Envent 331S User manual

Envent Engineering Ltd.
Hydrogen Sulfide Analyzer
Model 330S & 331S
Model 330SDS & 331SDS
U SER ' S M ANUAL
Revision 2.4
Jan 2019

Table of Contents
INTRODUCTION ................................................................................................................................................................... 1
Contacting Envent Engineering Ltd ......................................................................................................................................... 1
• Canada Office: (Main) ........................................................................................................................................... 1
• USA Office: ............................................................................................................................................................ 1
• China Office: ......................................................................................................................................................... 2
Warranty & Lia ility Statements ............................................................................................................................................. 2
Limitation of Warranty ............................................................................................................................................................ 2
Disclaimer ................................................................................................................................................................................ 3
Key Sym ols ............................................................................................................................................................................. 3
Warnings & Cautions ............................................................................................................................................................... 3
• Warning & Cautions for 330S & 331S H
2
S Analyzers ............................................................................................ 4
• Warning & Cautions for 330S Analyzer Only ........................................................................................................ 5
• Warning & Cautions for 331S H
2
S Analyzer Only .................................................................................................. 5
Analyzer Specifications ............................................................................................................................................................ 6
PRINCIPLE OF OPERATION ................................................................................................................................................... 8
Physical Reaction ..................................................................................................................................................................... 8
Analysis Cycles ......................................................................................................................................................................... 9
• Dual Sensor Analysis cycle (SDS): ........................................................................................................................ 11
INSTALLATION ................................................................................................................................................................... 12
Installation Requirements ..................................................................................................................................................... 12
• Electrical Requirements ...................................................................................................................................... 12
• Location for the System ...................................................................................................................................... 12
• Space Requirements ........................................................................................................................................... 13
• Sample Point Selection ....................................................................................................................................... 14
• Sample inlet & sample sweep ............................................................................................................................. 14
• Vent line .............................................................................................................................................................. 14
• Sample Volume & Flow Rate .............................................................................................................................. 15
Installation of Analyzer Components .................................................................................................................................... 16
Analog Outputs ...................................................................................................................................................................... 16
Sample Cham er ................................................................................................................................................................... 18
• Sensor Block ........................................................................................................................................................ 18
• Window & Gasket ............................................................................................................................................... 18
• Aperture Strip ..................................................................................................................................................... 19
• Humidifier Unit ................................................................................................................................................... 19
• Eductor Block ...................................................................................................................................................... 21

Receiving the Analyzer .......................................................................................................................................................... 22
• Unpacking the Analyzer ...................................................................................................................................... 23
• Standard spare parts for 330S H
2
S analyzers: ..................................................................................................... 23
• Standard spare parts for 331S H
2
S analyzers: ..................................................................................................... 24
Installation procedure & Start-up ......................................................................................................................................... 24
OPERATION & CONFIGURATION ........................................................................................................................................ 26
Analyzer Display Interface ..................................................................................................................................................... 26
CALIBRATION PROCEDURES ............................................................................................................................................... 28
H
2
S Gas Cali ration ................................................................................................................................................................ 28
Re-zero Sensor Procedure ..................................................................................................................................................... 29
MAINTENANCE .................................................................................................................................................................. 31
H
2
S Sensing Tape Change Procedure ..................................................................................................................................... 31
Sample Conditioning System Cleaning Procedure ................................................................................................................ 32
• Material List ........................................................................................................................................................ 32
• Procedure ........................................................................................................................................................... 32
TROUBLESHOOTING .......................................................................................................................................................... 34
APPENDICES ...................................................................................................................................................................... 44
Recommended Spare Parts List ............................................................................................................................................. 44
Chico A Sealing Compound: For sealing fittings in Hazardous Locations .............................................................................. 45
Safety Data Sheet for H
2
S Sensing Tape ................................................................................................................................ 46
Risk Assessment - Safety Information ................................................................................................................................... 51

