BRONKHORST IN-FLOW User manual

Instruction manual
General instructions digital
Mass Flow / Pressure instruments
laboratory style / IN-FLOW
Doc. no.: 9.17.022V Date: 12-01-2016
ATTENTION
Please read this instruction manual carefully before installing and operating the instrument.
Not following the guidelines could result in personal injury and/or damage to the equipment.

BRONKHORST®
SCOPE OF THIS MANUAL
This manual covers the general part of digital massflow / pressure instruments for gases
or liquids. It handles the general instructions needed for the instruments.
More information can be found in other documents.
Multibus instruments have modular instruction manuals consisting of:
-General instructions digital Mass Flow / Pressure instruments
laboratory style / IN-FLOW (document nr. 9.17.022)
-Operation instructions digital instruments (document nr. 9.17.023)
-Fieldbus/interface description:
-FLOW-BUS interface (document nr. 9.17.024)
-PROFIBUS–DP interface (document nr. 9.17.025)
-DeviceNet interface (document nr. 9.17.026)
-RS232 interface with FLOW-BUS protocol (document nr. 9.17.027)
-Modbus interface (document nr. 9.17.035)
-EtherCAT interface (document nr. 9.17.063)
-PROFINET interface (document nr. 9.17.095)

BRONKHORST®
Even though care has been taken in the preparation
and publication of the contents of this manual, we do
not assume legal or other liability for any inaccuracy,
mistake, mis-statement or any other error of
whatsoever nature contained herein. The material in
this manual is for information purposes only, and is
subject to change without notice.
Warranty
The products of Bronkhorst®are warranted against
defects in material and workmanship for a period of
three years from the date of shipment, provided they
are used in accordance with the ordering specifications
and the instructions in this manual and that they are
not subjected to abuse, physical damage or
contamination. Products that do not operate properly
during this period may be repaired or replaced at no
charge. Repairs are normally warranteed for one year
or the balance of the original warranty, whichever is the
longer.
See also paragraph 9 of the Conditions of sales.
The warranty includes all initial and latent defects,
random failures, and undeterminable internal causes.
It excludes failures and damage caused by the
customer, such as contamination, improper electrical
hook-up, physical shock etc.
Re-conditioning of products primarily returned for
warranty service that is partly or wholly judged non-
warranty may be charged for.
Bronkhorst High-Tech B.V. prepays outgoing freight
charges when any party of the service is performed
under warranty, unless otherwise agreed upon
beforehand. However, if the product has been returned
collect to Bronkhorst High-Tech B.V., these costs are
added to the repair invoice. Import and/or export
charges, foreign shipping methods/carriers are paid for
by the customer.

BRONKHORST®
Short-Form Operation Instruction
Before installing your Mass Flow or Pressure
Meter/Controller it is important to read the attached
label and check:
- flow/pressure rate
- fluid to be metered
- up- and downstream pressures
- input/output signal
Check the red-coloured sticker and make sure the
testpressure is in agreement with normal safety factors
for your application.
Check if the piping system is clean. For absolute
cleanliness always install filters to assure a clean,
moisture- and oil-free gas stream.
Install the Meter/Controller in the line and tighten the
fittings according to the instructions of the supplier of
the fittings. Choose the mounting position according to
the directions given in this manual.
Check the system for leaks before applying fluid
pressure
In systems with corrosive or reactive fluids, purging
with an inert gas is absolute necessary before use.
Complete purging after use with corrosive or reactive
fluids is also required before exposing the system to
air.
Electrical connections must be made with a standard
cable or according to the hook-up diagram in the back
of this manual.
Short form start-up
Install instrument in your process.
Provide instrument with correct pressure(s)
Analog operation
Connect the instrument to the power supply/readout
unit with the 9-pin cable at the DB-9 connector /
8 DIN connector

BRONKHORST®
BUS/digital operation
For this procedure: See description for specific fieldbus
Send a setpoint to the instrument and check the
measured value
Let the instrument warm-up for 30 minutes for best
accuracy
Your Mass Flow/Pressure Meter/Controller is now
ready for operation.
! Caution
Operation via fieldbus is done by means of a flatconductor
cable connected with the main PC board.
Although all functionality is possible by means of RS232
and the switch on top of the instrument, it is important
that care should be taken when removing the upper part
of the housing.

