Sierra RedyCompact Series User manual

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RedyCompact™ Series
Thermal Mass Flow Meters and Manual Regulators for Gases
RedyCompact™ Meter (GCM)
RedyCompact™ Regulator (GCR)
RedyCompact™Meter with Alarm Module (GSC)
RedyCompact™Regulator with Alarm Module (GCA)
Instruction Manual
Part Number: IM-RedyCompact
V1.Compact.EN A2-2

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Global Support Locations: We are here to help!
CORPORATE HEADQUARTERS
5 Harris Court, Building L Monterey, CA 93940
Phone [phone] [phone] Fax [phone]
[e-mail]
www.sierrainstruments.com
EUROPE HEADQUARTERS
Bijlmansweid 2 1934RE Egmond aan den Hoef
The Netherlands
Phone [phone] Fax [phone]
[e-mail]
ASIA HEADQUARTERS
Second Floor Building 5, Senpu Industrial Park
25 Hangdu Road Hangtou Town
Pu Dong New District, Shanghai, P.R. China
Postal Code 201316
Phone: + 8621 5879 8521 Fax: [phone]
[e-mail]
For Global Service Centers, go to http://www.sierrainstruments.com/facilities.html
© Copyright 2020 and Liability Disclaimer
All rights reserved. No part of this publication may be copied or distributed, transmitted, transcribed,
stored in a retrieval system, or translated into any human or computer language, in any form or by
any means, electronic, mechanical, manual, or otherwise, or disclosed to third parties without the
express written prior permission of Sierra Instruments.
The content of this manual is provided for information only and may be altered without prior notice.
Sierra Instruments assumes no responsibility or liability for any errors or inaccuracies in this manual.
For the latest information on our products, visit our website www.sierrainstruments.com
TRADEMARKS
RedyCompact™ and Redy™ is trademark of Sierra Instruments. Other product and company names
listed in this manual are trademarks or trade names of their respective manufacturers.

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Warnings and Cautions
“Warning,” “Caution,” and “Note” statements are used throughout this manual to draw your attention to important
information.
Symbol Key
Symbol
Symbol
Meaning
Descripition
Warning
“Warning” statements appear with information that is important to
protect people and equipment from damage. Pay very close
attention to all warnings that apply to your application. Failure to
comply with these instructions may damage the meter and
cause personal injury.
Caution
“Caution” indicates that failure to comply with stated instructions
may result in damage or faulty operation of the meter.
Note
“Note” indicates that ignoring the relevant requirements or
precautions may result in flow meter damage or malfunction.
Warning! Do not remove the electronics housing. A damaged hologram seal will void the warranty.
Warning! There are no serviceable parts inside the unit.
Warning! Repairs must only be performed by qualified personnel.
Warning! This unit has several power supply possibilities. If you use the external 24 VDC power
supply, it is strongly recommended to have this device grounded.

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Warning! Toxic, Flammable, Gases and ATEX: In the case of toxic and flammable gases, the
respective safety guidelines in each country must be followed. This Redy device is not Ex certified. In
the case of flammable and toxic gases, fittings, cable glands and pipes intended for that purpose must
be used. The responsibility for safe operation lies with the user and designer of the facilities.
Important Customer Notice- Oxygen Service
Sierra Instruments, Inc. is not liable for any damage or personal injury, whatsoever, resulting from the use
of Sierra Instruments standard mass flow meters or controllers for oxygen gas. You are responsible for
determining if this mass flow meter or controller is appropriate for your oxygen application. You are
responsible for cleaning the mass flow meter or controller to the degree required for your oxygen flow
application.
.
Warning! Power. If it becomes necessary to remove the instrument from the system or change a
battery, the power to the device must be disconnected. Always switch off the power before you
disconnect terminal connections in potentially dangerous surroundings to avoid sparks.
Note! Subject to Change: Due to our policy of ongoing product development, we reserve the right
to change the information in this manual without notice.