List of Figures
Figure 1. H
2
S Analyzer Principle of Operation Diagram .............................................................................................9
Figure 2. H
2
S Analysis Cycle ..................................................................................................................................... 10
Figure 3. Space Requirements for the 330S & 331S H
2
S Analyzers ......................................................................... 13
Figure 4. 331S Recommended Venting for 331S (Same for 330S model) ............................................................... 15
Figure 5. AO 4-20 mA Output Wiring Options ......................................................................................................... 17
Figure 6. Sample Cham er (Exploded View) ........................................................................................................... 18
Figure 7. Envent's Humidifier Unit for 330S & 331S ................................................................................................ 20
Figure 8. Humidifier Unit Installed in a 331S H
2
S Analyzer ..................................................................................... 21
Figure 9. Eductor Block (Venturi Effect) .................................................................................................................. 22
Figure 10. 330S Display (left) & 331S Display (right) ............................................................................................... 26
Figure 11. 331S & 331SDS Sensing Tape Change .................................................................................................... 31
List of Tables
Ta le 1. 330S/331S H2S Analyzer Specifications ........................................................................................................7
Ta le 2. Sample Volume and & Flow Rate .............................................................................................................. 15
Ta le 3. Aperture Strips & Ranges ........................................................................................................................... 19
Ta le 4. Display Button Description/Function ........................................................................................................ 26
Ta le 5. Display LED Description/Function .............................................................................................................. 27
Ta le 6. Hydrogen Sulfide Properties ...................................................................................................................... 51
Ta le 7. Hydrogen Sulfide Quantities & Health Effects ........................................................................................... 51

Envent Engineering Ltd. Page 1 Revision 2.4
INTRODUCTION
This manual provides all the necessary information to install, operate and maintain the
330S, 330SDS, 331S and 331SDS model H
2
S Analyzer units. This manual is
intended for all technical level users.
Throughout this document will be referring to the models 330S and 331S. However,
the information applies equally to the 330SDS and 3301SDS (Dual sensor), unless
otherwise stated. To clarify, the difference between an "S" model and a "SDS" model
analyzer is the second sensor the "SDS" has to measure H
2
S giving it the capability to
measure H
2
S from two different samples at the same time; the DS stands for Dual
Sensor.
The Envent 330S/331S H
2
S Analyzer is a uniquely rugged and simple design that
utilizes lead acetate based detection which provides a linear and interference-free
output of H
2
S concentration. This analyzer can measure a wide range of hydrogen
sulfide concentrations from parts per billion (ppb) concentrations to parts per million
(ppm) concentrations. With the addition of a dilution sample system, it can read high
concentrations in percentage up to 100%. There are other options available such as
the sample system for H
2
S analysis in liquids or the addition of a hydrogen reaction
furnace for total sulfur measurements.
Contacting Envent Engineering Ltd
This manual covers most of the important information the user is going to need to
install, operate and maintain the 330S/331S H
2
S Analyzers. If more information is
required, you can contact us at:
Canada Office: (Main)
Toll Free: 1 (877) 936 - 8368
Tel: (403) 253 - 4012
Fax: (403) 253 - 4016
Email: [email protected]
Hours of operation: Monday to Friday – From 8:00 am to 4:30 pm (Mountain Time
Zone). Offices closed on statutory holidays.
USA Office:
Tel: [phone] - 4421

Envent Engineering Ltd. Page 2 Revision 2.4
China Office:
Tel: (86) 138 - 0119 - 1148
For further information on our products and most updated manuals/product catalog
please visit: www.envent-eng.com
Warranty & Liability Statements
Products manufactured and supplied by Envent Engineering Ltd unless otherwise
stated are warranted against defects in materials and workmanship for up to 18
months from the date of shipment or 12 months from date of start-up, whichever
occurs first. During the warranty period the manufacturer will, as its option, either
repair or replace products, which prove to be defective.
The manufacturer or its representative can provide warranty service at the buyer's
facility only upon prior agreement. In all cases the buyer has the option of returning
the product for warranty service to a facility designated by the manufacturer or its
representatives. The buyer shall prepay shipping charges for products returned to a
service facility, and the manufacturer or its representatives shall pay for return of the
products to the buyer. The buyer may also be required to pay round-trip travel
expenses and labour charges at prevailing labour rates if warranty is disqualified for
reasons listed below.
Limitation of Warranty
The foregoing warranty shall not apply to defects arising from:
•Improper or inadequate maintenance by the user;
•Improper or inadequate unpacking or site preparation/installation;
•Unauthorized modification or misuse;
•Operation of the product in unfavorable environments, especially high
temperature and/or high humidity;
•Corrosive or other damaging atmospheres or otherwise outside published
specifications of analyzer.
Envent Engineering Ltd carries no responsibility for damage cause by transportation
or unpacking, unless otherwise specified in the incoterms.
Extended warranty may be available with certified start-up. Contact Envent
Engineering Ltd for details.
Envent Engineering Ltd reserves the right to change the product design and
specifications at any time without prior notice.