BRONKHORST®

BRONKHORST®
TABLE OF CONTENTS
1Introduction ................................................................................................................................................... 9
1.1General description................................................................................................................................ 9
1.1.1Gas flow.......................................................................................................................................... 9
1.1.2Liquid flow....................................................................................................................................... 9
1.1.3Pressure ......................................................................................................................................... 9
1.1.4Housings......................................................................................................................................... 9
1.1.5Valves........................................................................................................................................... 11
1.2Sensor principles ................................................................................................................................. 12
1.2.1Gas flow sensors (by-pass measurement)................................................................................... 12
1.2.2Gas flow sensors (direct mass flow measurement, CTA based) ................................................. 12
1.2.3Liquid flow sensors ....................................................................................................................... 12
1)The  -FLOW model for flowrates up to 2 g/h.......................................................................................... 12
2)The CTA based LIQUI-FLOW model for flow rates up to approximately 1000 g/h................................. 13
1.2.4Pressure sensor ........................................................................................................................... 13
1.3Valve principles.................................................................................................................................... 13
1.3.1Solenoid valve .............................................................................................................................. 13
1.3.2Vary-P valve ................................................................................................................................. 13
1.3.3Pilot operated valve ...................................................................................................................... 14
1.3.4Bellows valve................................................................................................................................ 14
1.4Kv-value calculation ............................................................................................................................. 14
1.4.1For gases...................................................................................................................................... 14
1.4.2For liquids ..................................................................................................................................... 15
1.4.3Maximum pressure drop............................................................................................................... 16
1.5Sensors and laminar flow devices....................................................................................................... 16
1.6Conversion factors............................................................................................................................... 17
1.6.1Gas conversion factors (by-pass measurement) ......................................................................... 17
1.6.2Gas Conversion Factors (direct mass flow measurement, CTA-based)...................................... 18
1.6.3Liquid Conversion Factors............................................................................................................ 19
1.6.4Software for conversion factor calculation ................................................................................... 19
2Installation ................................................................................................................................................... 20
2.1Receipt of equipment........................................................................................................................... 20
2.2Return shipment .................................................................................................................................. 20
2.3Service ................................................................................................................................................. 20
2.4Mounting .............................................................................................................................................. 21
2.5In-line filter ........................................................................................................................................... 21
2.6Fluid connections................................................................................................................................. 21
2.7Piping ................................................................................................................................................... 22
2.8Electrical connections.......................................................................................................................... 22
2.9Caution................................................................................................................................................. 22
2.10Supply pressure ............................................................................................................................... 23
2.11System purging ................................................................................................................................ 23
2.12Seals ................................................................................................................................................ 23
2.13Equipment storage ........................................................................................................................... 23
2.14Electromagnetic compatibility .......................................................................................................... 23
2.14.1Conditions for compliance with EMC requirements ..................................................................... 23
3OPERATION............................................................................................................................................... 25
3.1General ................................................................................................................................................ 25
3.2Power and warm-up............................................................................................................................. 25
3.3Zeroing................................................................................................................................................. 25
3.4Start-up ................................................................................................................................................ 26
3.5Operating conditions............................................................................................................................ 26
3.6Instrument performance ...................................................................................................................... 26
3.6.1Sensors ........................................................................................................................................ 26
3.6.2Controllers .................................................................................................................................... 26
3.7Manual operation ................................................................................................................................. 26
3.8Analog operation.................................................................................................................................. 27
3.9BUS / digital operation ......................................................................................................................... 27
4Maintenance ............................................................................................................................................... 28
4.1General ................................................................................................................................................ 28
4.2Gas flow sensor ................................................................................................................................... 28

BRONKHORST®
4.3Liquid flow sensor ................................................................................................................................ 28
4.4Pressure sensor................................................................................................................................... 28
4.5Controllers ........................................................................................................................................... 28
4.6Control valves ...................................................................................................................................... 28
4.6.1Solenoid valves ............................................................................................................................ 29
4.6.2Vary-P valve ................................................................................................................................. 29
4.6.3Pilot operated valve ...................................................................................................................... 29
4.6.4Bellows valve................................................................................................................................ 29
4.7Calibration procedure .......................................................................................................................... 29
5Digital instrument ........................................................................................................................................ 30
6Interface description.................................................................................................................................... 30
7TROUBLESHOOTING................................................................................................................................ 30
7.1General ................................................................................................................................................ 30
7.2Troubleshooting summary general...................................................................................................... 31
Appendices
1 Gasconversion table
2 Dimensions digital cases
3 Enclosures (if applicable)

