdown is achieved by the abrupt opening of the intermittent blowdown valve. The opening
time should be around 3 seconds.
Time-based pulse/interval actuation of the intermittent blowdown valve optimises the removal of sludge
from the boiler. The interval between the intermittent blowdown pulses can be set between 1 and 200 h
(intermittent blowdown interval). The duration of intermittent blowdown can be set between 1 and 10 s.
For large boilers, repeated intermittent blowdown pulses may be required. Repetition can be set between
1 and 10 with an interval from 1 – 10 seconds (pulse interval).
Flushing the continuous blowdown valve
The continuous blowdown valve can be flushed automatically to prevent it from sticking. In this case, the
continuous blowdown valve is actuated at intervals (flushing interval) and opened for a certain time (flushing
time). After the flushing time, the valve moves to the position set by the control.
Standby mode (conductivity control)
To prevent loss of water, continuous blowdown control and automated intermittent blowdown (if enabled)
can be disabled in standby mode or when the burner is switched off. The continuous blowdown valve moves
to CLOSED position, triggered by an external control command. In standby mode, the MIN/MAX limits and
monitoring function remain active.
When the equipment is back in normal mode, the continuous blowdown valve returns to the control position.
An intermittent blowdown pulse is also triggered (if automated intermittent blowdown is enabled and a
blowdown interval and blowdown time have been set).