Envent Engineering Ltd. Page 3 Revision 2.4
Disclaimer
No other warranty is expressed or implied. The manufacturer specially disclaims the
implied warranties of merchantability and fitness for a particular purpose.
The sole remedy of the buyer shall in no case exceed the purchase price of the
analyzer.
The manufacturer shall not be liable for personal injury or property damage suffered in
servicing the product. The product should not be modified or repaired in a manner at
variance with procedures established by the manufacturer.
Key Symbols
The following symbols are used throughout this manual. They are intended to draw
attention to important information.
Description of hazards that could result in major injury or death.
Description of hazards that could result in minor injury or property damage.
Description of important information regarding safety of personal and/or property.
Caution: hot surface.
Description of useful information to help understand a concept.
Warnings & Cautions
This section covers all warnings and cautions for the 330S and 331S H
2
S analyzers.
They are divided into warnings and cautions applicable to both the 330S and 331S,
only 330S, and only 331S H
2
S analyzers. Please read and understand all statements
as they are for your own safety when installing, operating and maintaining the
analyzer(s). Some of these statements are also noted throughout the manual when
relevant.

Envent Engineering Ltd. Page 4 Revision 2.4
Warning & Cautions for 330S & 331S H
2
S Analyzers
Do not disconnect equipment unless power has been switched off or area is known to
be non-hazardous.
Turn off power before servicing. Ensure breakers are off before connecting or
disconnecting power supply.
Electrostatic Hazard – Backpan and Certification nameplate must be cleaned only
with a damp cloth to prevent static charging hazard.
Hydrogen Sulfide and/or other hazardous gases may be present under normal
operation – proper precaution and protective equipment is advised.
The analyzers input voltage range shown in Certification Nameplate (e.g., 120 –
240VAC) is limited when installing external devices (e.g., Solenoids).
Incorrect configuration of the analyzer may cause incorrect operation. Injury and/or
damage to facilities may occur. Check analyzer's functionality after configuration
changes have been made.
Total Sulfur Furnace reaches a temperature of up to 900 °C internally after 1 hour on.
Do not touch external surface as it can reach up to 150 °C. Allow enclosure 1 hour
after powering down the analyzer to cool down before servicing.
The analyzer should be mounted in an area in which it is not exposed to vibration,
excessive pressure, temperature and/or environmental variations.
Disassembly of the pressure regulator and solenoids in the field is not advised.
Consult Envent Engineering Ltd if the regulator or solenoid appears contaminated.
Before resuming line pressure, be sure that all port connections, sample sweep and
sample conditioning system are securely installed.
All connections must be leaktight to ensure the effectiveness of the analyzer as well
as safety. The user is solely responsible for the product selection, safety and warning
requirements for the application. If the equipment is used in a manner not specified by
Envent Engineering Ltd, the protection provided by the equipment may be impaired.
Do not use solvents, brake cleaners, soaps, detergents or rubbing alcohol to clean up
analyzer or sample system.
This unit requires a disconnect device rated 24 VDC and 5A max. It must be protected
by a circuit breaker rated 24 VDC and 5A max, and it is to be installed in accordance
with local electrical codes.