BRONKHORST®
9.17.022 page 9
1 Introduction
1.1 General description
1.1.1 Gas flow
The Bronkhorst®series mass flow meter for gases is an accurate device for measuring gas flows up to 700
bar depending on body rating, virtually independent of pressure and temperature changes.
The system can be completed with a control valve and flexible readout to measure and control gas flows
from 1 mln/min up to several thousand m3
n/h, depending on the specific type of instrument.
For limited flow ranges a metal sealed model is available.
1.1.2 Liquid flow
The Bronkhorst®mass flow meter for liquids is an accurate device for measuring liquid flows up to 400 bar
depending on body rating, virtually independent of pressure and temperature changes. The system can be
completed with a control valve to measure and control liquid flows from 2g/h up to 1000g/h.
1.1.3 Pressure
The Bronkhorst®pressure meter measures pressures from 100 mbar up to 400 bar depending on body
rating, either absolute pressure or gauge pressure and in the range 0 to 15 bar differential pressure too. The
pressure controller controls pressure with a very high accuracy and repeatability. The controller is available
in forward control (P-600 series) and backward control (P-700 series).
The flow going through the pressure controller depends on up and downstream pressures, the orifice
diameter of the valve and kind of fluid.
1.1.4 Housings
Each instrument housing style incorporates several provisions to comply with EMC requirements.
EL-FLOW®, EL-PRESS
The p.c.board is placed in a metalized plastic cover. For electrical connection the
instrument has a male 9-pin miniature sub-D connector for analog/RS232
operation. For digital operation the instrument has various connectors on top. These
instruments are suited for dry (indoor) applications, like laboratories and in well
protected (OEM) housings.
EL-FLOW® , EL-PRESS metal seal
This series has the same housing as the standard EL-FLOW®, EL-PRESS series,
but this series distinguish itself by metal-to-metal seals.

BRONKHORST®
page 10 9.17.022
IN-FLOW , IN-PRESS
To comply with the IP65 ingress protection standard, the p.c. board is housed in a
sealed casted metal housing. For electrical connections the instrument has a 8DIN
male connector for analog/RS232 operation and for digital operation various
connectors on top. These instruments are suited for light industrial (outdoor) use to
IP65.
LIQUI-FLOW®
Two different digital-liquid flow meters can be distinguished:
-FLOW model
The -FLOW model for up to 2 g/h, basically a straight capillary tube with a sensor.
For electrical connection the instrument is equipped with a male 9-pin sub D-
connector. The instrument is suited for dry (indoor) applications like laboratories.
CTA based LIQUI-FLOW
The CTA based LIQUI-FLOWmodel for flow rates up to approximately 1000 g/h.
For electrical connection the instrument is equipped with a male 9-pin sub D-
connector. The instrument is suited for dry (indoor) applications like laboratories.
To comply with the IP65 ingress protection standard, the p.c. board is housed in a
sealed casted metal housing. For electrical connections the instrument has a 8DIN
male connector for analog/RS232 operation and for digital operation various
connectors on top. These instruments are suited for light industrial (outdoor) use to
IP65.

BRONKHORST®
9.17.022 page 11
1.1.5 Valves
Laboratory style
For gases:
The solenoids of these valves have an IP50 ingress protection class.
This means that the valves are suited for dry (indoor) use.
For liquids:
The solenoids of these valves have an IP50 ingress protection class.
This means that the valves are suited for dry (indoor) use.
This valve is equipped with a purge connector.
Industrial style
For gases:
The solenoids of these valves have an IP65 ingress protection class. This means
that they are suited for light industrial (outdoor) use.
For liquids:
The solenoids of these valves have an IP65 ingress protection class. This means
that they are suited for light industrial (outdoor) use.
This valve is equipped with a purge connector.

