Anyone have any experience in this area? A local company has been doing this for years.They recently bought new filling equipment (to deal with manual handling issues) but failed to address the HSE ACOP that states Splash Filling should be eliminated and all measures to reduce static should be employed. The liquid drops from the nozzle approx 8 feet to the tanker bottom. A COMPEX trained employee also noted that the ATEX zone 1 rated rig extends into the Zone 0 rated tanker space by 30cm, the loading tube is made of aluminium. Since installing the equipment ( but not before) they have "risk assessed" their way out of the situation using the conductivity of the liquid as their only defence and commissioned it. The liquid is a solvent based (Xylene) Resin loaded at an elevated temperature of 90 degrees c. During loading solvent fumes can be seen leaving the tanker loading hatch. Operators often sit on the loading gantry during filling but the process is occasionally left unattended. The tanker is earthed but the loading pump does not cut out if the earth is lost. The operation takes place approx 75m from local houses and 50m from the public highway. On the basis that: 1. The HSE ACOP states that Splash filling should be eliminated (But Hasn't) 2. The ATEX rating doesn't seem to match the application. 3. The Likelihood of a incident has been deemed low (by someone with a vested interest in not rocking the boat) but the consequences could be catastrophic. and 4. The only actual safety system in use is rudimentary at best. Should the local population have anything to worry about?

Ok, a bit more. If the houses and road are 75m & 50m away they will be outside of the hazardous area. Typically hazardous areas don't extend more than 10m/20m - usually less if the system is at atmospheric pressure - but it depends on a number of factors - properties of the xylene, ventilation available. I would assume being an outside location the ventilation is good and always available. So the extent of the LEL is likely to be relatively small. Its normal to work out the LEL extent to '1/2 LEL', beyond which ignition isn't usually considered a problem. However, there is always a risk of a local fire on the site where the tankers are being loaded. Is the site confined/congested or open - this will also give an indication of the risk of an explosion - but see above about ventilation. However if all at atmospheric pressure then a pool fire (see below) is probably the most likely fire scenario. What about the site topography? Could you have a running pool fire? Site drainage should capture run off. It would be a concern about the loading being left unattended, if the operation is entirely manual. Overfilling/spilling being a potential problem. Is there an automatic cut off to the pump once the tanker is full? If so is the cut off control system SIL rated? More info required.

Sorry for the double post - don't know why the IOSH site does it!! Mods, please delete this post and one of the double posts, to tidy up the discussion.

I'm afraid I'm going to have to look into this further although I'm not sure how extra much information I can get. As a local resident with a good engineering knowledge and an understanding of risk assessments I'm kind of acting on information from concerned employees and on behalf of concerned residents. Let me get back on this one. many thanks for you input thus far.

There is a serious potential explosion risk here because the Flash Point of xylene is about 27-29 degC, the vapour leaving the tanker has sufficient air for combustion, so any spark outside the tanker will cause an explosion. JohnW

I don't agree completely with what you have said Ian. Explosion can be assisted by good ventilation if it provides sufficient air/oxygen to a fuel and spark in the right vapour concentration. Think of Buncefield - that started with an explosion, and it seems to have been an unconfined vapour cloud explosion, also known as a fuel-air explosion. JohnW

Also the Buncfield vapour cloud was much bigger - so probably some area of the cloud were confined by the surrounding buildings/equipment etc. Before ignition happened. The scenario given here is a much smaller, open area vapour cloud.

Who is arguing? The HSE page you have linked to is but the 'headline overview'. Specific conditions have to be present for a true explosion. In actual facts many fuel 'explosions' are not true 'explosions' but deflagrations. The speed of the shockwave is not high enough to be considered an explosion when compared against true explosives which generate higher over pressures.. The process safety precautions are somewhat different for flash fires than process explosions. It matters - as the major accident hazard scenarios go some way to determining plant layout, explosion venting, structural strength of structures etc to name but a few issues to consider. It isn't only me who thinks a 'flash fire' is the more likely scenario for the situation explained.

Prevents Tanker overfill

Some positive movement on this. The Health and safety chap on site has come down on the side of the concerned employees and told the Engineering Bods that risk assessed it that submerged is what is required to eliminate the static risk. They were relying entirely on flow rate and conductivity (and a person to do their job perfectly every single time) but failed to take into account Solvent flushes and raised product temp. So a step in the right direction toward best practice it seems. Other issues have been raised and it looks like earth/pump interlocks and better ignition source control will follow. looks like they may be dragged into the 21st century after all.

Well done Digger, hoping for a safe completion of the changes to the job. JohnW