Liquid Controls HML4-F1 - LCMag - Manual (Page 27)

HML4-F1
27
MENU 3 – MEASURE
(POS. 3.2) Measure filter [M. filter=s XXX.X]
This section of the manual is extremely important because the right settings of filters allow to get a
proper meter reaction according to the flow rate behaviour.
WORKING PRINCIPLE
There are two filters:
MFSLN (Measure Filter Slow LeNght): available via ETP and through the display, in menu
3. Measure, function “M. filter”
The M. filter function effects the converter response time while measuring (it is like LOW PASS
filter); the value needs to be chosen carefully as it effects the meter behaviours. A smaller value
with a fluctuating flow will lead to unstable flow readings as the integration filter will be measuring
over very short periods. A higher value corresponds to a more stable but slower measure, a smaller
value gives a faster measure but is more unstable.
MFFLN (Measure Filter Fast LeNght): is available ONLY via ETP
The MFFLN must be set by the user in accordance with the MFSLN (M. filter) to meet the required
meter behaviour.
How the system functions: If the period of flow rate variation is over the MFFLN time (i.e. a slow
flow variation), the outputs (display/4-20mA/Alarms) are refreshed according to MFSLN (M. filter);
as soon as the flow rate variation is within MFFLN time, the output will be set immediately at the
new value.
The combination of MFSLN & MFFLN is useful as it allows the converter to react quickly to large
flow rate variations, regardless of the MFSLN (M. filter) set, therefore delaying (dampening) smaller
fluctuations in flow, resulting in very stable measures.
The value of those parameters has to be within the range from 0 (filter disabled) to the maximum
value defined on below table:
Sampling rate M Filter (MFSLN) F Filter (MFFLN)
20 50.0 7.50
50 20.0 3.00
60 16.7 2.50
80 12.5 1.88
150 6.7 1