902 H2S Analyzer /
The model 902 H2S Analyzer / Total Sulphur Analyzer from Galvanic Applied Sciences Inc. is designed to measure H2S in gaseous streams. The 902 detection system is based on the lead acetate tape method. With the optional total sulphur furnace, the unit can measure alternate readings between H2S and total sulphur. The 902 is capable of measuring up to eight streams. We feel it is the best H2S Analyzer on the market today.
The 902 is designed for simplicity of operation, with advanced features. Dual 4-20 milliamp outputs are standard. An optional Modbus communications card is available.
Calibration can be automatic* and can be initiated remotely, at the keypad or at timed intervals. The system can be calibrated with a bottled standard containing H2S in N2.
The 902 H2S Analyzer is the most advanced tape analyzer on the market offering
Windows based GUI software for configuration/monitoring
Modem connection option
Modbus communication RS232 and RS432
8 stream capability with dual mode (H2S & Total Sulphur)
Dual range with automatic switchover
Up to 16 analog outputs available with optional serial card
Automatic calibration feature
Automatic reference gas feature
Extended memory for event, maximum, and hourly, daily average archives
*Galvanic Applied Sciences can add a solenoid to automatically calibrate the 902 H2S analyzer at a specified interval.
Solid State photodiode detector and light source
Simplified direct tape drive
Automatic sensor balance
8 stream capability with dual mode (H2S & total Sulphur)
Up to 16 analog outputs available with optional serial card
Simple operation and low maintenance
Applications 902 of the H2S Analyzer / Total Sulfur Analyzer
Gas processing facilities
Pipeline custody transfer
H2S And Total Sulphur Using Lead Acetate
The lead acetate tape method for the detection of hydrogen sulphide (H2S) in gaseous streams is based on the established principle that H2S reacts specifically with lead acetate to form a lead sulphide brown stain. The concentration of H2S is directly proportional to the rate of change of staining on the lead acetate tape. This principle is the basis for a number of ASTM methods. It is by far the most reliable and simple way to measure H2S in process.
H2S + Pb PbS + H2O
The analyzer moves the treated paper tape one section at a time. Depending on the sample concentration, the tape will begin to darken at a rate proportional to the concentration of H2S in the sample stream. The H2S analyzer exposes a fresh section of tape to the sample inside the sample chamber every 3-4 minutes.
Galvanic Applied Sciences Inc. H2S Analyzers / Total Sulfur Analyzers are designed with the following in mind:
Extended tape life
Fast speed of response
Low power consumption
Optional total sulphur measurement
Tape Transport System
The 902 H2S analyzer uses a common tape chassis unit. It is designed to handle up to 350 feet of lead acetate tape. The stepper motor advances the tape on microprocessor command. In the explosion proof models, the motor is located in an explosion proof box, and connected via a shaft through an explosion proof coupler. The shaft is fitted with a universal coupler to reduce alignment related problems. In the general purpose unit, the motor is mounted inside the chassis.
Sample Chamber Assembly
The sample chamber has a removable aperture that can be changed for various gas concentrations. Typically, the higher the gas concentration to be measured, the smaller the aperture. This aperture restricts the amount of H2S reacting on the tape. The photo detector is a silicon photo diode that converts the darkness to an electric signal amplified at the sensor board to a 0 to 250 millivolt signal. This signal is scaled at the microprocessor. The system uses a single light emitting diode (red) as a light source to illuminate the tape.
Calibration of the 902 H2S Analyzer
The system is self zeroing at every tape advance, therefore calibration is only required every 3-4 months. The units can be calibrated manually or automatically with an optional gautocalh solenoid. Four types of calibration procedures are available:
Analyzer zero: potentiometer adjusting of the sensor balance (self adjusting on 902 series) note: the H2S
analyzer reading is zeroed every cycle (3-4 min) since the measurement is based on rate of change.
Manual span calibration: applying a known gas reference to the H2S analyzer and manually adjusting the
Manual calibration with auto gain adjustments: applying a known reference to the analyzer. The
analyzer then calculates the gain factor internally
Auto calibration: a known gas sample is continuously connected to the calibration inlet port and measured on a user programmed time period. The analyzer automatically calibrates to the known sample.
H2S or COS in a N2 background provides the most stable and convenient calibration source. It is normally recommended to calibrate the analyzer at 60]80% of scale or close to the most critical value such as the alarm limit. Disposable and refillable bottles are available from most laboratory gas suppliers.
A Windows based GUI complete with help files is standard with our 902 H2S analyzer. This allows the full use of data manipulation and report generation functions via the modbus port. The package provides easy configuration via laptop and downloading capability, as well as real time monitoring. The system can be accessed via an RS232 modem.
Total Sulphur Option
The addition of a hydrogenation reaction furnace allows a standard Galvanic Applied Sciences Model 902 H2S analyzer to measure total sulphur concentration. The sample is mixed with a hydrogen stream and heated to approximately 900ºC. At this temperature in the presence of hydrogen all sulphur compounds will be converted to H2S. Also, any hydrocarbon heavier than methane will be cracked to form methane.
Examples of the sulphur reaction are:
Permeable Membrane Dilution
A permeation dilution device (PDD) consists of two chambers formed within a cylindrical housing by a permeable membrane. The membrane blocks particulates and mist droplets, while allowing only gas or volatile components to transfer into a clean dry carrier gas or liquid sweeping the opposite side of the membrane. Compounds such as H2S permeate the membrane at a known rate, proportional to concentration over a given area. The size of the membrane can be designed to provide a ratio between the input and output concentration as low as 10:1 and up to 10,000:1. These systems have proven to be very reliable and stable over time with very little temperature dependency.
Flow Diagram of the 902 H2S Analyzer
3V. 3 Way Valve
Range Extension Systems
Our lead acetate tape analyzers are usually limited to a maximum 50 ppm H2S concentration at around 100 cc/min sample flow. Galvanic Applied Sciences offers a permeable membrane dilution system to allow the measurement in the % range. These dilution systems can be mounted at the analyzer or near the sample point to avoid bringing high concentration H2S or other sulphurs near the analyzer.
Galvanic Applied Sciences can supply custom designs and field commissioning for their systems. Complete analyzer shelters, data acquisition, and sample conditioning panels are part of a total solution integration to the user.
Lead Acetate Tape
Our controlled plant environment ensures top quality in our lead acetate tapes. Our automated process and constant quality checks ensure consistent product. All our tapes are cleaned after treatment to minimize problems caused by paper dust. We can customize our tapes up to three hundred and fifty feet. H2S Analyzers run cleaner and smoother with our tape.