BRONKHORST®
page 12 9.17.022
1.2 Sensor principles
1.2.1 Gas flow sensors (by-pass measurement)
The majority of gas flow sensors operate according to the by-pass measurement principle. These types of
instruments operate on a principle of heat transfer by sensing the delta-T along a heated section of a
capillary tube. Part of the total flow is forced through the capillary by means of a laminar flow device in the
main stream generating a delta-p.
The design of the laminar flow device is such that flow conditions in both the capillary and laminar flow
device are comparable, thereby resulting in proportional flow rates through the meter. The delta-T sensed by
the upstream and downstream temperature sensors on the capillary depends on the amount of heat
absorbed by the gas flow.
The transfer function between gas mass flow and signal can be described by the equation:
Vsignal = output signal
cp= specific heat VKc
signal p m




K = constant factor
m= mass flow
The temperature sensors are part of a bridge circuit and the inbalance is linearised and amplified to the
desired signal level.
1.2.2 Gas flow sensors (direct mass flow measurement, CTA based)
The IN-FLOW CTA models operate on the principle of direct thermal mass flow measurement. The thru-flow
design sensor consists of a heater resistor and a temperature sensing resistor. Both resistors are made of
temperature sensitive resistive material that is covered with a stainless steel tube. The heating power
required to keep the temperature difference between the heater resistor and the sensing resistor at a
constant level is proportional to the mass flow. A different and unique heater current is produced for each
value of the flow. The measurement principle described is called Constant Temperature Anemometry (CTA).
The transfer function between mass flow and output signal can be described by the equation:
n
msignal KSS  0
Ssignal = output signal
S0= offset (zero flow) signal
K = constant factor (includes λ– heat conductivity, Cp– specific heat, μ– dynamic viscosity and ρ–
density of the gas)
m= mass flow
n = dimensionless constant (typically of order 0.5)
1.2.3 Liquid flow sensors
Two digital-liquid flow measurements and two sensor arrangements can be distinguished. They have in
common that there is no bypass system involved, which means that they are of the type: “thru flow”. The
following sensor arrangements can be distinguished:
1) The -FLOW model for flowrates up to 2 g/h.
Basically this is a small capillary tube with two sensing elements placed on the tube. The two elements both
serve as heater as well as temperature sensing elements. The delta-T sensed by the upstream and
downstream temperature sensors on the capillary depends on the amount of heat absorbed by the mass of
the liquid. The temperature sensors are part of a bridge circuit and the unbalance is amplified to the desired
signal level. The transfer function between liquid mass flow and signal can be described by the equation:
Vsignal = output signal
cp= specific heat VKc
signal p m




K = constant factor
m= mass flow

BRONKHORST®
9.17.022 page 13
2) The CTA based LIQUI-FLOW model for flow rates up to approximately 1000 g/h.
The CTA based LIQUI-FLOW model basically consists of a small capillary tube with two sensing elements
placed around it. The upstream sensing element is a temperature sensor that is used to measure the
temperature of the liquid flowing through the tube. The downstream sensing element is a heater, which is
heated up to a certain temperature T over the medium temperature. A patent application on the flow sensor
design has been submitted.
The heater power necessary to keep T at a constant level is dependent on the mass flow. In the case of no
flow, a constant and negligibly small heating power is necessary. When a certain mass flow occurs, the
heater is cooled down. Therefore, the heating power has to be increased to maintain the adjusted
temperature difference. Thus, a different and unique heater power is produced for each value of the flow.
The measurement principle described is called Constant Temperature Anemometry (CTA).
The heater and temperature sensing element are electrically connected via a Wheatstone bridge
configuration that performs two features: first, it provides the heater with the necessary heater power and
second, it takes care of the temperature compensation. Finally, a signal conditioning circuit provides a linear
output signal. The transfer function between the liquid mass flow and the linear output signal can roughly be
described with the equation:
Vsignal = output signal
K = calibration constant mpsignal cKV  2

cp= specific heat
= heat conduction coefficient
m= mass flow
1.2.4 Pressure sensor
The EL-PRESS pressure sensor is formed by a piezoresistive bridge on the surface of a silicon crystal.
The sensor is mounted in a stainless steel construction and separated from the fluid by a thin metal
membrane. The chamber around the sensor is filled with oil to couple the pressure from the fluid to the
sensor.
1.3 Valve principles
Control valves are not designed to provide positive shut-off, although some models have excellent
capabilities for this purpose.
It is recommended to install a separate shut-off valve in the line if so required. Also pressure surges, as may
occur during system pressurisation must be avoided. The following models can be distinguished:
1.3.1 Solenoid valve
This is considered to be the standard (direct operated) control valve. In
general it is a normally closed solenoid valve. The plunger is lifted by the
force of the magnetic field of the coil. The orifice under the plunger is
removable for optimising the orifice diameter. Also a normally opened
solenoid valve is available.
1.3.2 Vary-P valve
For process conditions where up- and downstream pressure
vary much, a special type of valve, VARY-P has been designed.
This valve consists of two valves, a solenoid operated control
valve and a fixed adjusted pressure compensation valve.
flowcontrol
valve
pressure
compensating
valve
flowcontrol
valve

