SENSIRION SFC54 Series User manual

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Engineering guidelines for Mass Flow Controllers
(SFC5xxx) and Mass Flow Meters (SFM5xxx)
Summary
This guide provides recommendations for evaluation, testing and integration of Sensirion Mass Flow Controllers and
Meters. It is applicable to SFC55xx, SFC54xx, SFC53xx as well as SFM55xx, SFM54xx and SFM53xx products.
For clarity, the document was written for Mass Flow Controllers, yet most guidelines are also valid for Mass Flow Meters.

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Contents
1. How to choose your Mass Flow Controller (Mass Flow Meter)........................................................................................................... 3
2. How to operate your Mass Flow Controller................................................................................................................................................. 3
2.1. Digital interface ..................................................................................................................................................................................... 3
2.2. Analog interface.................................................................................................................................................................................... 4
3. Testing recommendations................................................................................................................................................................................... 4
4. Common pitfalls ...................................................................................................................................................................................................... 5
4.1. Flow appears to be off by several %............................................................................................................................................. 5
4.2. Settling time is longer than specified .......................................................................................................................................... 5
5. Design recommendations ................................................................................................................................................................................... 5
5.1. Pressure drop and input pressure ................................................................................................................................................. 5
6. Fluidic and electrical connectors ...................................................................................................................................................................... 6
6.1. Downmount interface......................................................................................................................................................................... 6
7. Recalibration Tool................................................................................................................................................................................................... 7
8. Useful resources ...................................................................................................................................................................................................... 8
8.1. Documentation...................................................................................................................................................................................... 8
8.2. Software tools ......................................................................................................................................................................................10
8.2.1. Viewer and Recalibration software .......................................................................................................................10
8.2.2. Software drivers ............................................................................................................................................................10
8.3. Calibration, lifetime and FAQ ........................................................................................................................................................10

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1. How to choose your Mass Flow Controller (Mass Flow Meter)
Sensirion offers several families of Mass Flow Controllers and Meters.
•SFC5500 (SFM5500) is ideal for first testing and projects with yearly volumes up to 50 pieces. It is available in fixed
configurations with pre-configured multiple gas calibrations, different flow ranges, exchangeable fittings and
available via distribution.
•SFC54xx (SFM54xx) family is a make-to-order product and offers the highest configurability (flow rates, fluidic
connectors, and communication interfaces), and suitable for projects of various sizes.
•SFC53xx (SFM53xx) product family are Sensirion’s OEM Mass Flow Controllers (Mass Flow Meters) best suited for
projects with yearly volumes above 50 pieces.
To help you choose the right Mass Flow Controller, a “Selection guide”is available on the Sensirion website. Please see
“Useful resources” section below.
2. How to operate your Mass Flow Controller
The evaluation method depends on whether your Mass Flow Controller has a digital or an analog interface.
2.1. Digital interface
Several different ways to operate Sensirion digital Mass Flow Controllers exist. They vary in complexity and implementation
flexibilities.
The EK-F5x evaluation kit is the fastest way to start working with your Mass Flow Controller. It combines a power supply
(adapters for most sockets worldwide are included) and a USB-A plug for your PC. It is a simple plug-and-play system to
evaluate all digital Mass Flow Controllers with a DB9 plug (an adapter is available for other plugs –please contact Sensirion).
EK-F5x is available from distribution. Please note, Mass Flow Controller is not included and has to be purchased separately.
•The quickest way to start working with your device is using the EK-F5x evaluation kit together with Sensirion
Viewer Software. It is a plug-and-play solution, which will enable you to control and configure your device (e.g.
choose the gas calibration). The Viewer Software can be used to control multiple Mass Flow Controllers by opening
several instances of the program on a single PC.
•Another simple way to control your device is to use the evaluation kit together with the available LabVIEW drivers.
This allows for more flexibility at an expense of some implementation effort. A LabVIEW implementation is suitable
to most laboratory and prototyping applications. It is possible to control multiple Mass Flow Controllers with a
single LabVIEW program, by giving the devices different addresses.
•Most OEM projects will require designing custom cabling (including a power supply) together with an
implementation in the desired programming language. Sensirion provides ready-to-use libraries in C, C# and
Python (see Section 8.2.2 in Useful Resources). These libraries can be used to control multiple devices at the same
time (please make sure the devices have unique RS485 addresses) or to add the Mass Flow Controllers to a
measurement sequence. However, this also involves the highest implementation effort out of the options
mentioned here.
It is also possible to use LabVIEW library with custom cabling, or to use C, C# and Python libraries with EK-F5x evaluation
kit.

