Models: 820, 820S, 822, 822S, 824, 824S, 826 and 827
Instruction Manual
Part Number IM-82
Revision H, November 2017
Page 2
Table of Contents Series 820 Instruction Manual
GLOBAL SUPPORT LOCATIONS: WE ARE HERE TO HELP!
CORPORATE HEADQUARTERS
5 Harris Court, Building L Monterey, CA 93940
Phone (831) 373-0200 (800) 866-0200 Fax (831) 373-4402
www.sierrainstruments.com
EUROPE HEADQUARTERS
Bijlmansweid 2 1934RE Egmond aan den Hoef The Netherlands
Phone +31 72 5071400 Fax +31 72 5071401
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: +8621 5879 8586
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 ma ss 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
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 me ans,
electronic, mechanical, manual, or otherwise, or disclosed to third parties without the express written permission of Sierra Instruments. The information contained in this manual is subject to change
without notice.
TRADEMARKS
Top-TrakTM and Cal-Bench TM is a Registered Trademark of Sierra Instruments, Inc. Other product
and company names listed in this manual are tradem arks or trade names of their respective manufacturers.
Returning Equipment to the Factory ....................................... 4-13
3-1
IM-82 0-3
Page 4
Table of Contents Series 820 Instruction Manual
Appendix A Conversion Formulas and Gas Tables
Appendix B 822/824 Product Specifications
Appendix C 822S/824S Product Specifications
Appendix D 826/827 Product Specifications
List of Figures
1-1. Top-Trak Features (Typical) ........................................ 1-3
1-2. Flow Paths through the Transducer ............................. 1-4
Only qualified personnel should install the transducer.
Do not supply +DC power at the D-connector while using a
power supply at the power jack. Both supplies may be damaged.
Caution!
Operating a 12 VDC transducer at 24 VDC will cause equip-
ment damage.
Caution!
Only qualified personnel should perform transducer service, ca-
libration or troubleshooting procedures.
Caution!
When using toxic or corrosive gases, purge the unit thoroughly
with inert dry gas before disconnecting from the gas line.
Caution!
Printed circuit boards are sensitive to electrostatic discharge. To
avoid damaging the board, follow these precautions to minimize the risk
of damage:
before handling the assembly, discharge your body by touching
a grounded, metal object
handle all cards by their edges unless otherwise required
when possible, use grounded electrostatic discharge wrist
straps when handling sensitive components
IM-82 0-5
Page 6
Page 7
Series 820 Instruction Manual Chapter 1 Introduction
Chapter 1 Introduction
This instruction manual covers the installation, operation and
maintenance of Sierra’s 820 Series product line including the following Top-Trakª Models:
822 Mass Flow Meter with display (nylon flow body)
824 Mass Flow Meter without display (nylon flow body)
826 Hi-Flow Meter with display (aluminum flow body)
827 Hi-Flow without display (aluminum flow body)
822-S Mass Flow Meter with display (stainless steel flow body)
824-S Mass Flow Meter without display (stainless steel flow body)
Sierra’s Top-Trakª Mass Flow Meters are designed for precise
measurement of gas mass flow. The 820 Series offers a broad
range of sizes and process connections for flexibility and versatility. The primary standard calibration ensures starting point accuracy and NIST traceability. The meter’s 0-5 VDC or 4-20 mA output
signal is provided for recording, data-logging or control. The optional display reads the mass flow rate directly in engineering units
or percentage of full scale.
Using This Manual
This manual is organized into four chapters:
Chapter 1 includes the introduction and theory of operation
Chapter 2 provides installation and wiring instructions
Chapter 3 describes transducer operation and features
Chapter 4 covers maintenance, calibration and troubleshooting
IM-82 1-1
Gas tables and conversion formulas are found in Appendix A.
The product specifications and dimensional drawings are found
in Appendix B.
Throughout this manual, we use the word
transducer
as a generic term to represent all models of Sierra’s 820 Series TopTrak Mass Flow Meters.
Page 8
Chapter 1 Introduction Series 820 Instruction Manual
Safety Information
Caution and warning statements are used throughout this book to
draw your attention to important information.
Warning! Caution!
This statement appears with information that
is important to protect people and equipment
from damage. Pay very close attention to all
warnings that apply to your application.
Receipt of System Components
When receiving a Sierra transducer, 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 and match your specifications (as ordered).
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.
This statement appears with information that is
important for protecting your equipme nt and
performance. Read and follow all cautions that
apply to your application.
Technical Assistance
If you encounter a problem with your transducer, review the configuration information for each step of the installation, operation and
set up procedures. Verify that your settings and adjustments are
consistent with factory recommendations. Refer to Chapter 4,
Troubleshooting, for specific information and recommendations.
If the problem persists after following the troubleshooting procedures outlined in Chapter 4, contact Sierra Instruments by fax or by
E-mail (see inside front cover). For urgent phone support you may
call (800) 866-0200 or (831) 373-0200 between 8:00 a.m. and 5:00
p.m. PST. In Europe contact Sierra Instruments bv at +31 20
6145810. When contacting Technical Support, make sure to include
this information:
the flow range, serial number, Sierra order number and
model number (all marked on the transducer nameplate)
the problem you are encountering and any corrective action
taken
application information (gas, pressure, temperature, pipe
and fitting configuration)
1-2 IM-82
Page 9
Series 820 Instruction Manual Chapter 1 Introduction
Top-Trak Features
Standard Top-Trak Mass Flow Meters require a 12 to 15 VDC external power source (24 VDC input power optional). The transducer’s 0 to 5 VDC output signal allows for flow recording, data-logging
or control. A 4 to 20 mA output signal is optionally available. Input
power and output signal connections are made via the 9-pin subtype D-connector located on the side of the transducer. An additional input power jack is located just below the D-connector. (It is
important to connect input power at only one location.)
The transducer shown below is a typical example of a 822 Series
Top-Trak Mass Flow Meter. Other models may vary slightly in
their appearance but are operationally equivalent.
