Support, Knowledge base and FAQ's
Common Hazards of gases and vapors in buildings.
Many hazards are not obvious and may build up in confined spaces or travel throughout the building structure, below is an illustration of some of the more common hazards found in typical commercial buildings.
*VOC (Volatile Organic Compounds) Solvents, Cleaning agents, paint fumes & formaldehydes from carpet and furnishings.
**Machine rooms refer to any room containing water/central heating boilers, refrigeration air conditioning & AHU's.
TOXIC GASES - STANDARD RANGE
| Compound | Symbol | Density Air=1 | Operating Range | Standard Range | A1 | A2 |
| Oxygen | O2 | 1.105 | 0~25% Vol. | 0~25% Vol. | 19% | 17% |
| Carbon Monoxide | CO | 0.967 | 0~2000ppm | 0~250ppm | 30ppm | 200ppm |
| Hydrogen Sulphide | H2S | 1.188 | 0~500ppm | 0~50ppm | 5ppm | 10ppm |
| Sulphur Dioxide | SO2 | 2.263 | 0~500ppm | 0~10ppm | 2ppm | 5ppm |
| Nitrogen Oxide | NO | 1.036 | 0~1500ppm | 100ppm | 25ppm | 35ppm |
| Nitrogen Dioxide | NO2 | 2.62 | 0~200ppm | 0~10ppm | 3ppm | 10ppm |
| Chlorine | Cl2 | 2.473 | 0~250ppm | 0~10ppm | 0.5ppm | 1ppm |
| Hydrogen | H2 | 0.069 | 0~2000ppm | 0-2000ppm | 250ppm | 500ppm |
| Hydrogen Cyanide | HCN | 0.94 | 0~100ppm | 25ppm | 5ppm | 10ppm |
| Hydrogen Chloride | HCl | 1.26 | 0~200ppm | 10ppm | 2ppm | 5ppm |
| Ammonia | NH3 | 0.59 | 0~200ppm | 100ppm | 25ppm | 35ppm |
| Ozone | O 3 | 1.66 | 0~5ppm | 2ppm | 0.1ppm | 0.3ppm |
| Ethylene Oxide | C2H4O | 1.49 | 0~100ppm | 25ppm | 5ppm | 10ppm |
| Phosphine | PH3 | 1.184 | 0~20ppm | 1ppm | 0.2ppm | 0.3ppm |
| Carbon Dioxide | CO2 | 0~2% | 0~2% | 0.50% | 1.50% |
FLAMMABLE GASES - STANDARD RANGE
| COMPOUND | Chemical Symbol | Relative Density Air =1 |
Total Operating Range | Standard Range |
A1 | A2 |
| Hydrogen | H 2 | 0.069 | 0~100% LEL | 4% | 20% | 40% |
| Methane | CH 4 | 0.55 | 0~100% LEL | 5% | 20% | 40% |
| Ethane | C 2 H 6 | 1.048 | 0~100% LEL | 3% | 20% | 40% |
| Propane | C 3 H8 | 1.55 | 0~100% LEL | 2% | 20% | 40% |
| Butane | C 4 H 10 | 2.11 | 0~100% LEL | 1.80% | 20% | 40% |
| Pentane | C 5 H 12 | 2.48 | 0~100% LEL | 1.40% | 20% | 40% |
Why choose Vistec
- We specialise in Gas Detection only
- Established since 1986
- Large practical experience
- High professional level of employees and service
- Engineers nationwide allowing fast response
Calibration
As good safety practice, calibration should be carried out routinely, Vistec have in depth knowledge and a strong relationship with many system manufacturer's, allowing us to carry out calibration correctly to the individual manufacturers specification. The need for routine inspection and calibration arises from the fact that all sensor's depending on the technology used will fail sooner or later for the following reasons:- Degredation over time, requires continous calibration
- Environmental poisoning
Many, particularly older systems do not incorperate fail to safe technology, so it is imperative to have your system checked periodically by a Qualified Gas Detection Engineer.
Allowing Vistec to manage your gas detection system will ensure your gas detection remains a sound inclusion in your companies preventative maintenance and safety policies.