Envent Engineering Ltd. Page 5 Revision 2.4
This unit requires a disconnect device rated 240 VDC and 5A max. It must be
protected by a circuit breaker rated 240 VDC and 5A max, and it is to be installed in
accordance with local electrical codes.
Envent Engineering H
2
S Sensing Tapes are suitalbe for use, if stored in the original
sealed package, for 10 years fron date of manufacture. Tapes should be stored in a
coll dry location. If the seal on the package has been broken in storage, the H
2
S
Sensing Tape should be discarded.
Warning & Cautions for 330S Analyzer Only
Substitution of components may impair intrinsic safety and suitability for Class I,
Division 1.
Open circuit before removing cover.
Ensure that the analyzer received is suitable for the electrical classification of the
installation site:
•The 330S is designed for Class I, division 1 Groups CD
or Groups BCD (Check Analyzer Nameplate)
The glass window on the XP enclosure must remain installed in order to maintain area
classification.
Seals not poured. Pour seals before energizing the circuit).
Analyzer may utilize an optional CCS, Model 646 Series pressure switch located on
the side of the XP enclosure:
•Dual seal, MWP 500psi
•Annunciation is visible leakage from the pressure adjustment cover (flow from
this cover can indicate the possibility that a failed primary seal condition could
exist in the pressure switch).
Warning & Cautions for 331S H
2
S Analyzer Only
Substitution of components may impair suitability for Class I, Division 2.
The eductor is required with this model in order to maintain electrical safety and
certification in division 2 areas.

Envent Engineering Ltd. Page 6 Revision 2.4
Analyzer Specifications
Analyzer Specification
Measurement
Method
ASTM D4084 - 07: Standard Test Method for Analysis of Hydrogen
Sulfide in Gaseous Fuels (Lead Acetate Reaction Rate Method)
Ambient
Temperature
0-50 °C (standard) consult factory for other requirements, 0 to 90%
humidity (non-condensing)
Power 12-24 VDC @ less than 3W
Or, 100-240 VAC 50/60 Hz, 5W,
(300W when total sulfur option is included)
Fuse Rating: 5 Amps, 250V, Slow blow, Size: 0.201'' Dia x 0.787'',
Package/Case: 5 mm x 20 mm
Battery (for 1d Controller Board only): Lithium 3.6V, Dia 0.571'' & 0.992''
Long
Electrical
Certification
330S-
DS
Class I, Division 1 Groups B C D or CD T3C Tamb 0 °C to +
50 °C
331S-
DS
Class I, Division 2 Groups B C D or CD T3C Tamb 0 °C to +
50 °C
For more information on Hazardous location certification, refer to the
Envent’s Website.
Output Ranges Standard ranges are between 10-100 ppb and 0-100 ppm
Response Time 20 seconds to 90% of step change
Accuracy ±1.5% of full range on channel 1 (for SDS Models, channel 2 has an
accuracy of ± 2.0%).
For dilution (option): ±2.5%
For Total Sulfur (Option): ±2.0%
For PPB (Option): Based on "base noise average"
Display Graphic Liquid Crystal Display; menu is scrolled by internal button or
magnetic wand (330S)
Outputs Two 4-20mA outputs (loop power required), optional 4-20mA powered
output boards are available
Serial Communication:
(1) RS-232 Modbus protocol
(3) RS-485 Modbus protocol (One RS-485 for remote display option)
Ethernet port as an optional feature
4 SPDT relays (120 VAC 5A maximum)
4 solid state solenoid drivers
Optional
Features
Total Sulfur Utilized when all sulfur compounds need to be measured. A Total sulfur
reaction furnace is added which allows the analyzer to measure total
sulfur
Dilution Sample
System
Utilized when the analyzer needs to measure ranges above 100 ppm. A
permeable membrane dilution system
Liquid Sampling Utilized when a liquid sample conditioning system is required to
measure hydrogen sulfide in Liquids