IM-82 1-3
Figure 1-1. Top-Trak Features (Typical)
Page 10
Chapter 1 Introduction Series 820 Instruction Manual
The 820 Series Flow Sensing Principle
The operating principle of Top-Trak transducers is based on heat
transfer and the first law of thermodynamics. During operation
process gas enters the instrument’s flow body and divides into two
flow paths, one through the sensor tube, the other through the laminar flow element bypass. The laminar flow bypass generates a
pressure drop, P1–P2, forcing a small fraction of the total flow to
pass through the sensor tube (m1).
Figure 1-2. Flow Paths through the Transducer
Two resistance temperature detector (RTD) coils around the sensor
tube direct a constant amount of heat (H) into the gas stream. In
actual operation, the gas mass flow carries heat from the upstream
coil to the downstream coil. The resulting temperature difference
(?T) is detected by the RTD coils and gives the output signal.
Since the molecules of the gas carry away the heat, the output signal is linearly proportional to gas mass flow.
Figure 1-3. Flow Measuring Principle
1-4 IM-82
Page 11
Series 820 Instruction Manual Chapter 2 Installation
Chapter 2 Installation
Installation Overview
To ensure a successful installation, inlet and outlet tubing should be clean
and free from burrs or rims caused by cutting prior to plumbing the transducer into the system. The protective caps covering the inlet/outlet fittings
should not be removed until immediately prior to installation.
Before installing the transducer, verify the following:
1. Make sure the installation site meets the specific operating parameters
recorded on the transducer’s nameplate. Each transducer is factoryconfigured for a specific gas and flow range. If the operating pressure is
more than 50 psi (3.4 bar) away from the calibration pressure, it is advisable to return the unit to the factory for re-calibration. (Adjusting zero
may be sufficient to remain within specification.)
2. Do not locate the transducer in areas subject to sudden temperature
changes, moisture, drafts or near equipment radiating significant amounts
of heat. Make sure to allow adequate space for cable connectors and wiring.
3. For 1/2-inch size inlet/outlet process connections on models 826 and 827
make sure the location meets the minimum number of recommended pipe
diameters upstream and downstream of the transducer. A minimum of 5
inches (127 mm) upstream and 2-1/2 inches (64 mm) downstream is always recommended. (not necessary for other models)
4. Horizontal mounting is preferable. Vertical mounting is possible with
best results achieved when the factory calibration is specifically performed for vertical mounting. In vertical positions zero shift will occur
depending on the gas pressure at zero flow.
5. If the gas contains any particulate matter, install an in-line filter prior to
the transducer. Recommended filter size: 15 micron for flows of 10
sccm to 30 slpm, 30 micron for above 30 slpm.
6. If a potential over-flow condition exists, insert a valve or critical orifice
in the line to limit flow to approximately 25 percent above the full scale
range of the meter.
7. Confirm that the transducer o-ring material is compatible with the gas to
be measured.
8. For remote displays, confirm the supplied cable is of sufficient length to
connect the components.
IM-82 2-1
Page 12
Chapter 2 Installation Series 820 Instruction Manual
Installing the Transducer
Follow the installation instructions that apply to your transducer’s
Caution!
Only qualified personnel
should install the
transducer.
process connection. For all 1/2-inch size process connections, observe
the piping recommendations given on page 2-3. Before operation, all
plumbing should be checked carefully for leaks and the transducer
purged with dry nitrogen.
Compression Fittings
1. Position the transducer with the flow direction arrow pointing
downstream in the direction of flow.
2. Verify the position of the front
and back ferrule. Insert the
tubing into the fitting. Make
sure that the tubing rests firmly
on the shoulder of the fitting
and that the nut is finger tight.
(Do not mix or interchange
parts of tube fittings made by different manufactur- ers.)
3. Hold the body steady with a backup wrench.
tighten the nut 1-1/4 turns from finger tight. For 1/8-inch, 1/4- inch
and 3∕8-inch sizes, tighten only 3/4 turn from finger tight.
over-tighten!
4. Check the system’s entire flow path thoroughly for leaks. (Do not
use liquid leak detectors, instead monitor pressure decay. Overexposing the transducer to leak detector fluid may damage the unit.)
For 1/2-inch size,
Do not
VCO Fittings
1. Position the transducer with the flow direction arrow pointing
2. Install new o-rings compatible with the gas to be used. (Do not mix
3. Hold the body steady with a backup wrench.
4. Check the system’s entire flow path thoroughly for leaks. (Do not use
2-2 IM-82
downstream in the direction of flow.
or interchange parts of tube fittings made by different manufacturers.)
Tighten the nut
finger tight and then 1/4 turn tighter with a wrench.
tighten!
Do not over-
liquid leak detectors, instead monitor pressure decay. Over- exposing
the transducer to leak detector fluid may damage the unit.)
Page 13
Series 820 Instruction Manual Chapter 2 Installation
1/4 inch Female NPT Connections
1. Position the transducer with the flow direction arrow pointing in the direction of flow.
Use a good quality paste pipe thread sealant. Apply to pipe threads.
2.
3. Tighten the pipe no more than 1 turn past hand-tight. Caution! Do not
over-tighten. Damage to the instrument may result.
1/2-Inch Size NPT Connections
1. Install a section of straight pipe at least ten pipe diameters in length up-
stream of the transducer. Also, allow at least five pipe diameters downstream for accurate operation. DO NOT use reducers. If the preceeding
components in the flow path create disturbances extend the upstream pipe
length.
2. Position the transducer with the flow direction arrow pointing down-
stream in the direction of flow.
3. Tighten fittings until leak tight (refer to published standards for specific
recommendations).
(standard on nylon flow bodies
)
4. Check the system’s entire flow path thoroughly for leaks. (Do not use liq-
uid leak detectors, instead monitor pressure decay. Over-exposing the
transducer to leak detector fluid may damage the unit.)
Figure 2-1 Piping Requirements for all 1/2-Inch Size Process Connections
IM-82 2-3
Page 14
Chapter 2 Installation Series 820 Instruction Manual
r
e
t
Caution!
Do not supply +DC powe
at the D-connector whil
using a power supply a
the power jack. Both sup-
plies may be damaged.
