Systech - Model EC91 - Intrinsically Safe Oxygen Analyzer
Intrinsically safe ATEX-approved EC91 is an unsurpassed oxygen analyzer for all hazardous areas. The EC91 intrinsically safe oxygen analyzer is an online transmitter for ppm and percent oxygen measurements of gas streams in hazardous area installations. It can detect oxygen levels from as low as 1 ppm up to higher percent levels and can be used in most industrial gases and atmospheres. There is no need for routine maintenance of the fuel cell and the instrument can be easily calibrated, using ambient air or standard calibration samples.
The enclosure is manufactured from moulded glass fibre reinforced polyester, a material with high impact resistance. It will not be harmed by oils, common acids and alkalis, making it suitable for harsh environments. It is protected to IP66/Nema 4X. The EC91 transmits a 4-20mA signal which corresponds to the range of the analyser. Up to six ranges can be specified. A safe area digital indicator and alarm is available as an option.
Standard and custom designed sample systems are available on request. Sample gas may be piped directly to the instrument or remote cell assembly (also certified intrinsically safe). Sample pumps and aspirators are also available.
All the electronic circuits are intrinsically safe and have been certified to ATEX. The EC91 is approved for Ex ia IIC T4 Ga.
The sample pressure should be above 0.1 Bar. If not, a pump or aspirator should be fitted. Connection through the analyser is via a 1/8” tube fitting and a flow regulator should be used on the inlet. If required, dust filters or coalescing filters are available.
Standard or specially designed sample systems can also be supplied by Systech Illinois. Electrical installation must be made via appropriate safety barriers mounted in the safe area. A control room indicator and alarms can also be specified as an option.
The self-powered sensor has no moving parts and is integral to the sample chamber. This solves the problem of output changes due to a flow rate change, making the instrument extremely sensitive and quick to respond to changes in oxygen concentration.
The sensor consists of an anode, electrolyte, and air cathode, together with a diffusion limiting capillary. The rate of diffusion is dependent upon the volume concentration of oxygen in the atmosphere or gas stream. At the cathode, oxygen is reduced to hydroxyl ions, which in turn oxidises the metal anode. The following overall reaction takes place:
2Pb + O2 + 2H2O → 2Pb(OH)2
The sensor has a guaranteed operational life of six months. When monitoring low oxygen concentrations, or if the instrument is not in use, the expected lifetime is considerably longer. The sensor module is inexpensive and easy to replace.
Gas analysis instrumentation for use in hazardous areas is commonly flame proof, explosion proof or intrinsically safe.
Flame proof or explosion proof instrumentation is designed to contain any event, in order to protect the close environment. This instrumentation is expensive and work permits are required in order to maintain the equipment and in some cases to calibrate it.
By contrast, intrinsically safe equipment is absolutely safe, by design. There is no risk of an event, since there is not enough energy stored or available in the circuits to cause an event. Work permits are not required.
Oxygen analysers in hazardous area applications demand the best protection. Intrinsically safe instruments certified to ‘ib’ cannot be installed in Zone 0 areas, as the measurement gas must enter the analyser. ATEX certified ‘ia’ analysers, such as the EC91 can only be used in Zone 0 areas to provide adequate safety protection.
- Monitoring inert blanketing gas in oil and petrochemical applications
- Inert gases and Hydrogen
- Oxygen deficiency monitoring
- Gas purity
- Glove boxes
- Gas line monitoring
- Unsurpassed safety protection
- Air calibration facility
- Maintenance-free 5 year life sampling cell
- Certified for Zone 0
- This instrument has a 36 month warranty which covers any faulty workmanship and normal component failure relating to electronic circuit cards
- 6 selectable
- 0-20, 0-200, 0-2000 (ppm) 0-2%, 0-20%, 0-30%
- Other ranges available on request
- Resolution: 0.05% of scale
- ±2% of reading at 20°C
- ±5% of reading over temperature range
- ±2% of reading + 0.4ppm at 20°C
- ±5% of reading + 0.4ppm + 0.15ppm/°C over temperature range
- Response Time: 90% of reading within 20 seconds
- Calibration Range: Ambient (20.9%) or certified gas
- Measuring Cell Type: Electrochemical fuel cell
- Sample inlet pressure: 0.1 to 1 Barg, up to 17 Barg with optional sample system
- Sample flow rate: 30ml/min to 5 ltr/min
- Sample temperature: 0 to 40°C
- Ambient temperature: 0 to 40°C, RH 0-99% non condensing
- Sample connections: 1/8' OD compression fitting
- Unsuitable gases: Corrosives and solvents
- Power supply: 24Vdc via approved barrier mounted in the safe area
- Power consumption: 10W
- Display Type: Digital LCD
- Analogue outputs:
- Current: 4-20mA
- Maximum loop resistance 400 Ohms
Cabinetry and Mounting
- Enclosure: Reinforced polyester
- Installation: Wall mounted
- Dimensions: 200W x 200H x 175D (mm)
- Weight: 3kg
- Ingress protection: IP66, Nema 4X
- Conformity: 2014/34/EU
- Marking: ATEX II 1G EX ia IIC T4 Ga
- Remote probe holder, Control room display, Aspirators, Sample systems, Alarm outputs.
- Local display: Analogue in place of standard digital display
- Remote probes: 1' NPT or BSP