Sensing volatile organic gas compounds

September 2005 Sensors & Transducers

Various sensor technologies are currently used for the detection of toxic and combustible gases. The most common ones are solid state, catalytic bead, electrochemical, infrared and photo-ionisation detectors. The characteristics of each sensor type may be summarised as follows:

Electrochemical (EL)

Detects 20-30 toxic gases in ppb to low ppm ranges. Provides good selectivity for some gases, but has a limited lifetime, typically six months to two years. An important application is for those gases (such as ozone) used in the semiconductor industry.

Catalytic bead (CB)

Detects combustible gases in higher concentrations, from 1 000 ppm to %LEL levels. Not prone to interference from low levels of toxic gas. These sensors have relatively short lifetimes (1-2 years) but good selectivity when used for hydrocarbons.

Solid state (SS)

Detects over 150 gases, both toxic and combustible, in ranges from low ppm to %LEL. The technology offers long life, typically in excess of 10 years, with many lasting 20 years or more. They are typically more prone to interference than other sensor types. They are good for general use and recommended for ammonia and hydrogen applications, where interference is not the problem.

Photo-ionisation detector (PID)

Detects most volatile organic compounds (VOCs) in low ppm ranges including benzene, vinyl chloride, phosphene, and hexane, to name a few. PID's UV lamp requires periodic maintenance.

Infra-red (IR)

Detects CO₂ and hydrocarbons. Offers good selectivity and good lifetime (typically three years or more). Ranges for CO₂ available from ppm to 20% by volume, with the lower ranges offering better resolution. Hydrocarbon ranges are available from %LEL up to 100% by volume, depending on the gas.

A range of portable and permanently-mounted instruments using the above sensors is available from PREI Instrumentation. The company can provide the optimum solution for any specific gas detection application.

For more information contact Steve Herbst, PREI Instrumentation, 011 448 2172, [email protected], www.eprei.co.za

Further reading:

Distance sensor for confined spaces
ifm - South Africa Sensors & Transducers
The O6D100 from ifm has been designed as a powerful all-rounder for typical applications in object detection, distance measurement and positioning.

Read more...

---

Optimise sludge treatment and reduce operational costs
Endress+Hauser South Africa Sensors & Transducers
Endress+Hauser’s inline measuring devices, the Proline Teqwave MW 300 and the Proline Teqwave MW 500, determine the total solids content of wastewater directly through microwave transmission.

Read more...

---

Inclination sensors for motion control
ifm - South Africa Sensors & Transducers Motion Control & Drives
The JBC dynamic inclination sensor from ifm offers accurate angle measurement in the most demanding conditions, filtering out motion disturbances such as vibrations, shocks and vehicle dynamics to deliver reliable inclination values via IO-Link or programmable switch outputs.

Read more...

---

Fully integrated standalone thunderstorm warning system
Senseca Sensors & Transducers Analytical Instrumentation & Environmental Monitoring
Senseca South Africa has introduced its BTD-1 fully integrated, standalone thunderstorm warning system, which detects lightning by monitoring the background quasi-electrostatic field. The system can generate alerts before the first lightning strike, with a detection raterange of up to 83 km.

Read more...

---

Technology and education are critical to advancing safety in the mining sector
Sensors & Transducers
As mining operations across Africa continue to evolve in scale, complexity and automation, the role of advanced safety technologies has become increasingly important in protecting people, equipment and productivity.

Read more...

---

Image processing cameras
Vepac Electronics Sensors & Transducers
The intelligent camera series from Vepac is an integrated camera module consisting of a camera and high speed processor. It offers a high-performance image sensing function at the edge device by embedding standard image processing software or the customer’s developed software.

Read more...

---

OMRON launches non-contact safety door switch
Omron Electronics Sensors & Transducers
OMRON has unveiled its latest innovation in non-contact safety door switches, designed to enhance workplace safety and streamline machinery operations.

Read more...

---

Conductivity sensing as a cornerstone of South Africa’s water smart industry
ifm - South Africa Editor's Choice Sensors & Transducers
South Africa’s engineers operate at the intersection of resource constraint and industrial ambition. Few parameters illustrate this balancing act as clearly as water quality. Whether in municipal treatment works, food and beverage plants or mining operations, the ability to measure water quality accurately and continuously has become non-negotiable.

Read more...

---

Futureproofing pharma, one pixel at a time
Omron Electronics Sensors & Transducers
In pharmaceutical manufacturing, there’s no room for error. Omron’s FH-AI and FHV7-AI vision systems introduce AI-powered inspection that adapts to real-world variability, something conventional rule-based vision systems cannot easily achieve.

Read more...

---

Long-range laser distance measuring sensor
Vepac Electronics Sensors & Transducers
The MS-100A is a long-range laser distance measuring sensor with a range of 150 to 1000 mm. This sensor excels in applications requiring extended measurement capabilities, such as quality control and logistics.

Read more...

---