Envent Engineering Ltd. Page 7 Revision 2.4
Parts Per Billion Utilized when analyzer requires to read in parts per billion (<1 ppm)
Low Tape Sensor Utilized when an alarms is required when the H2S sensing tape needs
to be changed
Low Pressure
Switch
Utilized for alarming when sample pressure drops below 10 PSI
AO Powered
Boards
Utilized for loop-powered analog outputs
Expander AO
Board
Utilized when more than two analog outputs are required
Ethernet Port Utilized for TCP/IP communication capabilities
Auto Calibration Utilized to initiate a calibration based on time of day or manually
Table 1. 330S/331S H2S Analyzer Specifications

Envent Engineering Ltd. Page 8 Revision 2.4
PRINCIPLE OF OPERATION
Physical Reaction
Envent's models 330S and 331S H
2
S analyzers use ASTM D4084 – 07: Standard
Test Method for analysis of hydrogen sulfide in gaseous fuels (Lead Acetate reaction
rate method). This method uses lead acetate impregnated paper. Throughout this
document the term lead acetate tape will be written as "H
2
S sensing tape".
The H
2
S sensing tape reacts when in contact with hydrogen sulfide by the compound
relationship shown below. This tape does not react to any other sulfur compounds in
the gas stream. This makes it free from interference when more than one sulfur
compound is present in the sample stream. The H
2
S reaction is visibly evident by a
brown stain directly on the H
2
S sensing tape.
COOHCHPbSCOOCHPbSH
OH
3232
2)(
2
+ →+
The electronics built into the models 330S and 331S have been programmed to
measure the rate of darkening over time which, in turn, gives the hydrogen sulfide
concentration level. When no H
2
S is in contact with the H
2
S sensing tape, the
analyzer sensor reads 1000 mV (+/- 100 mV).
The sensor block has a LED and a photodiode detector. The LED emits a red beam of
light which is reflected off of the H
2
S sensing tape to the photodiode which detects the
light intensity. The darker the H
2
S sensing tape becomes when in contact to H
2
S, the
less light the photodiode detector receives reducing the millivolt value, which in turn,
increases the H
2
S value. The "SDS" models uniquely measures rate of change on
both sides of the H
2
S sensing tape, allowing for simultaneous readings of two
separate samples.

Envent Engineering Ltd. Page 9 Revision 2.4
Figure 1. H
2
S Analyzer Principle of Operation Diagram
Figure 1 above shows a flow and pressure regulated of a filtered sample gas passing
through the humidifier into the sample chamber. An aperture in the sample chamber,
which differs in sizes depending on the application, allows the gas to come in contact
with the H
2
S sensing tape creating a brown stain.
Flow and pressure are the most important variables when measuring H
2
S and must
be kept at a constant state for the analyzer to measure H
2
S properly. Pressure should
be kept at a constant 15 psig. The lowest pressure found to be tolerable for proper
H
2
S measurement is 0.5 psig. Flow must be kept at a constant flow of 2 cm (83.63
cc/min). A change in flow of +/- 1 cm affects the reading by 10% of full range.
Analysis Cycles
The analysis of the color rate of change on the H
2
S sensing tape is measured in
analysis cycles. An analysis Cycle lasts up to a maximum of 720 seconds (12
minutes).
Do not change the Maximum Analysis Time, consult Envent Engineering Ltd.
Analyzers sold prior to Mid-August 2016 are set to have a 360 second analysis cycle.

Envent Engineering Ltd. Page 10 Revision 2.4
Once an analysis cycle is complete, the motor moves the H
2
S sensing tape giving the
sensor block new tape surface area to start the analysis again. In normal operation, if
the analyzer is being exposed to H
2
S within its range, the analysis cycle should last
between 150 to 210 seconds (1.5 to 2.5 min); the cycle lasts 720 seconds if no H
2
S is
present.
Figure 2. H
2
S Analysis Cycle
Figure 2 shows a complete analysis cycle from when the motor has advanced the H
2
S
sensing tape from a previous analysis (1), to the end of the current analysis (4). Once
the H
2
S sensing tape has finished moving and new tape surface area is exposed, the
reflection of light from the LED to the photodiode detector is at its maximum and
results in a voltage output from the sensor block of 1000 mV (+/- 100 mV). This
voltage is captured by the analyzer and it is referred to as the "Zero Voltage". The
zero voltage will vary for each surface area of the H
2
S sensing tape and will represent
the starting point for the H
2
S reading for that cycle.
From stage (2) to (4) the H
2
S value starts increasing as the millivolt value drops from
exposure to H
2
S. This stage is called "RRA Analysis". The RRA stands for Rapid
Response Algorithm and it is the instantaneous H
2
S readings calculated every 67 ms.
As the H
2
S sensing tape darkens, the RRA value starts going up every second.
Although the RRA values are calculated almost instantaneously, they are not as
accurate as the final reading obtained at the "Concentration Calculation" stage (3) to
(4). However, RRA values can be used as a trigger alarms setpoint in case the
application requires a rapid response time (less than the RRA Analysis completion).