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RedyCompact™ Series Instruction Manual
This manual is for RedyCompact Series models:
•RedyCompact™ Meter (GCM)
•RedCompact™ Regulator (GCR)
•RedyCompact™ Meter with Alarm Module (GSC)
•RedyCompact™ Regulator with Alarm Module (GCA)
This manual is valid for instruments with a serial number greater than (>300000).
Receipt of System Components
When receiving a Sierra mass instrument, carefully check the outside packing carton for
damage incurred in shipment. If the carton is damaged, notify the local carrier and submit
a report to the factory or distributor. Remove the packing slip and check that all ordered
components are present. Make sure any spare parts or accessories are not discarded
with the packing material. Do not return any equipment to the factory without first
contacting Sierra Customer Service.
Technical Assistance
If you encounter a problem with your flow meter, review the configuration information for
each step of the installation, operation, and setup procedures. Verify that your settings
and adjustments are consistent with factory recommendations. Installation and
troubleshooting information can be found in this manual. See Chapter 3 for installation
and Chapter 6 for troubleshooting.
If the problem persists after following the troubleshooting procedures outlined in the
RedySmart product manual, contact Sierra Instruments by fax or by E-mail (see inside
front cover). For urgent phone support you may call [phone] or [phone]
between 8:00 a.m. and 5:00 p.m. PST. In Europe, contact Sierra Instruments Europe at
[phone]. In the Asia-Pacific region, contact Sierra Instruments Asia at + 86-21-
58798521. When contacting Technical Support, make sure to include this information:
• The flow range, serialnumber, andSierra order number (all marked on
the meter nameplate)
• The software version (visible at start up)
• The problem you are encountering, and any corrective action taken
• Application information (gas, pressure, temperature and piping
configuration)
This manual is updated for the latest firmware version of the red-y compact 2. Please verify
that your unit is updated with firmware version 3.0.6 available from our website (see chapter
5.12 Firmware upgrade).

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Recycling
Note the existing regulations of your country.
Register Your Product Today
Three (3) Year Warranty (Sierra MEMS Therma Mass Flow Sensor: RedySmart and
RedyCompact Brands)
All Sierra products are warranted to be free from defects in material and workmanship and will be
repaired or replaced at no charge to Buyer, provided return or rejection of product is made within a
reasonable period but no longer than three (3) years for calibration and non-calibration defects,
from date of delivery.
To assure warranty service, customers must register their products online on Sierra’s website.
Online registration of all of your Sierra products is required for our warranty process. Read
complete warranty policy at www.sierrainstruments.com/warranty.
Lifetime No-Drift Sensor Warranty
Sierra Mems Thermal Mass Flow Products
In addition to Sierra’s standard three (3) year manufacturing warranty on all MEMS mass flow
instruments produced, Sierra also offers a Lifetime No-Drift Sensor Warranty. Sierra defines no-
drift as less than 1% of full scale over the life of the instrument. Therefore, if drift of greater than
1% of full scale occurs over the sensor’s lifetime, the sensor and/or entire instrument will be
repaired or replaced and recalibrated free of charge.
This warranty applies to all MEMS/CMOS thermal mass flow sensors standard on every Sierra
RedySmart™ and RedyCompact™ models sold after January 15, 2020. This warranty is only valid
if the unit is exclusively used with the gas or gases specified during the initial calibration or
recalibration, without any additives in any form and under the operating conditions (temperature,
inlet and outlet pressure, full scale flow rate) the unit was originally specified for.
Sierra’s Lifetime No-Drift Sensor Warranty is made possible due to high-precision MEMS (Micro-
Electro Mechanical Systems) technology utilizing an advanced ultra-stable CMOS (Complementary
Metal Oxide Semiconductor) sensor. The use of MEMS techniques allows both electronic circuits
and mechanical devices to be manufactured on a silicon chip, similar to the process used for
integrated circuits.
Learn more about Sierra’s Lifetime No-Drift Sensor Warranty at
www.sierrainstruments.com/warranty or see detailed lifetime no-drift sensor warranty in Appendix
8.
Register Warranty Online
Register now at www.sierrainstruments.com/register. Learn more about Sierra’s warranty policy at
www.sierrainstruments.com/warranty .