Caution!
Operating a 12 VDC trans-
ducer at 24 VDC will cause
equipment damage.
Wiring the Transducer
Standard Top-Trakrm transducers require a 12 to 15 VDC power supply
(15 VDC nominal, 100 mA maximum). 24 VDC input power is
optional. Transducers are connected to the power supply through
either
the dedicated DC power jack or through the 9-pin D-connector
located on the side of the enclosure. Before powering the unit, check
the transducer’s nameplate to confirm input power:
PV1 = 12 to 15 VDC
PV2 = 24 VDC
Note: operating a 24 VDC transducer at 12 to 15 VDC will result in unreliable
operation.
The transducer’s standard 0 to 5 VDC (4-20 mA optional) output sig- nal is
available through the D-connector. The mating connector is in- cluded with the
transducer. Connection details are given on the fol- lowing pages.
When the transducer is configured for a remote display, signal connections are made via the 9-pin connector. Input power connections
are not included in the standard interface cable. Power connections
for the display and the transducer are shared when the connector is
wired for a remote display. Optionally the input power can be applied
at the power jack (either 12 volts (PV 1) or 24 volts (PV2). Remote
display mounting dimensions are given at the end of this chapter.
2-4 IM-82
Page 15
Series 820 Instruction Manual Chapter 2 Installation
Note: The power jack requires a plug that has a 2.5mm inner diameter and a 5mm outer
diameter. The center is positive (+).
IM-82 2-5
Page 16
Chapter 2 Installation Series 820 Instruction Manual
Standard 0-5 VDC Output Signal Wiring
The standard 0-5 VDC output signal flows from Pin 3 (0-5 VDC Out)
through the load (1K Ohm minimum) to Pin 7 (Power Common). The
figure below is a typical example of input power and output signal
connections.
Figure 2-3. Standard 0-5 VDC Output Signal Wiring
Optional 4-20 mA Output Signal Wiring
The optional 4-20 mA output signal flows from Pin 9 (4-20 mA Out)
through the load (50 to 500 Ohms maximum) to Pin 7 (Power Common). The figure below is a typical example of input power and output
signal connections. (Multiple transducer current loop output connections are given on the next page.)
Figure 2-4. Single Transducer Current Loop Connection
2-6 IM-82-E
Page 17
s
Series 820 Instruction Manual Chapter 2 Installation
Figure 2-5. Multiple Transducer Current Loop Connection
Remote Display Installation
Mount the remote display at a convenient location within reach of the
supplied interface cable. The maximum cable length is 100 feet (30 m).
IM-82 2-7
Figure 2-6. Mounting the Remote Display
Page 18
Page 19
Series 820 Instruction Manual Chapter 3 Operation
Chapter 3 Operation
The output signal of the transducer is either 0-5 VDC (standard) or
4-20 mA (optional). The output signal is linear and proportional to
the gas mass flow rate. For example, for a 0-5 VDC output signal,
5.00 VDC is the output signal for the full scale listed on the transducer’s nameplate, 2.50 VDC is for one-half of full scale, and 0.00
VDC is for zero flow. For a 4-20 mA output signal, 20.00 mA is
the output signal for the full scale, 12.00 mA is for one-half of full
scale, and 4.00 mA is for zero flow.
Transducer Operation
When the transducer is installed and the system has undergone a
complete leak check:
1. Apply power. The output signal will be at a high level for the
first 10 to 20 seconds while the sensor warms up to its normal
operating temperature range. Assuming zero flow, the output
signal will then drop to zero (or 4 mA, depending on output
configuration). Allow at least thirty minutes of warm-up time.
2. For first-time start ups, perform an initial zero output check as
described on page 3-3. After checking the initial zero setting,
the transducer is ready to monitor the gas mass flow rate.
Transducer Accuracy
The standard accuracy of Top-Trak is ±1.5% of full scale. The
±1.5% of full scale accuracy means that the 0-5 VDC output signal is accurate to within ±.075 VDC. The 4-20 mA output is accurate to within ±0.24 mA.
For example, the output signal for zero flow can be as much as
±.075 VDC or +0.24 mA. If the transducer has an output signal at
zero flow, as long as it is within either of these two ranges, it does
not mean it is malfunctioning.
For transducers with a digital display, the accuracy is simply .015
times the full scale flow rate stated on the nameplate. For example, if the full scale is 10 slpm, the digital display will be accurate
to ±0.15 slpm. The reading at zero flow may be as much as +0.15
slpm and still be within the stated accuracy specification.
IM-82 3-
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Page 20
Chapter 3 Operation Series 820 Instruction Manual
Referencing the Transducer to Non-Standard Conditions
The gas flow rate output of your transducer is referenced to
“normal” conditions of 21 °C (70°F) and 760 mm of mercury (1
atmosphere) unless otherwise specified on the certificate of
calibration. Check the stated reference conditions of your transducer.
If you are comparing your transducer’s output with another type of flow
meter, different reference conditions could cause a discrepancy
between the flow readings.
For example, the output reading of a Top-Trak will be approximately
7% lower when referenced to 0°C rather than 21°C. To find the flow
rate referenced to other standard conditions or the actual temperature
and pressure conditions in the pipe where your transducer is located,
see Appendix A.
Transducer Over-Ranging
If the flow rate exceeds the full scale value listed on the transducer
nameplate, the output signal and digital display (if so equipped)
will read a higher value. The transducer is not calibrated for overranged flows and will probably be both non-linear and inaccurate.
Over-range conditions are indicated by the display and/or output
signal going to a level above the full scale range. When the overrange condition is removed, it may take several seconds for the
transducer to recover and resume normal operation.
If the supply voltage is only 12 VDC, the over-ranged reading may
exceed the full scale value by 10% maximum. If the supply voltage
is higher, as with the 24 VDC option, then the output can exceed
the full scale by as much as 50%, or more. Digital displays cannot
exceed 3-1/2 digits (1999). If the flow rate exceeds 1999, the rightmost digits will blank and only the left-hand “1” will appear on the
display.
