Chapter 49

Flour Power: The detectives help a client eliminate risk at their flour mill.

📂 Case overview: A client has experienced a deflagration event at their flour mill, prompting them to call the detectives to assess what happened and prevent it from happening again. Knowing that an explosion could have serious and potentially fatal consequences, the detectives leap into action. Do the detectives decipher what detonated the dust and deter a deflagration disaster? Read on to find out!

The detectives gather for an emergency meeting and are anxious to find out why. Holmes explains that a client experienced a deflagration event at their flour mill. Keen to solve this case as quickly as possible, Shallot Holmes tells the detectives to gather their things and head straight to the flour mill.

On the way, the detectives do a little brainstorming and discuss the combustion risks posed by large volumes of dried flour powder; Eggcule suddenly yelps, startling the other detectives. “What on earth is it, Eggcule?” says Miss Mapple. “Well, I was doing some research and typed ‘flour mill explosion’ into YouTube and have just seen the devastation that a significant explosion can cause. Shallot Holmes reiterates the importance of the case “Our client was very lucky they only experienced a deflagration at their flour mill as an explosion could be very dangerous.” Cornlumbo was reminded of their last case at the Semolina processing facility, where they recommended using equipment with IP ratings to protect from dust ingress . “Perhaps some of the equipment in the mill is not protected against dust ingress; if dust were to get into electronic equipment – that could have caused the ignition that triggered the explosion,” says Cornlumbo. “You’re right, and it is definitely something we should investigate on-site,” says Holmes.

The detectives arrive at the huge flour mill, which is eerily quiet as all the machinery has been shut down until they can work out what caused the deflagration. The client greets the detectives and shows them the mill. Cornlumbo asks if the equipment is IP rated, and the client assures him it is. Cornlumbo, unwilling to give up on his theory, asks what IP rating the equipment had, knowing that if the rating was not high enough, then fine powders could still get in. Cornlumbo was aware that the finer a powder was, the less energy would be required to ignite it. The client tells Cornlumbo that the equipment has the highest protection against dust ingress of 6. Shallot Holmes asks the detectives what else could be a factor. Nancy Beef says, “The concentration range of flour to air could cause an explosion”. “Very good,” says Holmes, who tells the detectives to all search the mill for areas where flour and air could mix in the correct concentrations. As the detectives spread about the mill in search of clues, Holmes goes through all the regulations for the mill that apply to the case.

There are two directives of particular importance to this facility, explains Holmes. And they are ATEX and IECEx. ATEX ratings denote a permissible range of surface temperatures, and IECEx regulations categorize environments into specific zones with a risk of an explosion. Dust-Ex areas are defined with zones 20 (highest risk), 21, and 22 (lowest risk). Ex-certification, just like IP rating, was very important for a flour mill where the risk of an explosion could be high. As Holmes finishes his explanation, the detectives all come back to share what they have found. Miss Mapple says that she thought some debris, dust, or flour could have gathered on unclean equipment, got hot over time, and finally ignited; however, everywhere she looked was spotless. The client assured the detectives that they were aware of the importance of cleaning surfaces regularly in Dust-Ex zones and even how they took precautions with their cleaning equipment to ensure no sparks were created. They avoided sweeping brushes and compressed air except for non-dusty cleaning activities. They even maintained a slight negative pressure on storage vessels and had special arrangements for transporting air when pneumatic conveyor systems were used according to the guidelines of the UK Health and Safety Executive (HSE) government agency.

The detectives begin to lose faith as they can still not figure out what had caused the deflagration; however, Holmes, ever determined to succeed, asks the detectives to think again. What else might increase the likelihood of an explosion? “Moisture content?” said Nancy Beef. Shallot Holmes has an ‘aha’ moment! “How do you detect the moisture content in the pipes?” he asks the client. The client says they have installed moisture probes into their silos to determine moisture. Holmes asks to be taken to the silos to see the equipment. As Holmes expected, the deflagration occurred in one of the pipes where a moisture probe had been installed. There was a hole in the pipe where the probe had been placed. Holmes determined that the probe had become too hot. The surface heated up past the ignition temperature of the flour, giving rise to spontaneous combustion. Holmes checked the probe and found it didn’t have a Dust-Ex certificate. The uncertified probes are immediately removed, and Holmes recommends investing in an ATEX-certified NIR-Online process analyzer for utilization in potentially explosive dust atmospheres to guarantee safety. The NIR sensors – based on NIR technology , will measure the light absorbed, and this information is used to determine the moisture content and other parameters offering a fast and efficient means of determining numerous quality parameters for flour production. NIR-Online process analyzers are available with a Dust-Ex certification for zones 21 and 22, with the option of an additional enclosure that could even measure applications in zone 20, the highest-risk zone. The client is so relieved that he gives the detectives a cash reward for solving the case and eliminating risk from his production facility.