BRONKHORST®
page 14 9.17.022
1.3.3 Pilot operated valve
For high flow rates the pilot operated valve has been designed. A
solenoid driven control valve controls the pressure difference
across a piston, which lifts the main plunger.
1.3.4 Bellows valve
This valve type is a direct driven, low power, solenoid operated control valve. A special design, incorporating
a metal bellows allows for a relatively large orifice opening to be controlled. The design is suited for low
pressure or vacuum applications.
1.4 Kv-value calculation
This calculation method can be used to determine the Kv-value of the main orifice of a control valve.
1.4.1 For gases
Determine desired p across valve.
p must be at least 20% of supply pressure, or in closed loop systems, of total pressure difference in loop.
If p is 20-50% of supply pressure, use formula:
KT
pp
v
vn n



514 2
undercritical
If P is 50-100% of supply pressure, use formula:
KpT
v
vn
n


257 1
overcritical
Units:
vn = flow [mn
3/h]
p1= supply pressure [bara]
p2= downstream pressure [bara]
p = pressure difference (p1- p2) [bara]
T = temperature [K]
n= density [kg/mn
3]
The orifice diameter can be determined by: d= 7.6 Kv[mm]
P1
pilot valve pressur
compensating
valve
P2
flowcontrol valve

BRONKHORST®
9.17.022 page 15
1.4.2 For liquids
This calculation method can be used to determine the Kv-value of the main orifice of a control valve.
Kp
vv
 

1000
Units:
v= volume flow [m3/h]
= density at 20°C and 1 atm [kg/m3]
p = delta p [bard]
The orifice bore diameter can be determined by:
[mm]7.6 v Kd 
On LFC's only one type of normally closed valve is available. Diameter of orifice can be calculated or looked
up in the table.
Diameter [mm] KvNormally closed
p max. [bard]
0,10
0,14
0,20
0,30
0,37
0,50
0,70
1,00
1,73 x 10-
4
3,39 x 10-4
6,93 x 10-4
1,56 x 10-3
2,37 x 10-3
4,33 x 10-3
8,48 x 10-3
1,73 x 10-2
10
10
10
10
10
10
10
10
* For liquids having a dynamic viscosity: 15 cP <

< 100 cP the Kvvalue should be calculated according to:
Kp
vv
 

1000
Units:
v= volume flow [m3/h]
= density at 20°C and 1 atm. [kg/m3]
p = delta p [bard]
= dynamic viscosity [cp]
For maximum possible viscosity apply to factory

