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Only 2 Witnesses At Grosvenor Inquiry Have Correctly Answered Proposition. “Is The Response Time Of The Methane Sensor To Knock The Power Off At Greater Than 2.5% Faster Than The Lag Time Of The Ignition Of Methane?” Greg Dalliston (Retired ISHR) And Andrew Self Ventilation Consultant

Only 2 witnesses at Grosvenor Inquiry have correctly answered proposition. “Is the response time of the methane sensor to knock the power off at greater than 2.5% faster than the lag time of the ignition of methane?” Greg Dalliston (Retired ISHR) and Andrew Self Ventilation Consultant

As the Grosvenor Inquiry testimony and evidence has unfolded, I have often sat shaking my head at the responses provided about the response time of methane monitors.

None more so than Gavin Taylor (ex Chief Inspector) who was hired by Anglo by solicitors for the Grasstree and Moranbah North Anglo Mines  for the purpose of reviewing  documentation and present a report concerning the methane exceedances amounting to HPIs?

While not every witness has been asked, out of all the witnesses at the Inquiry so far as I am aware, only 2 have answered the proposition correctly.

That firstly being Greg Dalliston (retired Industry Safety and Health Representative the next day, (day 13 21st August 2020),

We then had to wait another 8 witnesses and 7 months for the next person to provide the correct answer, that being Andrew Self

During the procession of a number of the witnesses have been asked similar questions.

These witness include

  1. Current and ex Queensland Chief Inspectors of Coal Mining
  2. Current Mines Inspectors Mining and Electrical
  3. Current Queensland Site Senior Executives
  4. Current Queensland Mine Managers
  5. Current Queensland Ventilation Officers
  6. SIMTARS Consultants and Researchers
  7. Mining Ventilation Consultants
  8. Industry Safety and Health Representatives.

Why are the majority of these highly placed Statutory Officials and Technical Experts getting this wrong?

If I went and asked any group of Mine Deputies (ERZC’s) or Mines Rescue Brigade Members the question about if there was a delay time in methane detectors reading the actual methane levels present;  95% would answer “Yes, there is a delay of 10 seconds”.

I would bet that even a large percentage of Open Cut Examiners would answer correctly

It is up to the Parties and their Legal Representatives to work out whether there is now a general belief in the Grosvenor Inquiry Hearing room, that Methane Detectors instantly measure the concentration of methane and drop power in milliseconds when it is introduced to an atmosphere of greater than 2.5% methane.

If that is so, they then need to ask themselves whether any such wrongly held belief has impacted on how the Inquiry has been conducted, and the questions asked up yo this point.

 

I have collated the relevant statements from the transcript below

Pg 4 of 101 Day 12 Transcript 20th August 2020 Gavin Taylor (ex Chief Inspector)

Something that perhaps hasn’t been made much mention of, but you may be able to comment on it – is there a degree of lag time involved in the sensor recording a reading?
A. With the methanometer?
Q. Yes.
A. Milliseconds.

pg 31 of 101 Day 12 Transcript 20th August 2020

Q. Mr Taylor, at the start of your evidence yesterday, you were asked about your current role as president of the Mine Managers Association of Australia.
You also have held a number of other roles in the coal mining industry, haven’t you?

A. A number, yes.

pg 45 of 101 Day 12 Transcript 20th August 2020

Q. I just wanted that on the record. The last question is in relation to the response time on the methane sensors.
Are you familiar with the term “lag of ignition of methane”?
A. Yes, I am.

Q. I just want to get your understanding, because you quoted figures of methane sensors responding in milliseconds. You even said nanoseconds.

Do you know if the methane sensor knocks the power off at a time interval that is shorter than the lag time of the ignition of methane?

A. Say that again, sorry, Mr Clough.

Q. Is the response time of the sensor to knock the power off faster than the lag time of the ignition of methane?

A. My understanding is in most instances yes.

 

Greg Dalliston Industry Safety and Health Representative (1993 t0 2018)

pg 28 of 155 Transcript Day 13 21st August 2020

Q. There’s just one last point I want to raise with you, and it’s not addressed in your statement, but it arises out of some evidence you heard Gavin Taylor give yesterday.
You’ve seen a transcript of the evidence that he gave, I take it?
A. Yes, I was reading the transcript this morning, plus I watched some yesterday.

Q. In particular, you might recall that he was asked some questions by Mr Clough about the response times of methane sensors, and you might recall that the evidence that he gave was that a methane sensor would have knocked the power off, to use the vernacular, within I think he said milliseconds and then at one stage said nanoseconds. To your knowledge, is that correct?
A. No.

Q. How long does a methane sensor take, in a general sense, to cut the power

A. My understanding is between 2 and 10 seconds. It’s not instantaneous. Even though the legislation says instantaneous, it’s not. By the time it lapses, it’s probably about that.

Like I said, I didn’t finish the ventilation officer’s course, but, from my understanding, that’s about how long they take.

We did a fair bit of research on that when we wrote the legislation and changed the legislation around gas monitors, where we increased the methane level from 1.5 per cent to 2 per cent, because they sit on the machine, so they’re probably quicker than if a person read and then went and did something with a hand-held gas detector. That’s the reason we changed the gas levels when we rewrote the legislation.

But, yes, they’re not instantaneous.

MR HUNTER: They are the only questions I had.

 

Pg 52 of 121  Day 8 2nd Tranche 24th March Andrew Self

Q. This first graph shows the speed at which the methane concentration at the sensor that’s located on the last shield at the tailgate rose?
A. Yes.
Q. And it shows that it was almost instantaneous?
A. Yes.

Q. It stops, though, just under 4.5. Do you think that’s a valid reading?
A. I think it’s calibration that the sensor reached its full-scale deflection. 

 

 

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