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Table 1 Software options for evaluating digital Mass Flow Controllers
2.2. Analog interface
To operate a Mass Flow Controller with an analog interface (SFC54XX), you need:
•a tuneable power supply as setpoint source, being able to deliver 0-5V, 0-10V or 4-20mA, depending on the
version of the analog Mass Flow Controller
•a DB9 cable to connect the Mass Flow Controller to a 15-24V power supply
•a multimeter or an oscilloscope to measure the flow signal
3. Testing recommendations
It is recommended to start by testing the communication with the device, using the EK-F5x Evaluation Kit and the Viewer
software. The baud rate and address of the device with the viewer software can easily be changed if necessary.
As a second step, connect the device to a gas supply (or a source of vacuum). For best accuracy, mount the Mass Flow
Controller horizontally and use the same pressure as during factory-calibration (specified in the datasheet, by default for
most products 3 bar inlet vs outlet).
If the Mass Flow Controller is mounted vertically, the chimney effect can adversely impact the accuracy at low flows and
especially at zero flow. It is possible to use Sensirion recalibration software to compensate for that effect. The “Recalibration
software” can be downloaded from the Sensirion website and is also linked in the “Useful resources” Section 8.1. In this
case, you will have to calibrate the mass flow controller yourself in the chosen orientation.
Try using different setpoint steps to test the Mass Flow Controller. If the chosen setpoint can’t be reached, try increasing
the supply pressure, removing fluidic resistances like filters, or using tubes with a larger diameter. If the supply pressure
used is significantly lower than the calibration pressure, the controller can be slower than expected. On the other hand, if
the supply pressure is significantly larger than the calibration pressure, the Mass Flow Controller may become unstable. In
these cases, lowering or increasing the user gain to adapt the controller accordingly. This can be done conveniently with
the Viewer Software. For detailed instructions, see the “Viewer Software Manual”, linked in “Useful resources” Section 8.2.1.
SFC5xxx/SFM5xxx Viewer software
LabVIEW +
C/C#/Python library
for quick evaluation
plug-and-play software
no coding required
no custom cabling required
for more flexible testing and prototyping
custom coding required
custom cabling recommended for C/C#/Python
Figure 1 Different options for evaluating digital Mass Flow Controllers