Envent Engineering Ltd. Page 11 Revision 2.4
The first part of the RRA Analysis (2) to (3) completes when the mV value drops 100
mV. Once it drops 100 mV, stage (3) to (4) "Concentration Calculation" starts.
On this stage, the H
2
S slope is optimal for calculating the final H
2
S value for that
Cycle. Algorithms are used by the controller board to calculate as accurately as
possible the H
2
S final value. Once the final value is obtained, it will stay at that value
(shown in the display and 4-20 mA analog outputs) until the next cycle has finished
and updates the H
2
S current reading. This stage will always be 1/5 of the amount of
time it takes stage (2) to (3) to complete. Thus, if stage (2) to (3) took 600 seconds,
then stage (3) to (4) will take 120 seconds.
It is important that the analyzer is used for its calibrated H
2
S range. Do not use this
unit for an application that will require readings outside of its calibrated range. This will
cause the H
2
S sensing tape to run out faster and may cause less accurate readings.
The range is determined by the aperture strip in the sample chamber. For more
information analyzer ranges, refer to "Aperture Strip" on page 19.
Dual Sensor Analysis cycle (SDS):
Dual sensor analyzers have two sensors that read H
2
S from two different samples at
the same time, e.g. Sensor 1: 0-20 ppm H
2
S Sensor 2: 0-200 ppm H
2
S. The analysis
cycle process is the same per sensor as explained earlier in this section; however,
some extra algorithms have been implementing to help with the interaction between
the two sensors and their analysis cycles' timing.
Both analysis cycles for each sensor will always start at the same time. When the
motor moves and new H
2
S sensing tape area is exposed, a new analysis cycle has
started for both sensors. However, the analysis cycles from each sensor will finish at
different times. Either sensor 1 or sensor 2 will finish its analysis cycle first.
Regardless of which sensor finishes first, it will wait for the other sensor to complete
its analysis cycle. Once both sensors have completed their analysis cycles, the motor
will move and new H2S sensing tape area is exposed for a new analysis cycle.
It is important to clarify that when the first sensor has finished its analysis cycle, even
when it is waiting for the second sensor to complete its analysis cycle, it immediately
updates any outputs associated with that sensor (Analog output 4-20 mA, alarms,
display H2S value, etc.).

Envent Engineering Ltd. Page 12 Revision 2.4
INSTALLATION
Installation Requirements
Electrical Requirements
The 330S/331S H
2
S analyzer's controller board can either be 110-240VAC or 10-
32VDC. Consult the analyzer nameplate attached to it or factory calibration certificate
for more information.
Controller board ground connection to chassis is represented by the letters “FG” and
ground symbol.
Certification nameplate shows the voltage range at which the controller board can
withstand (e.g., 120 – 240 VAC), however, when using external devices which are
powered by the controller board (e.g., solenoids), that voltage range no longer applies
and only the external device’s voltage rating shall be used; e.g., 120 VAC rated
solenoid, the analyzer shall be powered with only 120 VAC and not 240 VAC.
The power consumption for a VDC analyzer is 3 Watts and for a VAC is 5 Watts. For
the total sulfur option the power consumption 300 Watts.
Location for the System
First to be considered is the electrical area classification the analyzer will be installed
in. Make sure the analyzer meets the requirements for the installation site. The 330S
H
2
S analyzer is suitable for Class I, Division 1 Groups CD (or Groups BCD by
customer request). The 331S H
2
S analyzer is suitable for Class I, Division 2 Groups
ABCD.
When the total sulfur option is used, the 330S is rated for Class I, Division 1 Groups
BCD and the 331S is for Class I, Division 2 Groups BCD.
The 330S/331S H
2
S analyzer should be mounted in an area in which it is not exposed
to vibration, excessive pressure, temperature and/or environmental variations. The
ambient temperature range for the 330S/331S H
2
S analyzers is 0 to 50 Degree
Celsius. If the analyzer is installed in an area where temperatures go out of this range
or it varies abruptly, Envent Engineering Ltd has options such as cabinets or shelters;
consult Envent Engineering Ltd.