3-2 IM-82
Page 21
Series 820 Instruction Manual Chapter 3 Operation
Zero and Span Adjustments
The zero and span potentiometers are
accessed through the ports marked on
the side of the transducer. Normally,
span adjustments are not made unless
you are calibrating the transducer. The
span adjustment should not be used
unless you have a known, precise nonzero flow rate that you wish to match.
Before making any zero adjustments,
confirm that the system has reached its
normal operating temperature and
pressure and the transducer is mounted
in its final position.
For transducers without the digital display:
1. Power the transducer and allow at least 30 minutes of warm up
time before attempting any adjustments. Set gas flow to zero.
Confirm that no flow exists.
2. Connect a digital multimeter to Pin 3 (0-5 Out) or, Pin 9 (4-20 Out)
and Pin 7 (Power Common). Check the reading. If it does not
indicate 0± .05 VDC, (or 4.0± .016mA) adjust the zero potentiometer.
Since the output signal does not indicate negative numbers, it is
necessary to adjust down from a slightly positive reading. Begin by
slowly rotating the zero pot clockwise until a positive reading is
indicated. To complete the zero adjustment, slowly turn the pot
counterclockwise until zero is achieved, or to the point where out- put
quits changing (may be slightly above zero point in some cas- es) DO
NOT ADJUST DOWNWARD BEYOND THIS POINT.
For transducers with the digital display:
1. Power the transducer and allow at least 30 minutes of warm up
time before attempting any adjustments. Set gas flow to zero.
Confirm that no flow exists.
2. Observe the reading on the digital display. If the reading is
greater than 1.0% of full scale, adjust the zero potentiometer.
IM-82 3-
3
Page 22
Chapter 3 Operation Series 820 Instruction Manual
820 Totalizer Operation
The optional 820 totalizer is designed to provide a totalizer function within the digital display of the 820 series. It will display the
flow rate, the total flow or both at once. If your instrument has this
option, it is described below. Note the flow units and the totalizer
units are pre-set at the factory and must be the same.
Screens:
The totalizer display has three screens which are accessed by
pressing the button circled in the photo below:
Screen 1
(start-up screen shown in photo above): Flow units are
shown together with the actual flow
Screen 2
Screen 3
: Totalized flow in the same units as Screen 1 above
: Actual flow is shown together with the total flow
Totalizer:
A total of 8 digits can be shown by the totalizer ranging from
.0000001 to 99999999. The decimal point will automatically shift
position as the total increases. Upon reaching the maximum count
(99999999), the totalizer will “roll-over”--be cleared and begin
counting from zero again.
The totalizer may be cleared by going to screen 2 or 3 and then
pressing the button for more then 5 seconds. The clearing of the totalizer can be observed on the screen.
The total count is saved in non-volatile memory every 5 minutes.
If the unit is switched off within 5 minutes from power-up then no
total will be saved and the previous total will be shown at the next
power-up.
Caution:
happen that during power up the screen remains blank. If this occurs, please turn the unit off and then back on again
Due to the combination of the hardware/LCD, it may
3-4 IM-82
Page 23
Series 820 Instruction Manual Chapter 4 Maintenance and Repair
Caution!
It is important that this
transducer be serviced
and/or calibrated by
qualified personnel.
Chapter 4 Maintenance and Repair
Top-Trakm transducers essentially require no scheduled maintenance other than periodic flow path cleaning if the gas is dirty. If an
in-line filter is used, the filtering element should be periodically
replaced or ultrasonically cleaned.
CAUTION: If the laminar flow element is removed from any TopTrakm flow meter, re-calibration will be required to return the instrument to original accuracy.
Calibration of Sierra Instruments flow meters and controllers requires a calibrating standard of at least equal accuracy and preferably an order of magnitude better than the transducer, and a skilled
factory technician familiar with the Top-Trak. It is recommended
that Top-Trak meters be returned to the factory for annual evaluation and calibration.
Included in this chapter are general instructions for:
Returning Equipment to the Factory ....................... page 4-12
Transducer Cleaning
Due to transducer design variations, separate cleaning instructions
are given in this chapter for each of the following models:
Model 822/824 with nylon flow body
Model 826/827 with aluminum flow body
Model 822-S/824-S with stainless steel flow body
When toxic or corrosive gases are used, the transducer must be
thoroughly purged with inert dry gas before disconnecting from the
gas line. Transducers used with toxic or corrosive gases SHOULD
NOT BE returned to the factory since they constitute a safety hazard. Contact the factory with specific questions.
IM-82 4-
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Page 24
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t
Chapter 4 Maintenance and Repair Series 820 Instruction Manual
Flow Path Cleaning Model 822/824
Figure 4-1. Model 822/824 Flow Components
Caution!
When using toxic or cor
rosive gases, purge the
unit thoroughly with iner
dry gas before disconnecting from the gas line.
Inlet and Outlet Screens
1. Remove the transducer from the system.
2. Remove inlet and outlet fittings.
3. Pull out the laminar flow element (LFE) holddowns.
4. Replace or clean the inlet and outlet screens.
5. Re-assemble components. When the transducer is installed in
the system, leak test the connection.
6. To be within the original accuracy, calibrate the transducer (see
page 4-9).
4-14 IM-82
Page 25
Series 820 Instruction Manual Chapter 4 Maintenance and Repair
Laminar Flow Element
The laminar flow element (LFE) is a precision flow divider which
Caution!
the LFE from the
meter will change
your calibra- tion.
the LFE unless you are
prepared to re-calibrate
Removing
Do not remove
the instrument.
diverts a preset amount of flow through the sensor tube. The particular LFE used depends on the gas and flow range of the instrument. To clean or inspect the LFE:
1. Remove the transducer from the system.
2. Remove the inlet and outlet fittings and inlet screen.
3. The LFE has a slightly tapered shape with the larger diameter
on the upstream (inlet) side. To remove, use a blunt object
which does not mar the flow channels to push the LFE from the
outlet side to the inlet side. A 3/8-inch (9 mm) nut driver works
well.
4. Clean the LFE using an alcohol-based solvent. Make sure to
carefully clean all active flow channels in the LFE.