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4. Common pitfalls
4.1. Flow appears to be off by several %
If the flow appears to be off by several % (especially around 7%) against your reference, there are good chances the flow
units of the two devices are not the same. Sensirion’s Mass Flow Controllers can be factory calibrated for different units:
e.g. standard or norm litres. The conversion difference between the two is around 7%, due to the different reference
temperatures used for standard and norm litres. Please make sure that the Mass Flow Controller and your reference are
using the same units when testing. Further information about the flow unit conversion can be found in a dedicated
application note, “Reference and Flow Conversions between mass and volumetric flow”, in the “Useful resources” Section
8.1.
4.2. Settling time is longer than specified
The most common cause for observing longer than expected settling time is trying to verify it from a position of fully closed
valve. Solenoid valves are commonly affected by so-called “stiction effect”. To open the valve from closed position (setpoint
0), a certain overvoltage is required to overcome the stiction effect. This can lead to a spike in the flow (especially for low
setpoints) or a longer than expected settling time. By adjusting the “user gain” of the Mass Flow Controller, the behaviour
can be tuned to the specific requirements.
The settling time of Sensirion’s Mass Flow Controllers is specified for a step answer from 10% to 100% of full scale within
5% of setpoint. When testing the settling time, do not do so from a position of zero flow.
5. Design recommendations
To achieve best accuracy, it is recommended to use a design where the Mass Flow Controller is mounted horizontally.
The valve used in the Mass Flow Controllers (proportional valve) is an oscillating system. Try to avoid sources of vibrations
or decouple these sources mechanically from the Mass Flow Controller. They can interfere with the proper function of the
valve.
The operation of the valve produces a significant amount of heat. The Mass Flow Controller should therefore not be placed
in a hermetically sealed space. It is recommended to design a cooling flow over the Mass Flow Controller in order to
counteract the heating from the valve. Large temperature gradient between the Mass Flow Controller and the gas it is used
to control, may adversely influence the accuracy of the device.
5.1. Pressure drop and input pressure
Pressure drop is generated when gas passes through the valve of a mass flow controller. The magnitude of the pressure
drop is proportional to the flow rate and the density of the gas.
It is important to verify that at the maximum required flow rate, for a given gas, the inlet pressure is higher than the pressure
drop. If this cannot be achieved, contact Sensirion –it might be possible to order a similar mass flow controller with larger-
sized valve. Larger valves offer a lower pressure drop at the cost of a decreased accuracy/resolution at low flows.

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6. Fluidic and electrical connectors
Table 2 Fluidic and electrical connectors
Product reference
Fluidic connector
Electrical
connector
SFC5500/
SFM5500
Factory fitted with Legris
G ¼’’ flange (exchangeable fittings)
Compatible with Legris, Swagelok, Festo, Serto fittings (and others)
DB9
SFC5400/
SFM5400
Swagelock, VCO, VCR, Downmount
DB9
SFC5460/
SFM5460
Swagelock, VCO, VCR, Downmount
JST 4-pin*
SFC5300/
SFM5300
Downmount
DB9
SFC5330/
SFM5330
Downmount
JST 4-pin*
*Please ask Sensirion for an adapter, if used with EK-F5x evaluation kit.
6.1. Downmount interface
When using products with downmount connectors, a specific manifold must be designed and manufactured by the user.
In Table 4 in the “Useful resources” Section 8.1, CAD models for a suggested manifold designs for SFC54xx / SFM54xx and
SFC53xx / SFM53xx can be found. They can be used as a starting point for a custom design.
The required O-rings for sealing are not provided by Sensirion. Suggestions are provided in the Table 4 in “Useful resources”
Section 8.1. It is recommended to use the same sealing materials as inside the Mass Flow Controller (see datasheet) to
ensure material compatibility with the used gasses.
Description of the manifolds:
•SFx54xx: 4 screws can be used for mounting. The O-rings must be placed on the mass flow controller side. The
manifold pictured below can be used as a starting point for the design. A Mass Flow Controller is placed on top
of the manifold.
Figure 2 Suggested manifold design for SFC54xx / SFM54xx

