ION Science Industry Blog

The latest industry news, knowledge and opinion.
16 March 2018

H&S Operational Efficiency: Fugitive emissions

 


During normal operations, leaks can occur from pumps, valves, flanges, storage tanks or during loading and unloading. 

According to the US EPA3, valves and connectors account for more than 90% of emissions from leaking equipment and there are hundreds of pieces of equipment as shown in Figure 3.

15 March 2018

H&S Operational Efficiency: Plant turnaround

 

Hazardous chemicals that pose a risk to humans are normally safely transported within the process but obviously during plant turnaround this is no longer the case.  As lines and reaction vessels are opened they pose a significant risk of over-exposure, without appropriate control measures. 

Concentrations can be several hundred (or even thousand) times higher than the occupational exposure limit (OEL)!

13 March 2018

H&S Operational Efficiency: A vital component of overall business strategy

Operational Efficiency

Generally speaking, health and safety has historically been seen as a barrier to productivity, even the butt of the occasional joke. The worst scenario is people continuing to act in an unsafe manner when no one is looking thinking that in cutting corners they are getting the job done more quickly. However, there is now widespread consensus to the contrary that a strong health and safety (H&S) culture is good for business when viewed as an investment, not a cost and as a vital component of overall business strategy. Creating a sustainable business through continuous improvement leading to operational excellence (OpEx) is a major strategic objective.

 

Benzene
15 February 2018

Benzene Health Issues: Leading & Lagging Indicators

 

Leading and lagging indicators

Health surveillance by conducting a urinary test or blood count can of course show evidence of exposure but these are lagging indicators i.e. after exposure has already taken place by which time damage may have been done.

A preferable leading indicator for benzene exposure would be to monitor using a real-time monitoring instrument such as a photoionisation detector.

These can be fixed, portable or personal devices depending on the application or a combination of all three for maximum worker protection.

Benzene
15 February 2018

Benzene Health Issues: Occupational Exposure Limits

 

Occupational Exposure Limits

The table below shows the existing OELs indicated as an 8-hour time TWA and 15-minute STEL (where stated) for selected EU member states and agencies in the USA.

Recognising the specific concerns over benzene, the EU has turned to the European Chemicals agency (ECHA) to “review and evaluate the information already available and assess the most recent scientific information”. 

Benzene
15 February 2018

Benzene Health Issues: Why It Should Be Monitored

 

Hazardous chemicals that pose a risk to human health are present in many raw materials such as oil. Normally these are safely transported and contained within process pipework and reaction vessels during normal plant operation. However, routine plant repair and maintenance (planned turnaround) or a fugitive release, due to faulty anges on valves for example, can potentially expose workers above the legal occupational exposure limit (OEL). 


Benzene
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

Benzene
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.

Benzene
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.