AMALGAMATED INSTRUMENT PM4-TR, Руководство по эксплуатации и инструкция

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7. Use the
^
or
v
push button to alter the previous scale value to the new scale value of 1.
8. Press
F
to accept the change then either press
P
to exit of continue pressing and releasing
F
until the
FUNC End
message is seen and the display returns to normal measurement
mode.
Example - Rotapulse flow sensor scaling
The “Rota pulse” paddle wheel flow meter (this sensor model is commonly used as an input
rate/total displays) outputs approx. 36.5 pulses per linear metre flow of liquid in a pipe. In this
example we will assume that the pipe internal diameter is 50mm (25mm or 0.025m radius).
The steps to calculate the scaling of the meter for this example are as follows:
1. Calculate the area of the pipe in square metres:
Area = π
×
r
2
= π
×
0.025
2
= 0.00196m
2
2. Calculate the volume of a 1m length of pipe:
Volume = Area
×
Length = 0.00196
×
1 = 0.00196m
3
3. For every 36.5 pulses we therefore have 0.00196 cubic metres of liquid or 1.96 litres of liquid
(there are 1000 litres in one cubic metre). For a litres/sec display we could therefore have
scaling factors of
RAtE INPt
=
3650
and
RAtE SCLE
=
196
.
The table below shows typical rate scaling factors for this flowmeter. Note that the examples in
the table can be reduced to smaller numbers as long as the ratio between the two numbers are
the same. The scaling factors above are approximate and will vary depending on pipe size and
installation conditions. A calibration should be carried out to determine the correct scaling for any
installation where accuracy is required
Rate table for Rota Pulse flow meter with 36.5 pulses per metre flow
Pipe dia. Litres/sec Litres/min Litres/hour m
3
/hr
25mm
RAtE INPt
=3650
RAtE INPt
=365
RAtE INPt
=365
RAtE INPt
=36500
RAtE SCLE
=49
RAtE SCLE
=295
RAtE SCLE
=17640
RAtE SCLE
=1764
40mm
RAtE INPt
=3650
RAtE INPt
=365
RAtE INPt
=365
RAtE INPt
=365
RAtE SCLE
=126
RAtE SCLE
=756
RAtE SCLE
=45360
RAtE SCLE
=45
50mm
RAtE INPt
=3650
RAtE INPt
=365
RAtE INPt
=365
RAtE INPt
=365
RAtE SCLE
=196
RAtE SCLE
=1176
RAtE SCLE
=70560
RAtE SCLE
=71
80mm
RAtE INPt
=3650
RAtE INPt
=365
RAtE INPt
=365
RAtE INPt
=365
RAtE SCLE
=503
RAtE SCLE
=3018
RAtE SCLE
=181080
RAtE SCLE
=181
100mm
RAtE INPt
=3650
RAtE INPt
=365
RAtE INPt
=365
RAtE INPt
=365
RAtE SCLE
=785
RAtE SCLE
=4710
RAtE SCLE
=282600
RAtE SCLE
=281
150mm
RAtE INPt
=365
RAtE INPt
=365
RAtE INPt
=365
RAtE INPt
=365
RAtE SCLE
=177
RAtE SCLE
=10620
RAtE SCLE
=637200
RAtE SCLE
=637
The table below shows typical total scaling factors for this flowmeter. Note that the examples in
the table can be reduced to smaller numbers as long as the ratio between the two numbers are
the same. The scaling factors above are approximate and will vary depending on pipe size and
installation conditions. A calibration should be carried out to determine the correct scaling for any
installation where accuracy is required
PM4TRMAN-2.7-0 55 of 58