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Table of contents
Register Your Product Today 6
1. Introduction 9
1.10. Features of RedyCompact Thermal Mass Flow Meters 9
1.11. Scope of Warranty 9
1.12. Instructions and Warnings 10
1.13. Documentation and Cables Supplied 11
1.14. The Measurement Principle 11
1.15. Real, Standardized and Normalized flow 12
1.16. CMOS technology 13
1.17. Block Diagram 14
2. General device specifications 15
2.10. Safety 16
2.11. Electrical Data for Meter GCM and Regulator GCR 16
2.12. Measurement Ranges (air) 16
2.13. USB Interface 17
2.14. Battery 17
2.15. Optional Modules 18
2.16. Calibration 19
2.17. Operation with Other Gases 19
2.18. Pressure Loss 20
2.19. Temperature Compensation 20
2.20. Pressure Compensation 20
2.21. Response Time 20
2.22. Filter settings 21
3. Installation and Commissioning 22
3.10. Mounting Position and Mounting Location 22
3.11. Requirements for Pipework 22
3.12. Fittings and Filters 23
3.13. Filters / Gas Cleanliness 23
3.14. Electrical Power Supply 24
3.15. How to replace the battery? 25
3.16. Warm-up time 26
4. Operation 27
4.10. Introduction 28
4.11. Main Menu 34
4.12 Settings 43
5Maintenance 50
5.10. Cleaning to Remove Contamination 50
5.11. Returns 51

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5.12. Firmware Upgrade 52
6. Troubleshooting 54
6.10. Pressure Loss 55
6.11. Dimensional Drawings ¼” In mm 58
6.12. Dimensional Drawings ¼” In Inches 59
6.13. Dimensional Drawings ½” In mm 60
6.14. Dimensional Drawings ½” In Inches 61
6.15. Type Code Overview 62
6.16. Wetted Parts RedyCompact Series 63
6.17. Overview Default Settings 64
7. Overview Menu RedyCompact 67
8. Detailed Warranty Statement for RedySmart & RedyCompact Brands 70
9. Index 72

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1. Introduction
Thank you for choosing devices from the RedyCompact™Series. These operating instructions will
help you to install and operate these gas flow measuring devices. Please read through these
instructions carefully before installing the unit. Our aim has been to write a full and practical guide.
We would be grateful if you would notify us of any shortcomings or mistakes.
Please contact Sierra Instruments” Customer Service if you have questions about any aspect of
the product (s), you may call [phone] or [phone] between 8:00 a.m. and 5:00
p.m. PST. In Europe, contact Sierra Instruments Europe at [phone]. In the Asia-Pacific
region, contact Sierra Instruments Asia at + 86-21-58798521.
The RedyCompact is a thermal based mass flow meter that can measure the mass flow of gases.
The core element of the red-y thermal mass flow meter is a CMOS sensor chip. The sensor and
parts of the electronics are on one board and offer a number of advantages for the user.
1.10. Features of RedyCompact Thermal Mass Flow
Meters
In developing and manufacturing the devices, we have focused primarily on customers and their
applications. Our aim is to implement customers' requirements in the form of new developments or
enhancements on an ongoing basis. The essential features are:
•Compact design
•Battery operated optional (Portable)
•Dot-matrix LCD touch screen
•Multiple gases possible (3 gases)
•Flexible due to the many different settings accessible through the touch screen
•Back-light screen in USB and 8…30 VDC power mode
•Power also possible with USB micro-B connector or external 8…30 VDC (Separate
module)
•Optional alarm module with power, 3 contacts and 2 inputs
•Display can be rotated 180 degrees
•Fast and accurate measurement and control
•Integrated temperature compensation and flow totalizer (standard)
•Easy to maintain and service
•Firmware upgradable through USB connection
•3-year warranty
1.11. Scope of Warranty
Warranty for the RedyCompact product line extends to material and manufacturing defects only.
Maximum warranty covers product replacement free of charge. The following causes of
faults/damage are not covered under warranty:
•Use outside the operating limits
•Damage due to corrosion
•Damage due to leaking batteries
•Mechanical damage in general

