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The default value for the low frequency cut-off is 0.1Hz, and the parameter is adjustable
from 0.1Hz up to 9.9Hz. It is not possible to enable a rate display for input frequencies below
0.1Hz.
5.9.3 Rate Calculation Pulses
The purpose of the ‘Rate Calculation Pulses’ parameter is to determine the number of input
pulses which are used in calculation of the flow rate; the more pulses which are used the more
accurately the Rate Display will represent the average flow rate of the system. The parameter
is adjustable from 1 to 99 pulses per calculation.
For systems using pumps with a non-uniform rate of delivery (piston pumps or similar) it is
important to have a high value for this parameter as it will produce a stable rate display which
is representative of the average flow through the pipe.
For systems with a steady and uniform flow through the pipe, lower values can be used for
this parameter in order to achieve a more responsive rate display. However, it should be kept
in mind that for any battery powered applications, using a value lower than the default will
decrease battery life.
5.9.4 Flow Rate Filter
The Flow Rate Filter is used to smooth out fluctuating flow input signals in order to provide a
stable flow rate display. Most input signals are reasonably stable and need only the default
setting, however for systems with large flow fluctuations the Filter setting may need to be
increased.
If the user requires quick visual indication of changes to a system’s flowrate, this can be
accomplished by entering a lower number. To remove all filtering from the flow rate
calculation this parameter can be set to zero.
5.9.5 Backlight Override
The backlight is automatically enabled whenever external DC power is connected to the
instrument; this feature may be overridden in this level of the program. The backlight override
may be set to ‘ON’ (normal function), ‘OFF’ (always off), ALARM (triggered with an alarm).
Note that the ALARM backlight mode still requires external DC power.
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