5. Re-install the LFE making sure to press it in the correct distance as shown below.
6. Re-assemble remaining components. When the transducer is
installed in the system, leak test the connection. Re-zero the
transducer (see Chapter 3).
7. Calibrate the instrument (see page 4-9).
IM-82 4-
Figure 4-2. Correct LFE Position
3
Page 26
Chapter 4 Maintenance and Repair Series 820 Instruction Manual
Flow Path Cleaning Model 826/827
Caution!
the LFE from the
meter will change
your calibra- tion.
the LFE unless you are
prepared to re-calibrate
Removing
Do not remove
the instrument
.
Laminar Flow Element
The laminar flow element (LFE) is a precision flow divider which
diverts a preset amount of flow through the sensor tube. The particular LFE used depends on the gas and flow range of the instrument. To clean or inspect the LFE:
1. Remove the transducer from the system.
2. Remove the 6-32 hex nuts and washers. Remove the end caps. Note
the position of the three (3) LFE elements.
3. To remove the LFE, use a blunt object which does not mar
the flow channels to push the LFE from the flow body.
4. Clean the LFE using a suitable solvent. Make sure to carefully
clean all active flow channels in the LFE.
5. Re-install the LFE making sure to position it with both ends
even with the transducer flow body.
6. Re-assemble remaining components. When the transducer is
installed in the system, leak test the connection. Re-zero the
transducer (see Chapter 3).
7. Perform a calibration (see page 4-9).
Figure 4-3. Model 826/827 Flow Components
4-4 IM-82
Page 27
Series 820 Instruction Manual Chapter 4 Maintenance and Repair
Flow Path Cleaning Model 822-S/824-S
Caution!
the LFE from the
meter will change
your calibra- tion.
the LFE unless you are
prepared to re-calibrate
Removing
Do not remove
the instrument
.
Laminar Flow Element
The laminar flow element (LFE) is a precision flow divider which
diverts a preset amount of flow through the sensor tube. The LFE
is made of precision machined 316 stainless steel. The particular
LFE used depends on the gas and flow range of the instrument.
Should the LFE require cleaning or inspection due to deposition,
use the appropriate cleaning procedure which is specific to flow
body size.
Figure 4-4. Low Flow Transducer LFE Cleaning
Low Flow Transducers:
The LFE is accessed by unscrewing the main inlet fitting and removing it from the flow body. The LFE is screwed into the inlet
fitting, which has been specially machined for this purpose. To
access the components:
1. Remove the transducer from the system.
2. The inlet filter screen is held in place in the inlet fitting by the
.
LFE. Disassemble by holding the fitting steady with a wrench
and unscrewing the LFE with a medium flat-tipped screwdriver.
IM-82 4-
3. Remove the LFE assembly taking care not to bend the inlet
screen. Inspect the sealing O-ring and replace if necessary. Inspect the inlet screen and replace if corroded or damaged. Light
to medium particulate contamination can be cleaned by back
washing with a suitable solvent. Air dry thoroughly.
5
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Chapter 4 Maintenance and Repair Series 820 Instruction Manual
4. Inspect the LFE for damage and replace if necessary. Remember
that removal or replacement of the LFE or inlet screen requires
transducer re-calibration.
5. Re-assemble components. When the transducer is installed in
the system, leak test the connection. Re-zero the transducer
(see Chapter 3).
6. To be within the original accuracy, calibrate the transducer (see
page 4-9).
Caution!
the LFE from the
meter will change
your calibra- tion.
the LFE unless you are
prepared to re-calibrate
Removing
Do not remove
the instrument.
Figure 4-5. Medium Flow Transducer LFE Cleaning
Medium Flow Transducers:
In the medium flow body, the LFE assembly consists of the honeycomb laminar flow element, inlet screen, 0.63 inch long standoff,
two ranging washers, 2-1Ú4 inch long 4-40 screw and 4-40 nut.
Range changes in the honeycomb element are made with various
diameter ranging washers. To access the components:
.
1. Remove the unit from the system.
2. Access the LFE by unscrewing the four 10-32 socket head cap
screws from the inlet side of the flow body and remove the inlet end cap. (Note the position of the screws, one has a shorter
length.)
3. Remove the LFE assembly taking care not to bend the inlet
screen. Inspect the sealing O-ring and replace if necessary. Inspect the inlet screen and replace if corroded or damaged. Light
to medium particulate contamination can be cleaned by back
washing with a suitable solvent. Air dry thoroughly.
4-6 IM-82
Page 29
Series 820 Instruction Manual Chapter 4 Maintenance and Repair
4. Inspect the honeycomb element for damage and replace if necessary. Replacement of the LFE or inlet screen requires transducer re-calibration.
5. Re-assemble components. When the transducer is installed in
the system, leak test the connection.
6. To be within the original accuracy, calibrate the transducer (see
page 4-9).
Figure 4-6. High Flow Transducer LFE Cleaning
Caution!
the LFE from the
meter will change
your calibra- tion.
the LFE unless you are
prepared to re-calibrate
Removing
Do not remove
the instrument
.
High Flow Transducers:
The high flow LFE is similar to the honeycomb element used in the
medium flow body but larger in diameter. The high flow body consists of four parts: inlet tube, inlet cap, main flow body and end cap.
The inlet tube is only removed to inspect and replace the sealing Oring between the inlet tube and inlet cap. To access the components:
1. Remove the unit from the system.
2. To remove the inlet screen, remove the four 1∕4-28 socket head
cap screws on the inlet side of the flow body and separate the
inlet cap from the main flow body.
3. Inspect the inlet screen for damage and corrosion and replace if
necessary. Light to medium particulate contamination can be
cleaned by back washing with a suitable solvent. Air dry thoroughly.
4. Inspect the sealing O-ring for damage and replace if necessary.
The inlet screen is mounted with the fine mesh side facing the inlet.
