mru VARIOluxx User manual

9452EN-OPT
USER MANUAL
OPTION
Gas ow
measurement
VARIOluxx
MGAluxx
MGAprime

MRU
2 / 8 Version 01 OPTION Gas ow measurement
Content
1 Gas ow measurement............................................................................................................... 3
1.1 Setting the parameter.....................................................................................................................3
1.1.1 Assign a measured value ......................................................................................................3
1.1.2 Set parameters ........................................................................................................................4
1.1.3 Store the measurement results ..........................................................................................5
1.1.4 Continuous data logging......................................................................................................5
1.1.5 Export der Messung auf SD-Karte .....................................................................................5
2 Appendix....................................................................................................................................... 6
2.1 Calculating the molar mass...........................................................................................................6
2.2 Calculating the gas density ..........................................................................................................6
2.3 Calculating the current Flow velocity........................................................................................6
2.4 Calculating the current volume ow.........................................................................................7
Legal notices / Intellectual property rights comments
Original user manual
© 2018 by MRU
No part of this manual my be published in any form (print, photocopy, electronic media or
any other publication form) without a written approval by the publisher.
All user trade marks and name mark descriptions, even those which are not marked as such,
are properties of the respective owners.
Edition: 2018-08-14, V01

MRU
3 / 8Version 01
Gas ow measurement
OPTION Gas ow measurement
1 Gas ow measurement
This option allows the user to determine the gas velocity at a single poin
by means of a pitot tube (order separately). Based on the dierential
pressure between the ports of the pitot tube and the absolute pressure,
the gas velocity is calculated. The gas density as measured by the instru-
ment is taken into account.
Assuming the measured gas velocity is represenative for the gas ow in a
duct, the ow rate is calculated as the product of the measured velocity
and the duct's cross section area which can be inserted accordingly.
1.1 Setting the parameter
Before measuring you must enter all parameters for the gas ow mea-
surement in the menu Measure.
1.1.1 Assign a measured value
fDouble touch the value eld.
ÖA list with of all available measured values is displayed.
fChoose the wanted value and“replace”or "insert".

MRU
4 / 8 Version 01
Gas ow measurement
OPTION Gas ow measurement
1.1.2 Set parameters
fSelect in the context menu Gas ow measurement.
fEnter the value„Pitot factor“. Please take the value from the documen-
tation of the used pitot tube.
fSelect CHOOSE UNTIS
fSelect the wanted units fpr the measurements

MRU
5 / 8Version 01
Gas ow measurement
OPTION Gas ow measurement
Cross-section area
For measuring the gas ow must be known the cross-section area.
fSelect the geometry of the cross-section area,
circle, square or rectangle.
fEnter the required value.
ÖThe cross-section area will be calculated.
After returning to the measuring menu, the measurement starts auto-
matically.
If necessary, you can zeroing via the context menu.
1.1.3 Store the measurement results
The measured values can be stored in a site via the context menu / Store
menu entry.
The measurement itself continues until switch o of the analyzer
1.1.4 Continuous data logging
A continuous measurement logging is possible via the context menu /
“Start logging”.
With“Start Logging”, the currently measured values are stored in a site
every 10 seconds.
End the data logging with“Stop logging”.
1.1.5 Export der Messung auf SD-Karte
In the menu Contacts you can export the measurements by the ex-
change format CSV on a SD-card.

MRU
6 / 8 Version 01
Appendix
OPTION Gas ow measurement
2 Appendix
2.1 Calculating the molar mass
The molar mass of a gas depends on the gas proportions. This will be
calculated on the equation 1
Equation 1: molar mass
M = 0.00001* (32*[O2] + 44*[CO2] + 18*[H2O] + 16*[CH4] + 28*[N2])
[O2]: oxygen in [%]
[CO2]: carbon dioxide in [%]
[CH4]: methane in [%]
[H2O]: water in [%]
[N2]: nitrogen in [%]
Unit of molar mass
2.2 Calculating the gas density
The gas density is calculated on the equation 2:
Equation 2: gas density
p: gas density in
Pabs: indicated the absolute pressure in [Pa]
M: molar mass in
R: gas constant, amounts 8.134
]
*
[Kmol
J
Tgaz: gas temperature in Kelvin
2.3 Calculating the current Flow velocity
The ow velocity by pitot tube will be determined by means of the mea-
sured pressure and density (see equation 3).
Equation 3: ow velocity
: ow velocity in [m/s]
: pressure dierence in [Pa]
ρ
P
v∆ =*2
~
P∆

MRU
7 / 8Version 01
Appendix
OPTION Gas ow measurement
: mean value of pressure dierence in [Pa]
p: density of gas in
The geometry of the used pitot tube will be considered by the pitot fac-
tor.
Equation 4: ow velocity with pitot factor
pitot
K
: pitot factor
2.4 Calculating the current volume ow
The current volume ow is, the current Flow velocity multiplied by the
cross-section area.
Equation 5: volume ow
qv,mom = vmom * A
qv,mom: current volume ow in [m³/s]
vmom: current Flow velocity in [m/s]
A: cross-section area in [m²]