BRONKHORST®
page 16 9.17.022
1.4.3 Maximum pressure drop
For (pilot) solenoid operated control valves with small orifices the maximum allowable pressure drop for
gases is according to the table.
Diameter [mm] KvNormally closed
p max. [bard]
Normally opened
p max. [bard]
0,05
0,07
0,10
0,14
0,20
0,30
0,37
0,50
0,70
1,00
1,30
1,50
1,70
2,00
4,33 x 10-
5
8,48 x 10-5
1,73 x 10-4
3,39 x 10-4
6,93 x 10-4
1,56 x 10-3
2,37 x 10-3
4,33 x 10-3
8,48 x 10-3
1,73 x 10-2
2,93 x 10-2
3,90 x 10-2
5,00 x 10-2
6,63 x 10-2
40
30
30
30
30
30
30
30
24
12
8
6
5
3,6
30
20
20
20
20
20
20
20
15
8
5
n.a.
n.a.
n.a.
For pilot operated valves the maximum pressure drop is limited to 20 bard. If the the pressure drop during
start-up is higher, it is prefered to install a bypass valve. During start-up this valve should be opened. Also
the minimum pressure drop is limited. For exact figures consult factory or proceed according to the technical
data and/or additional instructions given by the sales office or department.
1.5 Sensors and laminar flow devices
Flow devices are used to determine the total flow rate of a gas flow meter or controller.
Mind that liquid flow sensors, CTA-based sensors and pressure sensors do not require a flow device.
Depending on the application the flow sensors have different removable capillaries, requiring a different
laminar flow device.
Furthermore for flow rates higher than 1250 ln/min the main laminar flow device is used in combination with a
capillary / flow device arrangement in order to compensate for the non ideal transfer function of the main
flow device.
In general 3 types of capillary tubes are available:
- Small bore (C-type)
The following notes apply to this type of sensor:
- These sensors have a pressure drop of approx. 35 mbar
- The laminar flow device consists of a stack of discs with precision etched flow channels.
Each flow channel represents approx. 10 mln/min airflow at 35 mbar delta-P.
- In all instruments with a pressure rating above 100 bar (M-type) the sensor is fitted with metal
seals.
- In general instruments with these sensors may be mounted horizontal, as well as in a vertical
position, at low operating pressures. At high pressures (>10 bar) the instruments should be
mounted in a horizontal position.
- The EL-Flow, EL-press metal seal series are fitted with a metal sealed sensor.
- Large bore (D-type)
To this type of sensor the following remarks apply:
- These sensors are preferably used for reactive gases and at low pressure applications.
- The pressure drop is less than 0.5 mbar.
- The laminar flow device forms together with the main channel an annular channel. The dimensions
of this annular channel determine the flow capacity of the instrument.
- The instrument must always be mounted in a horizontal position.
- Medium bore (E-type)
This sensor is used in the “EL-FLOW series” and is used for increasing the flowrange of the “low deltaP
series”. The same remarks as the D-type apply to this sensor, only:
-The pressure drop is approx. 2.5 mbar.

BRONKHORST®
9.17.022 page 17
1.6 Conversion factors
1.6.1 Gas conversion factors (by-pass measurement)
The general formula for determining the relationship between signal and mass flow is:
VKc Kc
signal p m p v










in which:
V
signal = output signal
K = constant
= density
c
p= specific heat
m = mass flow
v= volume flow
As soon as the cp value and density of the gas to be metered change, the signal must be corrected. The
conversion factor C is:
Cc
c
p
p


1
2
1
2


in which:
c
p= specific heat
n= density at normal conditions
(1) gas calibrated
(2) gas to be measured
Note:
The cp value used for the calculation of the conversion factor must be taken at a temperature approx. 50°C.
higher than the required temperature.
This factor is called cp cal.
The conversion factors for commonly used gases related to N2at normal conditions are stated in the Gas
Conversion Table in the appendix 1.
Example:
Meter calibrated on N2(200 mln/min).
Gas flow passing the meter is CO2.
Output signal reads 80.0%.
Actual CO2 flow = 80.0 0.74
1.00 = 59.2%
so 59 2
100
.200 = 118.4 mln/min
* nmeans normal conditions
At normal conditions volumes are converted to a temperature of 0°C and pressure of 1 atm
or 1013,25 mbar. (760 Torr)
Note:
Best accuracy is always achieved by performing calibration under operating conditions. Should this not be
possible or practical, then the use of a theoretical conversion factor is a means to determine the flow rate of
the instrument on the gas to be metered, however, it will introduce inaccuracies.

BRONKHORST®
page 18 9.17.022
The approximate accuracy of the conversion factors listed is:
typical for conversion factors; > 1 2% x factor
<1
2% / factor
However, as the accuracy of the factor also depends on viscosity, pressure and temperature, special
attention should be taken for gases in the gas/liquid state where specific heat, density and viscosity can vary
tremendously. Apply to factory for more detailed information.
For gas mixtures a good approach is the following simplified equation:
11
1
2
2
C
V
C
V
C
mix
..... V
C
n
n
Cmix = Conversion factor for gas mixture
Cn= Conversion factor for gas n
Vn= Volumetric part of gas n in the mixture
Example Gas mixture contains:
(1) 10% N2C1 = 1,00
(2) 30% Ar C2 = 1,40
(3) 50% CH4C3 = 0,76
(4) 10% He C4 = 1,41
1010
100
030
140
050
076
010
141 1043 Cmix

