From industrial processes to chemical storage, chemical spill accidents to environmental monitoring and personal safety the need for gas detection is growing and essential. Several technologies are employed to perform this detection including, catalytic and electrochemical sensors, gas chromatography, flame and photo ionization, and ion mobility spectrometry. The photoionization detector, or PID, method offers perhaps the best of all worlds when compared to the other techniques, yielding fast response, low detection levels, ease of use, small size, portability and affordability.
This is why PID is quickly becoming the top choice for emergency response teams, industrial maintenance and public safety.
Some common applications are:
– Leak Detection
– Perimeter Monitoring
– Spill Detection
– Remediation
– Arson Investigation
– Diesel Fuel Threshold Limit Value Monitoring
– Personal Protection Equipment
– Decontamination
– Law Enforcement – Drug Detection
Operation Principle
Photoionization detection uses a specialized UV lamp that emits high energetic photons. The energy level of the photons depends on the gas fill of the lamp and is measured in electron volt (eV).
When the photons are absorbed by the gas atmosphere to be measured they excite the gas molecules causing the loss of an electron, resulting in ionization of the gas. The number of ionized gas molecules, which are measured as current generated from the movement of electrons in the detector, is proportional to the concentration of the ionized compound. This allows a quantitative measurement of concentration.
However photoionisation is not gas selective because all molecules with ionization potentials less than the photon energy of lamp are ionized. The technique is non-destructive so can be used in conjunction with other detectors for extending the analysis.
Heraeus manufactures a range of PID lamps with varying photon energies to enable a degree of compound selection. A recent introduction has been a dedicated 10.0 eV lamp which is particularly useful for measuring benzene, toluene, ethyl benzene and xylene (BTEX compounds).
Application Spotlight
Measurement of Volatile Organic Compounds (VOCs) using portable Photoionization Detectors (PID) enables fast detection with high sensitivity. VOCs comprise numerous chemical compounds such as toluene and isobutylene and are found in many different industries. Exposure limits for these chemicals can be very low, when exposure occurs over a long period of time. Contact to these substances can present a serious health hazard not only in a manufacturing environment but on the streets as they are shipped. For this reason VOC detection is of paramount importance during emergency spill response actions and in industries where worker exposure must be limited.
While many VOCs are also flammable and can be detected with other technologies, such as a catalytic sensor, the levels of concern are typically at the parts-per-million (ppm) or parts-per-billion (ppb) level. For example, toluene has a lower explosive limit (LEL) of 1.2% and a permissible 8-hour exposure of 50 ppm. Exposures to LEL levels are 240 times higher than the shift exposure level (1.2% = 12,000 ppm).
Obviously, a technology capable of higher sensitivity is required to ensure worker or personnel safety. Photoionization detectors (PIDs) rely on specific physical properties of the VOCs, and many common VOCs have ionization potentials lower than 10.6 eV, which is a common energy level for PID UV lamps.
PID sensors, however, have limited specificity. With different lamp energies like 11.7, 10.6, 10.0, and 9.6 eV, some selectivity is afforded in detection. Despite this they will still only indicate that VOCs are present, but not what type. Many instruments with PID sensors have built-in conversion factors; if you know what type of VOC you are measuring, you can obtain a direct ppm reading on your display.
Heraeus Noblelight, a leading manufacturer of specialty light sources, supplies photoionization detector lamps (PID lamps) used in modern portable gas detection units. Using latest electronics and software, PID lamps can be used in durable and easy-to-use mobile gas alarm units delivering reliable detection results.
Design and Production Expertise
Heraeus has extensively tested and selected materials to establish a quality standard in PID manufacture. Heraeus‘ proprietary manufacturing processes ensure unparalleled performance and consistency over the lifetime of the lamps. High purity of the gas spectrum is achieved throughout the life of the lamp by the use of a Heraeus-design internal cleanser.
Heraeus manufactures a wide range of PID lamps to standard and customer specific designs in both RF and DC versions. For hand-held detectors, RF versions provide the best solution due to demands for smaller size and low power drive circuitry, whereas DC operation is the preferred option for laboratory instruments.
Der Edelmetall- und Technologiekonzern Heraeus mit Sitz in Hanau ist ein weltweit tätiges Familienunternehmen mit einer über 160-jährigen Tradition. Unsere Kompetenzfelder umfassen die Bereiche Edelmetalle, Materialien und Technologien, Sensoren, Biomaterialien und Medizinprodukte, Dentalprodukte sowie Quarzglas und Speziallichtquellen. Mit einem Produktumsatz von 4,8 Mrd. EUR und einem Edelmetallhandelsumsatz von 21,3 Mrd. EUR sowie weltweit über 13.300 Mitarbeitern in mehr als 120 Gesellschaften hat Heraeus eine führende Position auf seinen globalen Absatzmärkten.
Heraeus Noblelight GmbH mit Sitz in Hanau, mit Tochtergesellschaften in den USA, Großbritannien, Frankreich, China und Australien, gehört weltweit zu den Markt- und Technologieführern bei der Herstellung von Speziallichtquellen. Heraeus Noblelight wies 2011 einen Jahresumsatz von 103 Millionen EUR auf und beschäftigte weltweit 731 Mitarbeiter. Das Unternehmen entwickelt, fertigt und vertreibt Infrarot- und Ultraviolett-Strahler für Anwendungen in industrieller Produktion, Umweltschutz, Medizin und Kosmetik, Forschung und analytischen Messverfahren.
Heraeus Noblelight GmbH with its headquarters in Hanau and with subsidiaries in the USA, Great Britain, France, China and Australia, is one of the technology- and market-leaders in the production of specialist light sources. In 2011, Heraeus Noblelight had an annual turnover of 103 Million EUR and employed 731 people worldwide. The organization develops, manufactures and markets infrared and ultraviolet emitters for applications in industrial manufacture, environmental protection, medicine and cosmetics, research, development and analytical measurement techniques.
Heraeus, the precious metals and technology group headquartered in Hanau, Germany, is a global, private company with more than 160 years of tradition. Our fields of competence include precious metals, materials, and technologies, sensors, biomaterials, and medical products, as well as dental products, quartz glass, and specialty light sources. With product revenues of EUR4.8 billion and precious metal trading revenues of EUR21.3 billion, as well as more than 13,300 employees in over 120 subsidiaries worldwide, Heraeus holds a leading position in its global markets.
Kontakt:
Heraeus Noblelight Analytics Ltd.
Torsten Jenek
2-4 Nuffield Close
CB4 1SS Cambridge
+44 (1223) 424100
hna-analytics@heraeus.com
http://www.heraeus-noblelight.com
Pressekontakt:
Heraeus Noblelight GmbH
Daniela Hornung
Heraeusstraße 12-14
63450 Hanau
+49 6181 35-3137
daniela.hornung@heraeus.com
http://www.heraeus-noblelight.com