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•Contamination due to improper sealing
•Contamination due to impure gases or penetration of liquids
•Damage to electronic components due by over-voltage or electrostatic discharges, and
corrosion damage due to aggressive environments
•Functional failure due to incorrect operation or faulty parameterization
•If the unit has been opened or otherwise tempered with
•Drift in the calibration
•EEPROM damage
1.12. Instructions and Warnings
Read all of the operating instructions thoroughly before installing and commissioning equipment.
Misconceptions and incorrect use can lead to breakage of the measuring device or risk of personal
injury. Should one of these cases occur, the responsibility lies solely with the operator of the
device.The installation, commissioning and operation and maintenance must be done by
appropriately qualified personnel.
1.12.1 Installation
It is recommended that the user check the devices on a regular schedule to ensure that it is leak
free as both metal and elastomer seals, gaskets, o-rings and valve seats may change with age and
exposure to process gas.
1.12.2 Power
If it becomes necessary to remove the instrument from the system or change a battery, the power
to the device must be disconnected. Always switch off the power before you disconnect terminal
connections in potentially dangerous surroundings to avoid sparks.
Important Note
Please note before the start-up:
•Do not use sealing tape or liquid sealant
•Piping must be cleaned before installation of instrument
Warning!
Products in this manual may contain metal or elastomer seals, gaskets, o-
rings or valve seats. It is the “user’s” responsibility to select materials that
are compatible with their process and process conditions. Using materials
that are not compatible with the process limitations of the device, may
result in equipment damage and/or personnel injury or death.

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1.13. Documentation and Cables Supplied
A printed quickstart quide is shipped together with each device. However, we recommend to visit
our website to obtain the latest version of the manual and the latest firmware version for the
RedyCompact.
Every device comes with a USB A to USB Micro-B cable. This cable can be used to power the unit
and to upgrade the firmware.
We ship the device with the following accompanying documentation:
•1 factory calibration certificate per ordered calibration
•Final inspection report
•USB cable + 1 x AA battery (if battery powered)
•Quick Install Guide
•Product Information Card with links to current instruction manual
1.14. The Measurement Principle
The thermal mass flow measurement principle is particularly suitable for the measurement and
control of clean and dry gaseous media. The most significant advantage is that the measurement
process measures the real mass flow and is largely independent of temperature and pressure.
Stated simply, the thermal measurement principle measures the heat transport by gas flowing past.
In the case of red-y mass flow measuring instruments, a constant heat input gives a flow-
dependent temperature difference (∆T). Two temperature sensors are positioned in the measuring
channel (T1, T2), one before the heating system (H) and one after it (see Figure 1).
If there is no flow, the heat spreads symmetrically in directions T1 and T2. The temperature
difference T1-T2 is therefore zero.
Flow rates > 0 create a temperature difference. The sensor T1 at the inlet is cooled by the gas
flowing past it, and the temperature of the second sensor T2 rises due to the heat drawn from the
heating system.
Figure 2: Measurement Principle
Figure 1: Sensor Operation

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The temperature difference is related non-lineary to the mass flow, with very high repeatability. The
electronics will, based on the calibration, convert this temperature difference in a linear and
proportional indication of the mass flow of the gas.
1.15. Real, Standardized and Normalized flow
The user-selectable engineering units of the RedyCompact has been divided in two groups: “Real
and Normal” units and “Other units.”
This separation is not only there to find the unit you want to select quicker, it also separated the
“Normalized flow” from the “Standardized flow.”
Figure 3: Units Menu
The RedyCompact has basically two reference conditions: One for “Real and Normal” units and
one for “Other units.”
The factory setting is as follows:
1) For all units that are used in "normal" (like ln/min), the reference conditions are always 0°C
and 1013.25 mbara. This cannot be adapted.
2) For all the other units that are “standard” (like ls/min and sccm) and the l/min the reference
conditions has to be be defined when the unit is ordered.