,
,
,
,
,
,
,
,,
Cmix = 0,959
When the original meter has been calibrated on 500 mln/min N2, 100% means:
500
00,1
959,0
= 480 mln/min mixture.
When the original meter has been calibrated on 500 mln/min Argon, then 100% means:
500
40,1
959,0
= 343 mln/min gas mixture.
1.6.2 Gas Conversion Factors (direct mass flow measurement, CTA-based)
For CTA-based gas flow sensors the general relationship between signal and mass flow is:
n
msignal KSS  0
In which:
Ssignal = output signal
S0= offset (zero flow) signal
K = constant factor (includes λ– heat conductivity, Cp– specific heat, μ– dynamic viscosity
and ρ– density of the gas)
m= mass flow
n = dimensionless constant (typically of order 0.5)
Due to the offset signal (which is also dependent on fluid properties) and the non-linear relationship between
signal and mass flow, a single conversion factor for a custom fluid that covers the entire flow range of an
instrument can not be obtained. However, a complex and partially empirical conversion model is available for

BRONKHORST®
9.17.022 page 19
most common gases, which is accurate at both lower and higher flow ranges. Consult Bronkhorst®for
applications.
At nominal flow ranges for each instrument, a good approximation is the use of the so-called “CFDirect”
conversion method, which comes with the FLUIDAT software.
Consult FLUIDAT for the most optimal conversion factor.
1.6.3 Liquid Conversion Factors
1) -FLOW models
The general formula for determining the relationship between signal and mass flow reads:
in which:
Vsignal = output signal Vkc signal p m




k = calibration constant
cp= heat capacity at constant pressure of the fluid
m= mass flow
A conversion factor must be used if the liquid flow meter is not used on the calibrated liquid.
This conversion factor reads:
in which:
cp1 = heat capacity of the calibration liquid 12 mm Cf




Cf c
c
p1
p2

cp2 = heat capacity of the new liquid
For application of this formula consult Bronkhorst®
2) CTA based LIQUI-FLOW
For the CTA based LIQUI-FLOW liquid mass flow sensor, the transfer function between the liquid mass flow
and the linear output signal can roughly be described with the equation:
mpsignal cKV  2
Vsignal = output signal
K= calibration constant
cp= specific heat
= heat conduction coefficient
m= mass flow
A conversion factor must be used if the liquid flow meter is not used on the calibrated liquid (reference liquid)
but on another liquid (custom liquid). The conversion factor CF can roughly be calculated with the equation:



FLUIDCUSTOM
p
FLUIDREFERENCE
p
c
c
CF 2
2



For application of this equation, please consult Bronkhorst®
1.6.4 Software for conversion factor calculation
Bronkhorst®gathered the physical properties of over 600 fluids in a database called FLUIDAT.
Application software, such as FLUIDATon the Net (FOTN), enable the user to calculate accurate
conversion factors, not only at 20°C/1 atm (as shown in the conversion table, App.1) but at any
temperature/pressure combination.
Apply to your distributor for more details of this software.

BRONKHORST®
page 20 9.17.022
2 Installation
2.1 Receipt of equipment
Check the outside packing box for damage incurred during shipment. Should the packing box be damaged,
then the local carrier must be notified at once regarding his liability, if so required. At the same time a report
should be submitted to:
BRONKHORST HIGH-TECH B.V.
RUURLO HOLLAND
If applicable, otherwise contact your distributor.
Remove the envelope containing the packing list; carefully remove the equipment from the packing box.
Do not discard spare or replacement parts with the packing material and inspect the contents for damaged
or missing parts.
2.2 Return shipment
When returning material, always describe the problem and if possible the work to be done, in a covering
letter.
It is absolutely required to notify the factory if toxic or dangerous fluids have been metered with the
instrument!
This to enable the factory to take sufficient precautionary measures to safe-guard the staff in their repair
department. Take proper care of packing, if possible use the original packing box; seal instrument in plastic
etc.
All instruments must be dispatched with a completely filled in 'declaration on contamination form'.
Instruments without this declaration will not be accepted.
Note:
If the instruments have been used with toxic or dangerous fluids the customer should pre-clean the
instrument.
Important:
Clearly note, on top of the package, the customer clearance number of Bronkhorst High-Tech B.V., namely:
NL801989978B01
If applicable, otherwise contact your distributor for local arrangements.
2.3 Service
If the equipment is not properly serviced, serious personal injury and/or damage to the equipment could be
the result. It is therefore important that servicing is performed by trained and qualified service personnel.
Bronkhorst®has a trained staff of servicemen available.