IM-82 4-
5. To remove the LFE loosen and remove the four threaded rods
holding the end cap to the main flow body. Separate the end cap
from the main flow body and remove the LFE assembly. The LFE
7
Page 30
Chapter 4 Maintenance and Repair Series 820 Instruction Manual
assembly consists of: 6-32 x 31∕8 inch long screw, a #6 washer,
two ranging washers, honeycomb laminar flow element, LFE,
spacer, inlet filter, and 6-32 nut.
6. Inspect the honeycomb element for damage and replace if necessary. Replacement of the LFE or inlet screen requires transducer re-calibration.
7. Re-assemble components. When the transducer is installed in
the system, leak test the connection.
8. To be within the original accuracy, calibrate the transducer (see
page 4-9).
Caution!
corrosive gases, purge the un it
thoroughly with inert dry gas
before disconnecting from the
gas line.
When using toxic or
Sensor Cleaning and Inspection
Due to sensor design variations, the following sensor cleaning in-
structions are for Model 822-S/824-S
models must be returned to the factory.
Sensor cleaning is accomplished by simply rodding out the sensor with the Sensor Cleaning Stylette, part number “CKÓ available from Sierra. A 0.028 inch diameter piano wire may also be
used.
To access the sensor for inspection or cleaning:
1. Remove the transducer from the system. Remove the two socket head access port plugs with a 1Ú4-inch Allen wrench. Visually inspect the sensing ports and sensor.
1. Use a hemostat or tweezers to
push the cleaning wire into the
downstream opening of the
sensor tube. Do not force the
cleaning wire, move it back and
forth–DO NOT TWIST OR
ROTATE.
only
. All other transducer
2. Flush the sensor tube with a
4-8 IM-82-E
non-residuous solvent compatible with the O-ring material. In
cases where solids are deposited in sensor, units should be
returned to factory for complete cleaning and re-calibration.
Page 31
Series 820 Instruction Manual Chapter 4 Maintenance and Repair
3. Blow dry all parts with dry nitrogen and re-assemble. When the
transducer is installed in the system, leak test the connection.
Re-zero the transducer (see Chapter 3).
Transducer Calibration
Calibration of Sierra’s flow meters requires a calibration standard
of at least four times the accuracy of the transducer. Sierra’s Cal-
Caution!
It is important that this
transducer be calibrated
only by qualified personnel.
Bench Automated Primary Calibration System is the preferred method of calibration and is used at the factory for all calibrations
from 10 sccm up to 50 slpm. Most calibrations can be performed
with a digital voltmeter (DVM) or multimeter with 0.25% accuracy
and four digits, dry nitrogen and the K-factor tables included in this
manual. Flow meters require a metering valve for setting a constant
flow rate.
The following procedures are offered as guidelines for calibration.
It is always best to return the transducer to the factory for calibration. Calibration checks and minor adjustments to the zero and full
scale are made via the access ports in the enclosure. If the linearity
needs adjustment (when installing a different bypass to change the
range) skip Step 2 and Step 3. If linearity does not need adjustment, complete only Steps 1 through 3.
Step 1. Warm Up
Plug in the unit to be calibrated and allow at least 30 minutes warm
up time before attempting any adjustments.
Step 2. Zero Adjust
Slide open the zero and span access doors. Connect a DVM or
multimeter to the transducer output pins. Adjust the zero potentiometer for 0.0 volts (4 mA) at zero flow.
Step 3. Check Full Scale
Generate full scale flow using a metering valve in-line with the unit
under test. Compare the indicated flow rate with the flow standard
reading. If they agree to within ±10%, adjust the span potentiometer for exact agreement. If the readings do not agree within ±10%, attempt to determine the cause of disagreement. Possibilities are:
leaks in the system or in the transducer
wrong or improper use of K-factor
wrong or improper correction for temperature and pressure
partially clogged or dirty sensor tube
IM-82 4-
9
Page 32
Chapter 4 Maintenance and Repair Series 820 Instruction Manual
• replacement of components in the flow path do not exactly
match the original parts
This completes transducer calibration. To adjust linearity, continue
with Step 4.
Step 4. Adjusting Linearity (see Figure 4-7)
First gain access to the printed circuit board inside the enclosure:
1. For units with the digital display, carefully rotate the display
until it hits the top plate. Slide the display’s two side panels up
and remove. Move the display aside taking care not to damage
the connecting cable.
2. Remove the two Phillips head screws from the top of the transducer enclosure. Remove the two Phillips head screws from the
back of the transducer enclosure. Pull the enclosure panels off.
3. Orient the transducer with the component side of the circuit
board facing you. Plug in the transducer and allow to warm up
for at least 30 minutes.
Step 5. Zero Adjust
Connect a DVM to the transducer output pins. Adjust the zero potentiometer for 0.0 volts (4 mA) at zero flow.
Step 6. Calibrate 25%
Use the calibration standard to set a flow rate of 25% of full scale.
Adjust the span potentiometer R21 for 1.25 volts (8 mA) at the
output of the transducer.
Step 7. Calibrate 50%
Increase the flow rate to 50% of full scale. If the output is within
+0.05 V (0.2 mA), no adjustment is necessary. If the output is
beyond these limits, install a jumper block at J1 in the appropriate
position (see Figure 4-7). Adjust R25 for the proper reading.
Step 8. Calibrate 75% and 100%
Set the flow to 75% of full scale. If the output is outside the limits
set in Step 7, install a jumper block in J2 in the appropriate position. Adjust R27 for the correct reading. Repeat this procedure for
100% flow using R29. Repeat Steps 6 through 8 at least one more
time.
4-10 IM-82
Page 33
Series 820 Instruction Manual Chapter 4 Maintenance and Repair
When you suspect that the transducer is not operating correctly,
there are a few simple checks that can be made before taking the
unit out of service:
1. Make certain that there are no leaks in the gas line.
2. Check that all cables are connected and are in good condition.
3. Verify that the power supply is in the correct range and
properly connected to the transducer.
4. Double check connector pin outs when replacing another manufacturer’s transducer.
This information is provided to help locate the cause of a transducer failure. It is not intended to be an all inclusive repair guide. For
most repairs, the unit should be returned to the factory for service.
