Photochemistry Monitoring system (PCM)

Gasmet PCM is a complete system designed to monitor photochemical reactions by FTIR measurement of the concentrations of gaseous reaction products.

Initially developed to study photoactivity of Titanium Oxide (TiO2) surfaces, the PCM is a versatile research tool for studying various photochemical and surface catalyzed reactions with gaseous reactants and products. The flexible design allows several types of surface specimens and light sources in UV and VIS regions to be used and the gas generator is suitable for both inorganic gases and volatile organic compounds. Typical materials tested with the PCM include self-cleaning cement surfaces, odour-free paints, and photocatalytic air purification materials.

The system consists of a photoreactor, gas generator, sampling system for extracting reaction products, CX4000 FTIR gas analyzer and industrial computer. The photoreactor is a flow-through metal vessel with gas inlet and outlet, a quartz window, UV source, and a specimen holder for the catalytic material which is irradiated with UV light. The gas generator mixes carrier gas and liquid in a heated vaporization chamber and feeds the mixture into the photoreactor. The sampling system provides a sample of the gases after the reactor to the gas analyzer.

The CX4000 gas analyzer used in the Gasmet PCM incorporates a Fourier transform infrared spectrometer, a temperature controlled sample cell, and signal processing electronics. The analyzer is fully equipped for fixed installations and it offers versatility and high performance for all industrial users.

The Gasmet CX4000 is designed for continuous monitoring of gas concentrations in the process and emission gases. It is an ideal tool for analyzing trace concentrations of pollutants in wet, corrosive gas mixtures. The sample cell can be heated up to 180 °C. Sample cell absorption path length is selected according to the application.
The Gasmet CX4000 allows simple calibration using only single component calibration gases. The user can easily configure the analyzer for a new set of compounds.

 

 

 

Technical Data

 

Photochemistry monitoring system (PCM)

General parameters
Measuring principle: Fourier transform infrared, FTIR
Performance: Simultaneous analysis of up to 50 gas compounds
Response time, T90: Typically < 120 s, depending on the gas flow and measurement time
Operating temperature: 5 - 30°C non-condensing, air conditiong recommended
Storage temperature: -20 - 60°C, non-condensing
Power supply: 100-115 or 230 V / 50 -60 Hz
Power consumption: Average 150 W, maximum 300 W

 

Measuring parameters
Zero point calibration: Calibration with nitrogen every 24 hours
(5.0 or higher N2 recommended).
Zero point drift: < 2 % of measuring range per zero point calibration interval.
Sensitivity drift: none
Linearity deviation: < 2 % of measuring range
Temperature drifts: < 2 % of measuring range per 10 K temperature change
Pressure influence: 1 % change of measuring value for 1 % sample pressure change. Ambient pressure changes measured and compensated.

 

Gas generator
Operation principle : Volatile liquid dosing and evaporation
Carrier gas: Synthetic air, nitrogen, calibration gas mixtures (non-aggressive)
Dilution gas flow control: MFC 0 – 5 l/min
Liquid flow, minimum: 1.5 picolitres/min (0.5 µl syringe)
Liquid flow, maximum: 200 millilitres/min (200 ml syringe)
Evaporation temperature: 0 - 200 °C

 

Photoactivation reactor and light source
Reactor material: SS316 stainless steel
Reactor dimensions Diameter 114 mm, height 150 mm, volume approx. 1.5 liters
Optical window: Quartz (UV quality)
Specimen holder Removable, 100 mm diameter disk
Temperature control Reactor heater and temperature controller optionally available
Light source: Various kinds of user suppled light sources can be used:
- Solar emission profile
- Visible light (no UV)
- Ultraviolet only
- LED

 

Sample pump
Operation principle: Metal bellows pump
Wetted parts material: SS316L steel, no polymer tubing used to minimize CO2 and H2O diffusion
Pump flow rate: max. 5 l/min
Flow path: User selectable: flow-through or closed loop

 

Industrial computer (optional)
See Gasmet Industrial Computer Technical Data Sheet

 

Signals (optional)
Analog output: • Output range: 4 - 20 mA, isolated
• Channels: 16 freely programmable
Analog input: • Input range: 4 - 20 mA, isolated
• Channels: 8 freely programmable
Digital output: • Output range: 24 VDC
• Channels: 16 freely programmable
• System alarm, Service Request, Maintenance, Concentration alarm, Results valid.
Digital input: • Control: By potential free contacts
• Channels: 16 freely programmable
The optional input and output signals can be extended up to 255 terminals of the following types:
  • 4-20 mA output (4 or 8 channels / terminal)
• 4-20 mA or 0-10 V input (1,4,8 channels / terminal)
• 24 VDC digital output (8 channels / terminal)
• relay output (4 channels / terminal)
• digital input (dry contacts, 8 channels / terminal)

 

Interfaces (optional)
Various fieldbus communications for measurement data and status/alarm output and control input:
Supported interfaces:  ModBus, ModBus TCP/IP, Profibus, ASCII, DDE link. RS232 or RS422/485

 

Flow diagram:

 

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