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•SFx53xx: for the short body-type (see datasheet) 2 screws are needed for fixation from the bottom side. For the
long body 4 screws can be used from the top. The O-rings must be placed on the manifold side. The design
pictured below is compatible with both “short” and “long” body designs.
7. Recalibration Tool
Sensirion’s MEMS-based Mass Flow Controllers are shipped fully calibrated for the gasses specified when ordering. Unlike
traditional, capillary-type Mass Flow Controllers, they do not drift and do not require regular re-calibration.
However, it is also possible to create and save a custom calibration for special use cases. A dedicated tool is available for
this purpose. Possible scenarios, where user re-calibration might be helpful are:
•calibrate the Mass Flow Controller for gases, for which the controller was not factory calibrated
•calibrate the Mass Flow Controller at a pressure significantly different than factory calibration conditions (typically
3 bar differential pressure: 4 bar at inlet and atmospheric pressure at outlet)
•any situation which leads to the factory calibration requiring adjustments due to the accuracy requirements, e.g.
vertical instead of horizontal implementation, …
To recalibrate your Mass Flow Controller, you need a source of pressurized gas with defined flow rate and the Sensirion
recalibration software. To precisely measure the flow through the Mass Flow Controller, it is recommended to set up the
Mass Flow Controller in series with a Mass Flow Meter as a reference (see picture). The number of calibration points will
impact the accuracy of the calibration. Generally, fewer points are needed when the new calibration gas has similar
properties (density, thermal conductivity and heat capacity) compared to one of the gasses the mass flow controller has
already been factory calibrated for. An example would be re-calibrating a device for O2which has already been factory
calibrated for Air.
The software tool and its manual can be downloaded from the Sensirion website. A link to “SFC5xxx/SFM5xxx Viewer
software” is provided in the “Useful resources” Section 8.2.1.
Figure 3 Suggested manifold design for SFC53xx / SFM53xx
Figure 4 Recommended configuration for re-calibration of Mass Flow Controllers

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8. Useful resources
8.1. Documentation
Various guides and application notes are available on Sensirion website.
Mass Flow Controllers (SFC): sensirion.com/products/product-categories/mass-flow-controllers/
Mass Flow Meters (SFM): sensirion.com/products/product-categories/gas-flow-sensors/
General technical download section: sensirion.com/products/downloads/
The most relevant resources are linked below.
Selection guide
Quick start guide
SFC5500 gas fittings guide
SHDLC Communication Interface Reference

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Reference and Flow Conversions between mass and
volumetric flow
Introduction video: SFC5500 Mass Flow Controllers
Table 3 Datasheets, CAD models and O-ring recommendations
Product
reference
Datasheet
CAD model
Downmount
manifold
CAD model
Downmount
recommended
O-ring
SFC5500/
SFM5500-
200slm
sensirion.com/resource
/datasheet/sfc5500
sensirion.com/resource
/cad/sfc5500-200
SFC5500/
SFM5500-
50sccm
0.5slm
2slm
10slm
sensirion.com/resource
/cad/sfc5500
SFC5400/
SFM5400
sensirion.com/resource
/datasheet/sfc5400
sensirion.com/resource
/cad/sfc5400
sensirion.com/media/d
ocuments/Mounting_p
late_SFX54xx.step
NORMATEC O-ring
FKM NT 80.7/75 OR
2019 inner Ø 4,76 x
1,78 mm
SFC5460/
SFM5460
https://sensirion.com/r
esource/datasheet/sfc5
460_sfm5460
https://sensirion.com/r
esource/cad/downmou
nt_SFC5460_SFM5460
SFC5300/
SFM5300
sensirion.com/resource
/datasheet/sfc53x0_sf
m53x0
sensirion.com/resource
/cad/sfc5300
sensirion.com/media/d
ocument/Mounting_pl
ate_SFX53xx
Defined by the design
of the manifold
(customer)
SFC5330/
SFM5330

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8.2. Software tools
8.2.1. Viewer and Recalibration software
SFC5xxx/SFM5xxx Viewer software
sensirion.com/media/documents/Sensirion_Mass_Flow_Controllers_SFC5xxx_Viewe.zip
SFC5xxx/SFM5xxx Viewer Software manual
sensirion.com/media/documents/GF_AN_SFC5xxx_Viewer_D1.pdf
SFC5xxx/SFM5xxx Recalibration software
sensirion.com/media/documents/SFC5xxx_SFM5xxx_RecalibrationTool_V1_72.msi
SFC5xxx/SFM5xxx Recalibration software manual
sensirion.com/resource/user_guide/recalibrationtool/sfc5xxx/sfm5xxx
8.2.2. Software drivers
Python driver
github.com/Sensirion/python-shdlc-sfc5xxx
LabVIEW, C and C# drivers
sensirion.com/media/documents/SFC5XXX_Sample_Code.zip
8.3. Calibration, lifetime and FAQ
Thanks to the stability of the MEMS-based sensor element and the robust mechanical design, Sensirion Mass Flow
Controllers do not drift and do not require recalibration in the field.
High manufacturing standards used during production ensure that our Mass Flow Controllers are extremely reliable and
have a very low failure rate. This is supported by field surveys and measurements.
Mean time between failures of Sensirion devices has been found to be 169 years. The detailed analysis based on several
thousand parts in the field can be found in a dedicated application note:
sensirion.com/resource/application_note/mean_time_between_falilure_analysis
The high-quality valves used are rated for 100 million cycles. The EEPROM memory of the MFC is rated for 50 000 write
cycles. This de-facto limits the number of times a calibration, user gain etc can be changed. Please take this into
consideration, when implementing the Mass Flow Controller.
FAQ:
sensirion.com/products/support/faq/