Envent Engineering Ltd. Page 13 Revision 2.4
Space Requirements
Figure 3. Space Requirements for the 330S & 331S H
2
S Analyzers

Envent Engineering Ltd. Page 14 Revision 2.4
Make sure to leave at least 1 feet of extra space on the left side of the 330S H
2
S
analyzer. This will allow proper opening of the side door located at the upper blue
chassis where the H
2
S sensing tape is located.
Sample Point Selection
The sample to the 330S/331S H
2
S analyzer must be representative of the process
stream and should be taken from a point as close as possible to the analyzer to avoid
lag times and sample degradation in the tubing. A probe must be installed vertically
on a horizontal section of pipe ensuring that the sample is drawn from the middle third
of the pipeline.
An optional Genie GPR Probe regulator may be used. The function of this probe is to
ensure a clean dry sample to the analyzer and to reduce the pressure of the sample.
The lower pressure will improve the response time of the analyzer. Refer to Figure 4.
It is advisable that the probe not be installed on a vertical pipe.
Sample inlet & sample sweep
1/4 inch 316 stainless steel tubing and fittings are recommended for the sample inlet
and sample sweep tubing. Sample sweep can be connected to a flare line if available.
Refer to Figure 4.
1/8 inch 316 stainless steel tubing can also be used if the response time of the
analyzer is of particular concern.
Vent line
3/8 inch stainless steel tubing and fittings are recommended for the vent line to a
maximum of 6 feet in length. 1/2 inch stainless steel tubing should be used for vent
lines exceeding 6 feet. The tubing should be installed with a slight downward slope
and should be as short as possible. Refer to Figure 4.
The sample vent line must be tubed to atmospheric pressure outside and cannot be
connected to a flare line or header.

Envent Engineering Ltd. Page 15 Revision 2.4
Figure 4. 331S Recommended Venting for 331S (Same for 330S model)
Sample Volume & Flow Rate
The sample should be supplied to the 330S/331S H
2
S analyzer at 10-15 psig and at a
flow of 83.63 cc/min (set flowmeter at 2.0). A bypass sweep is recommended to
reduce sample lag time in the sample line if it is at high pressure or it is longer than 15
feet (The Standard H
2
S conditioning sample system has a bypass sweep). The
standard sample tubing material is 1/4" 316 stainless steel; however, 1/8" stainless
steel tubing can be used if the response time is critical (refer to Table 2).
Tube
Size
(")
Tube
Gauge
ID (") ID (cm) Flow
(SCFH)
Flow
Std.
(cc/min)
Pressure
(PSIA)
Lag
Time per
100' (min)
Lag
Time per
100' (sec)
3/8 20 0.319 0.810 5 2359 800 36.30 2178
3/8 20 0.319 0.810 5 2359 200 9.07 544
3/8 20 0.319 0.810 5 2359 50 2.27 136
1/4 20 0.181 0.459 5 2359 800 11.69 701
1/4 20 0.181 0.459 5 2359 200 2.92 175
1/4 20 0.181 0.459 5 2359 50 0.73 44
1/8 20 0.081 0.205 5 2359 800 2.34 140
1/8 20 0.081 0.205 5 2359 200 0.59 35
1/8 20 0.081 0.205 5 2359 50 0.15 9
Table 2. Sample Volume and & Flow Rate