IM-82 4-
11
Page 34
Chapter 4 Maintenance and Repair Series 820 Instruction Manual
r
Problem
Possible Cause
Solution
No output No power
Inlet filter screen clogged
Clogged sensor
PCB defective
Plug in power supply Clean or
replace screen Return to
factory for cleaning* Return to
factory for repair
Unit will not zero
Gas leak
Application requires high pressure and non-horizontal mounting
PCB defective
Find and correct leaks
Re-zero transducer
(see Chapter 3)
Return to factory for repair
Reads full scale
with no flow
Gas leak
Liquid present in system
Defective sensor
Find and correct leaks
Check for liquid in flow path
Return to factory for repai
Output too highIncorrect calibration or K-factor
Liquid present in system
Defective sensor
Correct calibration/k-factor
Check for liquid in flow path
Return to factory for repair
Out of calibrationDirty or clogged sensor
Change in composition of gas
Gas leak LFE dirty Inlet
filter screen clogged
Incorrect inlet conditions
(1/2-inch size models)
PCB defective
*Model 822-S/824-S see sensor cleaning instructions
Return to factory for cleaning*
See K-factory tables
Find and correct leaks
Clean LFE
Clean or replace screen Replumb transducer correctly
(See Chapter 2)
Return to factory for repair
4-12 IM-82
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Series 820 Instruction Manual Chapter 4 Maintenance and Repair
Returning Equipment to the Factory
Factory Calibration—All Models
Sierra Instruments maintains a fully-equipped calibration laboratory. All
measuring and test equipment used in the calibration of Sierra transducers
are traceable to NIST Standards. Sierra is ISO-9001 registered and conforms to the requirements of ANSI/NCSL-Z540 and ISO/IEC Guide 25.
Instructions for Returning Your Instrument for Service
The following information will help you return your instrument to Sierra
Instruments' Factory Service Center and will ensure that your order is
processed promptly. Prices may vary depending on the flow range, type of
gas and operating pressure of your unit. To request a rough estimate of the
pricing, contact your local Sierra Instruments distributor or contact one of
our offices directly. A detailed quote will be provided following a full
evaluation of your instrument.
Please follow these easy steps to return your instrument for factory service:
Caution!
Always fully neutralize any
toxic gas trapped in- side
the instrument before
removing it from the gas
line.
1. Obtain a Return Materials Authorization (RMA) number from the
Sierra Instruments website at
http://www.sierrainstruments.com/rma/login.php
2. If you require service beyond calibration, but do not know which
service(s) will be required, describe the symptoms as accurately as
possible on the RMA form.
.
3. Pack your instrument carefully. Use the original packaging and
foam or bubble wrap (packing peanuts NOT recommended) and
include a copy of the RMA form (complete with Sierra supplied
RMA number) with the unit(s).
4. Ship the unit(s) to the following address:
Sierra Instruments, Inc.
Attention: Factory Service Center
5 Harris Court, Building L
Monterey, CA 93940 USA
IM-82 4-
13
Page 36
Chapter 4 Maintenance and Repair Series 820 Instruction Manual
CUSTOMER SERVICE AND SUPPORT INFORMATION:
Email Technical Support:
Email Sales:
FACTORY USA (Monterey, California)
PHONE: 831-373-0200
FAX: 831-373-4402
EMAIL: service@sierrainstruments.com
European Sales & Service Center (Egmond a/d Hoef, Netherlands)
PHONE: +31 72 5071400
FAX: +31 72 5071401
EMAIL: service@sierra-instruments.nl
Asia Sales & Service Center (Shanghai, Peoples Republic of China)
PHONE:
FAX: +86 21 5879 85861
sales@sierrainstruments.com
TOLL FREE: 800-866-0200
+ 86 21 5879 8521
SAFETY NOTE ABOUT PURGING
service@sierrainstruments.com
WARNING: When toxic or corrosive gases are used,
purge unit thoroughly with inert dry gas before disconnecting from the gas line to prevent personnel from being injured when coming in contact with the instrument.
If an instrument used with a toxic or corrosive gas is returned to the factory, a Material Safety Data Sheet
(MSDS) must be enclosed & attached to the outside of
the box to alert Sierra personnel of the potential hazard.
Also, make sure the inlet & outlet are solidly plugged off.
4-14 IM-82
Page 37
Series 820 Instruction Manual Appendix A
Appendix A Conversion Formulas and Gas Tables
Conversion of Flow Rate to Other T and P Conditions
The flow rate of your transducer is referenced to certain “standard”
conditions of temperature and pressure. Unless otherwise specified
in your order, these standard conditions are 21 °C (70°F) and 760
mm of mercury (1 atmosphere). If you wish to convert to other
“standard” conditions or to find the “actual” conditions in the pipe
where your instrument is installed, use the following relationship:
P
1
T
2
Q2 = Q
P
2
T
1
( )1 = The standard conditions under which your instrument
was calibrated,
2
= The new standard conditions or the actual temperature
( )
and pressure conditions in the pipe,
1
= The gas mass flow rate referenced to the calibrated standard
Q
conditions (sccm or slm),
1
(1)
Q
2
= The gas mass flow rate referenced to the new standard or
actual conditions (sccm or slm—“S” means “standard,”
accm or alm—“A” means “actual”),
2
P = Absolute pressure (kg/cm
or psia), and
T = Absolute temperature (°K or °R) (°K = °C + 273, °R = °F + 460).
Example 1: Changing “Standard” Conditions
If your transducer has a flow rate reading of 10.00 slm and was cali
brated at standard conditions of 70°F (21°C) and 1 atmosphere (14.7
psia), and if you wish to convert this reading to standard conditions of
32°F (0°C) and 1 atmosphere, then you would use Equation (1) as
follows:
14.7 460 + 32
Q2 = _________________ (10.0) = 9.28 slm
14.7 460 + 70
The flow rate referenced to 0°C will be approximately 7% lower than
when referenced to standard conditions of 21 °C.