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Important Notices
Warning, Personal Injury
Do not use this product as safety or emergency stop devices or in any other application where failure of the product could result in
personal injury. Do not use this product for applications other than its intended and authorized use. Before installing, handling, using
or servicing this product, please consult the data sheet and application notes. Failure to comply with these instructions could result in
death or serious injury.
If the Buyer shall purchase or use SENSIRION products for any unintended or unauthorized application, Buyer shall defend, indemnify and
hold harmless SENSIRION and its officers, employees, subsidiaries, affiliates and distributors against all claims, costs, damages and
expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such
unintended or unauthorized use, even if SENSIRION shall be allegedly negligent with respect to the design or the manufacture of the
product.
ESD Precautions
The inherent design of this component causes it to be sensitive to electrostatic discharge (ESD). To prevent ESD-induced damage and/or
degradation, take customary and statutory ESD precautions when handling this product.
See application note “ESD, Latch up and EMC” for more information.
Warranty
SENSIRION warrants solely to the original purchaser of this product for a period of 12 months (one year) from the date of delivery that
this product shall be of the quality, material and workmanship defined in SENSIRION’s published specifications of the product. Within such
period, if proven to be defective, SENSIRION shall repair and/or replace this product, in SENSIRION’s discretion, free of charge to the
Buyer, provided that:
•notice in writing describing the defects shall be given to SENSIRION within fourteen (14) days after their appearance;
•such defects shall be found, to SENSIRION’s reasonable satisfaction, to have arisen from SENSIRION’s faulty design, material, or
workmanship;
•the defective product shall be returned to SENSIRION’s factory at the Buyer’s expense; and
•the warranty period for any repaired or replaced product shall be limited to the unexpired portion of the original period.
This warranty does not apply to any equipment which has not been installed and used within the specifications recommended by
SENSIRION for the intended and proper use of the equipment. EXCEPT FOR THE WARRANTIES EXPRESSLY SET FORTH HEREIN, SENSIRION
MAKES NO WARRANTIES, EITHER EXPRESS OR IMPLIED, WITH RESPECT TO THE PRODUCT. ANY AND ALL WARRANTIES, INCLUDING
WITHOUT LIMITATION, WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE EXPRESSLY EXCLUDED AND
DECLINED.
SENSIRION is only liable for defects of this product arising under the conditions of operation provided for in the data sheet and proper
use of the goods. SENSIRION explicitly disclaims all warranties, express or implied, for any period during which the goods are operated or
stored not in accordance with the technical specifications.
SENSIRION does not assume any liability arising out of any application or use of any product or circuit and specifically disclaims any and
all liability, including without limitation consequential or incidental damages. All operating parameters, including without limitation
recommended parameters, must be validated for each customer’s applications by customer’s technical experts. Recommended parameters
can and do vary in different applications.
SENSIRION reserves the right, without further notice, (i) to change the product specifications and/or the information in this document and
(ii) to improve reliability, functions and design of this product.
Copyright © 2021, by SENSIRION. CMOSens® is a trademark of Sensirion. All rights reserved
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