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The reference value for all units that are not “Normal” or “Real” it has to be defined with the
purchase order. It cannot be changed after the units has been delivered.
On the label of the RedyCompact we will mention a reference condition. This reference condition is
for the “Standard” units only. The “normal” units will always be 0°C and 1013.25 mbara.
In future version of the firmware the reference conditions will be adjustable in the menu.
Gas flow in general can be expressed in one of the following:
•Volumetric Flow: (f.i. l/min). This theoretically cannot be measured by the RedyCompact
because it is volume. The RedyCompact measures mass flow. However, due to regional
requirements we still have it as a flow unit that is selectable. Units shown as volume (l/min)
refer to the customer defined reference conditions (Same as “standard”).
•Real Mass Flow: (f.i. kg/h). This refers to true mass units per time unit. The RedyCompact
can measure this and you can select this type of unit from the menu.
•Normalized Volumetric Flow: Normalized means that the units are “translated” to
predefined pressure and temperature conditions. Normalized or Normal Conditions refers to
0°C and 1013.25 mbar absolute. You can select this type of unit from the menu of the
RedyCompact. These units are mostly used in Europe and China.
•Standardized Volumetric Flow: Standardized means that the units are “translated” to
predefined pressure and temperature conditions. Standardized or Standard conditions
refers to 20°C (68°F) and 1013.25 mbar (=760 mmHg) absolute. You can select these type
of units from the menu of the RedyCompact. These units are mostly used in the USA.
Standardized can also refer to other reference conditions (f.i. Natural Gas industry often
uses 15°C and 1013.25 mbar absolute. In the semicon world they often use 25°C and
1013.25 mbara. Please define and mention these reference condition at the time of your
order.
1.16. CMOS technology
The Redy measuring and control devices are equipped with an innovative CMOS semiconductor
sensor that sets new standards for accuracy, speed and measurement dynamics.
With our CMOS technology the sensor element, amplifier and A/D converter form a single silicon
chip.
Important Note
Please note that reference condition relating to Normalized or Standardized
volumetric flow are not the operating conditions. According to the ideal gas
law, the gas volume will change by 0.35% per K.
Important Note
Please note that Sierra standard uses the following densities for their main
3 gasses: Air: 1.293 gr/m3, N2: 1.2504 gr/m3, O2: 1.429 gr/m3 (All at 0°C
and 1013.25 mbar absolute). If you use other densities or need additional
information for other gasses, please contact the factory. Densities need to
be defined before manufacturing and cannot be adjusted once the unit has
been delivered.

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1.17. Block Diagram
The following GCM block diagram shows the structure of the device. The block diagram does not
show the optional manual control/needle valve (model GCR) that would normally be placed on the
outlet of the unit.
Turbulence
filter By-pass
Touch Display
(dotmatrix 128x64 Px) Micro processor
EEPROM
USB
Interface
Power
conditioning
Sensor
Figure 4: Block Diagram

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2. General device specifications
Media (real gas calibration): Air, O2*, N2*, He, Ar, CO2, H2, CH4, C3H8
(other gases and gas mixtures on request)
*O2& N2are calibrated with air.
Accuracy:
Eco
±2.0% of full scale; Ranges > 200 ln/min ±3.0% of full scale
Special
±1.0% of full scale (only G¼” instruments and real gas calibrations)
Dynamics:
Eco
1:50 (Meter reads zero if flow is less than 1.7% of full scale)
Special
1:100 (Meter reads zero if flow is less than 0.83% of full scale)
Response Time
Maximum 300 msec (filter setting dependend)
Flow Update By Sensor
40 ms (Battery mode 500 ms)
Display Update
240 ms (Battery mode 500 ms)
Repeatability
±0.5% of full scale
Long-Term Stability
< 1% of reading / year
Temperature Coefficient
< 0.025% FS measuring range type per °C
< 0.012% FS measuring range type per 1°F
Pressure Coefficient
< 0.2% / bar of reading (typical N2)
< 0.014% / psi of reading (typical N2)
Working Pressure Range
0.2 - 11 bara (3-160 psia)
Test Pressure
16 bara (232 psia)
Storage Conditions
-20 to 80°C (-4 to 176°F), 0-95% RH, non-condensing
Temperature Range
0 –50°C (32 bis 122°F), 0-95%, RH, non-condensing
Warning: Do not expose device to direct sun light.
Warm-Up Time
< 5 sec. for full accuracy
Materials
Electronics Housing
ABS (Acrylnitril-Butadien-Styrol)
Body Material
Anodized aluminium or stainless steel 1.4404 (316L)
Sensor Area
Silicon, glass, epoxy
Seal Material
FKM, optional EPDM (FDA compatable)
Wetted Parts
See appendix (see chapter 6.17 Wetted Parts List)
Integration
Display
Touch display 128x64 px
Backlighted only with external power supply (Micro-USB or 24 VDC )
Process Connection
G¼" (BSPP* female) up to 60 ln/min,
G½" (BSPP* female) up to 450 ln/min
*British Standard Pipe Parallel
Inlet Section
None required
Mounting Orientation
Any position (consult manufacturer above 5 bara (72 psia) if the
RedyCompact will be mounted vertical)
Connection Cable
For external power supply: 2 m with loose ends (fly leads)

