ION Science Industry Blog

The latest industry news, knowledge and opinion.
12 February 2018

Fixed, Portable or Personal Monitoring for Benzene Detection


Fixed, portable or personal monitoring for benzene detection?

 Applications for PIDs include:-

  • fixed systems for area or fenceline monitoring of fugitive emissions
  • portable instruments for con ned space entry checks or leak detection & repair
  • personal instruments, to alert a worker to a concentration above the regulatory OEL

12 February 2018

PID Detection: An Ideal Solution to Monitor Benzene


The photoionisation detector (PID) has proven to be an ideal solution to monitor benzene within the environment. But there are several considerations that must be borne in mind when choosing an instrument.

PID theory of operation

Figure 1 is a schematic of a typical PID sensor system. A UV lamp generates high- energy photons, which pass through the lamp window and a mesh electrode into the sensor chamber. Sample gas is pumped over the sensor and about 1% of it di uses through a porous membrane lter into the other side of the sensor chamber. The inset on the ‘lower right’ of gure 1 shows what happens on a molecular level. When a photon with enough energy strikes a molecule M, an electron (e-) is ejected. M+ ion travels to the cathode and the electron travels to the anode, resulting in a current proportional to the gas concentration. The electrical current is ampli ed and displayed as a ppm (or part per billion (ppb)) concentration. Not all molecules can be ionized, thus, the major components of clean air, i.e., nitrogen, oxygen, carbon dioxide, argon, etc., do not cause a response, but most VOCs do give a response.

Benzene Gas Detection
12 February 2018

The Effects of Humidity During Gas Detection


Effects of humidity

The presence of humidity in the sample gas can unfortunately disrupt the measurement leading to inaccurate results. Heated inlets to achieve a stable temperature (typically 50oC) are power hungry and a challenge to achieve in, say a refinery, where stringent intrinsic safety (IS) requirements have to be met.

However, looking at Figure 1, the presence of an additional fence electrode within a PID sensor, can overcome the problem and practically eliminate the effect of humidity. It does this by behaving as a conductive break when there is excess current ow caused by the presence of humidity.

12 February 2018

The importance of monitoring benzene


Why is monitoring benzene important?

Unlike other health and safety hazards, the only way to carry out a risk assessment for benzene exposure is to monitor quantitatively. Like other volatile organic compounds (VOCs), benzene evaporates easily and most people can just detect its distinctive ‘aromatic’ smell at concentration between 2.5 and 5 parts per million (ppm) in air but regulatory occupational exposure limits (OEL) are typically 1 ppm. However the ‘direction of travel’ for the OEL is towards 0.1 ppm and knowing that benzene is a hazardous, carcinogenic chemical, it is imperative that the measurement solution is sensitive and accurate.

It must also be capable of operating in harsh process plant environments in the likely presence of dirt, dust, high humidity and interference from other VOC/aromatic compounds.

8 February 2018

What are my workplace benzene exposure limits?


What are your options for measuring benzene exposure within the workplace

Knowing the obligations of legislation and OELs, the question remains, how do I know if my workplace benzene exposures are below the limits for my country? 

Unlike other health and safety issues that are managed by risk assessment, this can only be determined by monitoring.

8 February 2018

Understanding occupational exposure limits for benzene


EU Directive 2017/164/EU5 has introduced indicative occupational exposure limit values (IOELV).

These are health-based, non-binding values, derived from the most recent scientic data available and availability of measurement techniques. For any chemical agent for which an IOELV has been set at EU level, member States are required to establish a national occupational exposure limit (OEL) value. They are required to take into account the EU limit value, determining the nature of the national limit value in accordance with national legislation and current practice. 

8 February 2018

Managing hazardous substances within the workplace


Dangerous substances, in liquid, gas or solid form that pose a risk to workers’ health or safety can be found in nearly all workplaces. According to the European Agency for Health and Safety at Work (EU-OSHA)1, 15% of workers across the European Union (EU) have to handle dangerous substances as part of their job, and another 15% report breathing in smoke, fumes, powder or dust at work which could be hazardous to their health.

Some highly dangerous substances, such as asbestos, are now banned or under strict control. However, other harmful substances are still widely used and consequently legislation is in place to ensure that the risks associated with them are properly managed. The Chemical Agents Directive 2 is ‘celebrating’ its 20th anniversary during 2018. In the UK it is implemented as the Control of Substances Hazardous to Health (COSHH) Regulations 2002 and transposition across the EU has been summarised by EU-OSHA3.

Oil & Gas Benzene MiniPiD
12 January 2018

Using PID for Benzene detection

Rather than having to rely on human senses in a workplace setting it is advisable to use an appropriate form of quantitative monitoring; indeed the onus is on the employer to do the risk assessment.  Remembering the old adage attributed to Lord Kelvin that you can’t manage what you don’t measure, there are methods published by the Health and Safety Executive in the UK and NIOSH in the USA that can be used to capture air samples for later analysis but by definition this occurs after exposure could have taken place. Therefore real-time methods are preferable which can range from fixed, permanent systems for fence line applications, hand-held devices for area measurements or confined space entry and most recently developed, personal monitors that can alert a worker of an immediate hazard.

Oil & Gas Benzene
9 January 2018

The facts about Benzene exposure


Benzene and Benzene exposure 

Today, we look some more at benzene and more importantly benzene exposure. Benzene evaporates easily and most people can detect its distinctive smell at concentrations between 2.5 and 5 parts per million (ppm) in air.

As well as inhalation, benzene can be absorbed into the body through the skin or by swallowing material containing it. The effects on worker’s health depends upon how much benzene they are exposed to and for how long. The immediate effects of a single exposure to a high concentration (hundreds of ppm) include headache, tiredness, nausea, dizziness, and even unconsciousness, if the exposure is very high (thousands of ppm) meaning an acute safety incident.

Oil & Gas Benzene
5 January 2018

12 things you should know about Benzene


  1. Benzene is a chemical that is a colourless or light yellow liquid at room temperature. 

  2. Benzene evaporates into the air very quickly. Its vapour is heavier than air and may sink into low-lying areas.

  3. Benzene is the simplest aromatic hydrocarbon and distinguished as the first aromatic hydrocarbons with the nature of its bonding first established in the 19th century.

  4. Benzene is widely used in the United States. It ranks in the top 20 chemicals for production volume.