LFB did not follow ‘even basic standards’ in firefighting equipment tests, expert says

The flow tests, conducted by the LFB last year, were designed to assess whether Dr Stoianov’s theoretical estimates could be achieved in practice. 

The equipment tested included an aerial lift platform, also known as a turntable ladder, which allows a firefighter to stand in a cage at the top of an extended ladder-like piece of equipment and spray water through a hose from a height. 

It also tested a ground monitor, a device that can hold and point a hose in the direction of a fire, which can be left on the ground without being held by a firefighter. 

The LFB report on the tests, published in November 2021, concluded that “for all of the flow tests undertaken within optimised practical working conditions, the maximum throw of water achieved using equipment available at the time of the Grenfell Tower fire incident, it was not possible to exceed 62.3m in vertical water throw”. 

Andrew Kinnier QC, counsel to the inquiry, said: “Put differently, the LFB concludes that the LFB aerial appliances’ theoretical maximum reach figures were not achievable in practice and that those aerial appliances were not capable of reaching the top of the tower.”

In a supplementary report, Dr Stoianov disagreed with LFB’s test results, as it did not supply the tested monitors – nozzles – with their rated inlet pressure or water flow rate. 

The water flow rate measures the speed at which an amount of water flows through something (eg 2,000 litres per minute), while the inlet pressure is a measure of the force applied to the water.  

“In relation to the performance tests one, two and three A, the LFB did not supply the tested monitors [nozzles] with their rated inlet pressure and/or flow rate.

“Consequently, the vertical reach of projected water jets observed by LFB in those performance tests is lower than the maximum achievable vertical reach of the tested monitors [nozzles],” Dr Stoianov said. 

“Is it right that you do not accept the LFB’s conclusions in relation to the aerial appliances, because the appliances, and I put this in lay terms, weren’t supplied with the correct water pressure and flow rate that would have allowed them to achieve maximum jet height?” Mr Kinnier asked.

Dr Stoianov said that was “correct” and it was “very surprising, given that LFB had my recommendations”. 

On why the correct pressure and flow was not supplied, he said: “My view was that we do a lot of experimental research and [in] experimental research it’s extremely critical to be able to go in a systematic way to validate your measurement equipment, make sure that specific measurement is put in place and, to my view, LFB did not follow even basic standards in performing experimental tests.

“For example, one very simple approach would have been, as I highlighted in my response, to just measure the nozzle inlet pressure at that particular point and that would have given us a lot of confidence in the repeatability and analysis of these tests, and that was not done.”

When questioned, he clarified that the LFB had used the right nozzles, but they didn’t supply the inlet pressure that he specified in his recommendation. This meant that the pressure was significantly lower than it should have been. 

Dr Stoianov added that that was “really puzzling” from his perspective, “whether that was lack of basic knowledge in pipe hydraulics or there were other factors in place”. 

He agreed that the LFB testing did not cause him to change his previous conclusions.

Dr Stoianov was questioned throughout the day on water supply to the LFB on the night of the Grenfell Tower fire. 

He concluded that the water flow rate extracted from the hydrants at Grenfell Tower was lower than it could have been and put this down to four factors. 

The first was the “low flow discharge coefficient” of the used hydrants, which means the efficiency at which they allow fluid to flow through.

Second, a ‘wash out’ hydrant was mistakenly labelled and used as a fire hydrant – the former should only be used by Thames Water for washing away debris after works. 

Third, there was a lack of coordination between the LFB and Thames Water and, fourth, there were pressure losses between the hydrants and pump appliances. 

In the early morning of the fire, the LFB called Thames Water to send water technicians to the site and also asked for increased water pressure. 

Dr Stoianov said in his report that the communication between the LFB and Thames Water “occurred on an ad-hoc basis and, consequently, the communication was qualitative, imprecise and lacked technical rigour”.

“LFB control incident command did not articulate, quantify and communicate their water supply flow rate needs to Thames Water’s network management centre,” he said. 

Dr Stoianov carried out a mathematical assessment as to whether there was an optimum combination of hydrants that could have delivered greater flow rates to the firefighting equipment on the night of the fire. 

The results showed that it was possible to achieve a flow rate of 7,460 litres per minute without changing pressure control settings, providing the LFB used multiple fire hydrants.

They showed it was possible to achieve a flow rate of 12,000 litres per minute by changing the pressure control settings, provided the LFB used multiple fire hydrants.

“To put that into context, the peak flow rate actually delivered on 14 June 2017 was about 4,320 litres per minute,” Mr Kinnier said. 

Dr Stoianov acknowledged several limitations with his research. 

He said the estimated flow figures are for “illustrative purposes only”, to assess whether it would have been possible to achieve them in the conditions. 

He said the assessment relies on the LFB having up-to-date knowledge of the operational status and flow discharge characteristics of fire hydrants based on tests of those hydrants, which did “not appear to have been the case at Grenfell Tower”.

He also said it relied on the use of multiple fire hydrants and Thames Water providing expert engineering guidance and support to the LFB. 

At the start of his evidence, the inquiry heard a statement from Dr Stoianov’s report, which he wanted to emphasise. It said: “None of this analysis is intended nor should it be taken as a personal criticism of the individuals concerned.

“I have no doubt they acted to the best of their ability in extremely difficult circumstances on 14 June 2017.”

The inquiry continues