IM-82 A-1
Page 38
Appendix A Serie s 8 2 0 I nstruct i o n Manua l
A
Example 2: Finding the “Actual” Flow Rate
If the flow rate and calibrated standard conditions are as given in
Example 1 and you wish to find the actual flow rate at 100°F and
30 psig, then you would use Equation (1) as follows:
14.7 460 + 100
Q2 = (10.00) = 3.47 lm
14.7 + 30 460 + 70
Calculating For a Single Gas
The following tables provide K-factors and thermodynamic properties of gases commonly used with mass flow meters and controllers. The purpose of these tables is two-fold:
1. Calibrating an “actual” gas with a reference gas. This is particularly useful if the actual gas is not a common gas or if it is
toxic, flammable, corrosive, etc.
2. Interpreting the reading of a flow meter or flow controller
which has been calibrated with a gas other than the actual gas.
In applying the tables, the following fundamental relationship is used:
Q1/Q2 = K1/K
2
(1)
Where:
Q = The volumetric flow rate of the gas referenced to normal
conditions of 0°C and 760 mm Hg (sccm or slm),
K = The K-factor defined in equation (6),
( ) 1 = Refers to the “actual” gas, and
( ) 2 = Refers to the “reference” gas.
The K-factor is derived from the first law of thermodynamics applied to the sensor tube, as described in Chapter 1:
H = µC
2
p
T
(2)
-2 IM-82
Page 39
Series 820 Instruction Manual Appendix A
A
Where:
H
= The constant amount of heat applied to the sensor tube,
µ
= The mass flow rate of the gas (gm/min)
C
p
= The coefficient of specific heat of the gas (Cal/gm);
Cp is given in the Table (at 0°C),
Δ
T
= The temperature difference between the downstream and
upstream coils, and
N
= A correction factor for the molecular structure of the gas
given by the following table:
Number of Atoms in the Gas Molecule N
Monatomic 1.040
Diatomic 1.000
Triatomic 0.941
Polyatomic 0.880
The mass flow rate, µ, can also be written as:
µ = ρQ
Where:
ρ
= The gas mass density at standard conditions (g/l);
en in the tables (at 0°C, 760 mm Hg).
Furthermore, the temperature difference, ΔT, is proportional to the
output voltage, E, of the mass flow meter, or
Δ
T = aE
where:
a
= a constant.
If we combine equations (3) and (4), insert them into equation (2),
and solve for Q, we get
(4)
ρ
is giv-
Q = (bN/ρCp)
(3)
(5)
IM-82
where:
b = H/aE = a constant if the output voltage is constant.
-3
Page 40
Appendix A Serie s 8 2 0 I nstruct i o n Manua l
A
For our purposes, we want the ratio of the flow rate, Q1, for an actual gas to the flow rate of a reference gas, Q2, which will produce
the same output voltage in a particular mass flow meter or controller. We get this by combining equations (1) and (5):
Q1/Q2 = K1/K2 = (N1/
ρ1Cp1)/(N2/
ρ2CP2) (6)
Please note that the constant b cancels out. Equation (6) is the fundamental relationship used in the accompanying tables. For convenience,
the tables give “relative” K-factors, which are the ratios K1/K2, instead
of the K-factors themselves. In the tables, the relative K-factor is
K
actual
/KN2 where the reference gas is the commonly used gas, nitrogen (N2). The remaining columns give Cp and p, enabling you to calculate
directly using Equation (6). In some instances, K1/K
K1/K
2
2
from the tables may be different from that which you calculate directly. The value from the tables is preferred because in many cases it was
obtained by experiment. Sierra calibrates every transducer with primary standards using the actual gas or a molecular equivalent reference
gas. The calibration certificate accompanying the transducer cites the
reference gas used.
Example 1:
A transducer is calibrated for nitrogen (N2), and the flow rate is
1000 sccm for a 5.000 VDC output signal. The flow rate for carbon
dioxide at a 5.000 VDC output is:
Q
CO2/QN2
Q
CO2
= K
CO2
/K N2, or
= (0.74/1.000)1000 = 740 sccm
Example 2:
A transducer is calibrated for hydrogen (H2), and the flow rate is
100 sccm for a 5.000 VDC output signal. The flow rate for nitrous
oxide (N2O) is found as follows:
Q
N2O/QH2
Q
N2O
Note that the K -factors relative to nitrogen must be used in each case.
Example 3:
= K
N2O
/K H2, or
= (0.71/1.01) 100 = 70.3 sccm
We want a transducer to be calibrated for use with dichlorosilane
(SiH2Cl2) at a 100 sccm full scale flow. We wish to use the preferred reference gas Freon-14 (CF4). What flow of CF4 must we
generate to do the calibration?
Q
SiH2CL2 /QCF4
100/Q
Q
CF4
CF4
= 100/0.869 = 115 sccm
= K
= 0.869
SiH2CL2
/K
CF4
-4 IM-82
Page 41
Series 820 Instruction Manual Appendix A
A
Calculating Dual Gas Mixtures
Equation (6) is used for gas mixtures, but we must calculate
for the mixture. The equivalent values of p, Cp, and N for a dual
gas mixture are given as follows:
The equivalent gas density is:
P ml / mT P1 m2/mT P2
Where:
M1m
( )1 = Refers to gas #1, and
( )2 = Refers to gas #2
The equivalent specific heat is:
Cp = F1C
Where:
F
F
m2=
1
m1 Pi/mTP
1
m2P2/mTP
2
Total mass flow rate (g/min).
p1
+ F2Cp2
N/
p
C
p
The equivalent value of N is:
N Ml / mT N1m2/mT N2
The equivalency relationships for p, Cp, and N for mixtures of
more than two gases have a form similar to the dual-gas relationship given above.
IMPORTANT NOTE ABOUT K-FACTORS:
Please note that if you have a transducer calibrated for a gas such
as methane and wish to use the K-factors to measure a gas such as
air, that the inaccuracy of the measurement can range from ±5 to
10%. The use of K-factors is, at best, only a rough approximation
and should not be used in applications that require a better than ±5
to 10% accuracy.
It should also be noted that certain gases, in similar “families,” will
work exceptionally well with K-factors; however, those instances
are only true when similar thermal properties of the gas
are present.