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2.10. Safety
Test Pressure:
16 Bara (232 psia)
Leak rate to external:
1 x 10-6 mbar*l/s He
Protection class:
IP-50
EMC
EN 61326-1
2.11. Electrical Data for Meter GCM and Regulator
GCR
Supply Voltage
Power supply RedyCompact meter & regulator Standard AA
battery or USB micro-B power supply (DIN 62684)
Option: External power 8...30 VDC , 120 mA. We recommend a
power supply with a minimum current of 150 mA.
(Power supply hereafter refered to as the 24 VDC power
supply)
2.12. Measurement Ranges (air)
The RedyCompact has four different flow elements available. Each element has a defined
maximum operating flow range that will be defined during calibration. The flow ranges selectable
below are the maximum flow ranges for air/O2and N2only. For other gasses consult the factory.
These ranges are adjustable electronically during factory configuration to your desired full scale
range.
Type Measurement full scale (air), scale freely selectable
RedyCompact Meter GCx: GCx-A from 50 mln/min to 600 mln/min
GCx-B from 600 mln/min to 6000 mln/min
GCx-C from 6 ln/min to 60 ln/min
GCx-D from 60 ln/min to 450 ln/min

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2.13. USB Interface
The unit has a female USB micro-B connection (DIN 62684) that can be used as an external power
supply and to upgrade the firmware. USB micro-B is the same connector you find on older Android
and Windows portable phones, you can use the charger of your telephone to power the
RedyCompact.
Note
It is not possible to read data from the flow meter through the USB
connection.
2.14. Battery
The battery operated RedyCompact can operate on any common AA battery. The lifetime is
strongly dependent on the usage and the quality of the battery. In general we can state that the
battery lasts for about 3-6 months under non-continuous use (see Notes below).
We recommend to use external power (USB micro-B or 24 VDC ) if you application needs
continuous measurement like measuring totalized flow. To extend the lifetime of the battery, the
back-light is disabled during battery operation, you cannot activate it. We strongly recommend to
use the “auto power off”in the menu for battery driven devices (see chapter 4.12.7 Battery auto off)
More information on the battery in chapter 3.15 Electrical power supply and 3.16 How to replace
the battery?.
Note
When we supply the unit, the “auto power off” will be set to 15 minutes.
Note
The unit can be set to performance mode when powered from the
battery, this will strongly increase the battery usage. See chapter 4.12.1
Measurement for more information.

