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VARIOMASS is a compressed air mass flow measurement and evaluation system which
consists of a thermal dispersion sensor (RTD) and a separate
digital transmitter electronics. Such systems allow highly
accurate compressed air mass measurements inside tubes with an
inside diameter of ½" to ND 500 (20"). The high
turndown ratio of 10: 1 to 800:1 provides both, accurate leakage
mass determination and quite common with big consumers, a
maximum value coverage. Example: the lowest measured value with
a ½" pipe is 3 liters per minute (0.1 SCFM) and the
maximum measured volume with a ND 500 (20") pipe is up to
50,000 cubic meters per hours (30,000 SCFM), related to nominal
conditions of 20°C and an absolute air pressure of 1 bar (68°F
@ 14.5 PSI).
A complete measurement system consists of a sensor
(single point insertion or In-Line), a connection cable, and a
sensor adjusted separate evaluation unit. There are two
different types of electronics available for the evaluation unit:
- the compact DIN panel mounting enclosure
- the robust in-field enclosure for wall mounting with
a protection class IP 65 (NEMA 4)
In addition to the total consumption of compressed air,
the operator can determine the consumption and exceeded limit
values over default periods which are pre-set by the operator.
The user can freely define and modify any system parameters
in-field. The user-friendly menu mode provides an uncomplicated
and safe programming and recall of the operational data. The
transmitter electronic in the field enclosure includes a newly
developed permanent self-monitoring system.
An addition to the total consumption of compressed air,
the operator can determine the consumption and exceeded limit
values over default periods which are pre-set by the operator.
The user can freely define and modify any system parameters
in-field. The user-friendly menu mode provides an uncomplicated
and safe programming and recall of the operational data. The
transmitter electronic in the field enclosure includes a newly
developed permanent self-monitoring system.
An additional relay output connection con be used for
remote monitoring of the system to indicate any break down or
failure of the measurement system to the external main station.
A description of the fault is given in the plain text by
pressing the blinking key FAULT' in the LCD Display of the
evaluation unit.
The sensors work in conformity with the
thermal dispersion measurement principle providing the following
advantages to the user:
·
fast and accurate
display of the mass flow
·
no moving parts,
i.e. maintenance-free
·
sensors insensitive
to pollution
·
pressure and
temperature compensated measurement
·
no pressure loss
caused by the sensor
·
high turndown-ratio
·
also suitable for
leakage measurement
·
quick and cost
effective assembly
·
ease of use,
flexibility
In addition to the gas and electricity metering is the
recording consumed compressed air mass an important factor when
manufacturing costs are calculated. The sharing and distribution
of the total costs to the separate production areas and cost
centers is very important for a precise analysis of the
operational efficiency and impending investments. Recording the
leakage mass and consumption peaks con help in optimizing pipe
and air pressure systems or to a demand oriented compressor
control thus leading to savings in energy consumption. There is
no special requirement to the quality of the compressed air with
view to cleanness. But the absolute humidity of the compressed
air shall not exceed 100%. A condensation of humidity in the
area of the measurement would result in a faulty measurement.
1) Central record of compressed air mass
The measuring system VARIOMASS provides a very accurate
determination of compressed air distribution within the factory
and to the different bleeding locations. This calculation is
done centrally with the bus interface (RS 485) and the soft-
ware WINVAR at the PC. Thus one can present a graphic display
and an evaluation of the consumption and the mass over several
periods of time. In addition to the display of the maxi- mum
mass flow values the current mass flow value of up to 31
measurement systems can be shown on-line and simultaneously in
the group window on the screen. Single units can be integrated
into a group, so one can calculate the total mass consumption
with a mouse click at the end of each month. Any graphic tables
and calculations con be exported to other programs or typed out
on a printer.
The single frame window displays all important basic
settings of the selected unit. These setting can be changed via
the respective menu item of the PC program and can be
transmitted to the measurement instrument.
The group frame window displays the current mass flow
values of any connected instruments. Several instruments con be
assigned with a color code to one of the 6 groups (cost centers).
Then the total consumption of the group con be calculated over a
specific period of time (e.g. one month). The graphs con display
the consumption or the mass flow value over several periods of
time (e.g. 9 hours, 24 hours, 1 month, or 1 year). The maximum
value of the selected period is given in connection with the
display of the numerical value, date and time.
2) Decentralized record of the compressed air mass flow
The compressed air evaluation system VARIOMASS can be
used as a mobile measuring system in a very flexible way. The
operator con program the measuring flow range and the inside
diameter of the pipe in the field via the keyboard. The
optionally available, retractable probe unit with a ball valve
permits an easy and safe drawing and mounting of the single
point insertion sensor under process conditions. To determine
the current gas mass flow and consumption values a memory chip
(4 MB data logger) is optionally available. This chip stores
over a period of up to one year the current mass flow values vs.
time and transmits them to a PC at the end of the period. Thus
in case of a temporary measurement with disconnected printer,
plotter, and data logger a precise record of the current
measurement values is possible. For such a mobile application we
can supply you a robust portable aluminum case with the
necessary tools for the measurement system.
3) Compressor control
The evaluation unit of the VARIOMASS measurement
systems can optionally be equipped with two relay switch
contacts, which can be programmed independently from each other.
These limit switches may be used as MIN and MAX alert during
mass flow monitoring and may switch on and off an additional
compressor. The operator via the keyboard sets the limit values.
Colored LED's (green/yellow) indicate the switch state of the
individual contacts. Alternatively these contacts can be used
for monitoring the meters totalizes reading: as soon as the
totalizes has reached a default value, the contacts (SPDT) will
close.
4) Determination of leakage mass flow
VARIOMASS measurement systems perform a precise
determination of leakage during production stand-still by means
of the programmable totalizes. Thus one of the totalizes can be
activated over the weekend by setting the start and stop time.
At the beginning of the new week the operator can read out the
leakage mass and the maximum mass flow by means of a keyboard
input. Due to the fact that all systems record mass flows of 0.1
SMPS (0.3 SFPS) or upwards, even the smallest leakage is
detected by the sensor probe. |