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2.15. Optional Modules
As an additional option you can purchase a power supply or an alarm module.
2.15.1 Power Supply Module
The power supply module, is provided with a voltage from 8-30 VDC , will power the unit. The
unit comes with a 2-meter cable.
2.15.2 Alarm Module
The alarm module provides three
individually settable alarms and two inputs.
Each alarm can be set by the customer. The
module is supplied with a 2-meter fly-lead
cable and needs to be powered by 8-30 VDC
which also powers the RedyCompact flow
meter.
Each of the 3-alarm contacts can be
configured as high, low, window and totalizer
alarm. Once the alarm becomes active, the
three potential free alarm contacts can be
reset in many different ways. Automatic,
through the touch screen or with one of the
two input signals. Other options like
hysteresis settings and delays (timers) are
also available.
The two input contacts or customer set alarm
conditions can also be used to reset the
totalizer.
For detailed information see 4.11.2 Alarm
Menu in this manual.
Power in

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Note
Both the power and the alarm module are mounted similar to the
battery module (see 3.16 How to replace the battery). They replace the
battery module, so you cannot use these modules in combination with
battery power.
Warning
An external magnet can unintentionally influence the alarm contacts.
Generic Specifications Optional Alarm Module GCA
Power Input
Voltage Supply Range : 8-30 VDC (Power supply hereafter refered to as the 24 VDC power
supply)
Maximum Current : 300 mA
Protection input: Polyfuse (trip current > 500mA) and reverse polarity protected
Switch Ratings Switch 1 + 2 (SPST hard contact)
Maximum Current
0.5 A
Maximum Voltage
30 VDC
Relais Lifetime
> 5 million
Switch ratings switch 3 (DPST contact)
Maximum Current
1 A
Maximum Voltage
30 VDC
Relais Lifetime
> 5 million
Inputs 1 + 2 (Opto-couplers)
Voltage Range (polarity sensitive): 5 –30 VDC (@ 5mA max)
Min. Recommended Pulse Width
100 msec (Sample interval: 20 msec)
2.16. Calibration
Each measuring device is supplied with a factory calibration report. The calibration is traceable to
American and/or European standards. On request we can also provide DAkkS calibration (German
Accreditation Body).
2.17. Operation with Other Gases
Each measuring device can store data for up to 3 types of gas or operational states that need to be
defined at the time of purchase.
CMOS gas flow sensors are not linear (The output is linearized) and respond different to each gas.
If the gas or gas composition is different than the gas that the unit was calibrated for, the unit will
not measure accurately. It is possible to program up to three different gases and gas mixtures, but
this needs to be done at the factory or at a Sierra Instruments’ certified calibration center. Please

20
note that the K-factors as used in the traditional capillairy MFM/MFC cannot be used for CMOS
mass flow meters. Please contact the factory for additional information.
2.18. Pressure Loss
Our thermal mass flow meters have a low pressure drop. The pressure drop depends mainly on
the medium, the pressure conditions and the flow rate. In chapter 6.11 Pressure Loss you find the
pressure drop for the most common gases. Your sales partner has a calculation program for the
other gases. Please note that the size of the pipes has a large effect on the pressure loss. For
example from around 60 ln/min, we recommend a pipe inside diameter of at least 10 mm.
Caution
Please also note that some fittings have a reduced diameter and can
cause considerable pressure drop in your system. Be especially careful
with vacuum applications, please select a relative big pipe diameter).
2.19. Temperature Compensation
The RedyCompact thermal mass flow meters measure the mass flow of gases, the result being
largely independent of pressure and temperature. In addition to the fundamental principle an
internal sensor measures the gas temperature and, with the help of a 3-dimensional table of
interpolation values, a correction factor is calculated automatically. The flow indication is thus
temperature-compensated.
2.20. Pressure Compensation
During calibration, the specified operating pressure is taken into account. Changes to the pressure
conditions may introduce an additional error. This is around ±0.2% per bar.
Please note that the control behavior is influenced by substantially different pressure conditions.
This is relevant for units with an intergrated needle valve only.
2.21. Response Time
The response time is time required to display 98% of its final value after a sudden change in flow.
This response time for the RedyCompact is around 300 ms but is dependent on your filter settings.
On battery operation you might experience a slower response time than on external power. (See
chapter 4.12.1 Measurement for more information.
Note
Please note that, among other effects, the zero-point error (offset
display) will be higher if the device is not operated with the type of gas,
for which it had been calibrated. A difference in zero indication is also
possible if the used pressure is different than specified.