Every breathing apparatus set carries telemetry: cylinder pressure, air consumption, movement, and whether the wearer is still, because a firefighter who stops moving is a firefighter somebody goes in for. Set 7 sits on the rack, unworn, cylinder full, and at about three most mornings it logs a wearer breathing hard, moving, then still, and in the morning the cylinder is a third down.
I am the watch manager, and the breathing apparatus is checked at the start of every shift by the people who will wear it.
How the telemetry works.
Each set has a unit on the harness that reads the cylinder pressure and the flow through the demand valve, and a motion sensor that alarms if the wearer stops moving for a set time. When the set is in use it transmits to the entry control board, and everything is logged: who wore it, when they went in, how fast they used their air, when they came out.
On the rack, switched off, a set logs nothing, because nothing is being breathed.
Set 7 logs a wearer between about three and half past, most mornings.
The set is on the rack in the appliance bay. Nobody is wearing it. The watch is asleep upstairs or out on a call, and when we are out the set is on the rack because the appliance carries its own.
The log shows a wearer breathing at the rate of somebody working hard, for about twenty minutes, then moving less, then still, and the motion alarm sounding, and then nothing.
In the morning the cylinder is down by about a third, which is twenty minutes of hard breathing.
What has been checked.
The set. Serviced, and the telemetry unit swapped with set 4's. Set 4 on the rack in set 7's place logs the wearer. Set 7 in set 4's place does not.
The cylinder. Replaced, and the valve checked, and a full cylinder fitted at the end of the shift with the valve closed. In the morning the valve is closed and the cylinder is a third down, which cannot happen through a closed valve.
The bay. The camera shows the rack, and the set on it, and the set's face mask hanging where it hangs, all night, moving only when the air handling comes on.
The log. The telemetry firm has read it, and their engineer wrote that the trace is consistent with a wearer under exertion followed by a period of immobility and that the motion alarm functioned as designed.
The trace.
I have looked at a great many traces, because I read them after every job as part of the debrief. The shape of this one is a shape I know.
It is the shape of a wearer who has gone in, worked, lost their way, breathed hard looking for the way out, and stopped. It is the trace you never want to see on the board, and I have seen it on a board once, in 1998, on a job that is on the plaque by the door.
The set on the rack in the bay is set 7. The set on the plaque job was set 7. It is not the same set. We have replaced every set on the station three times since. It is the same number, on the same peg.
What is done about it.
Set 7 is checked at the start of every shift like every other set, and it passes, and it is worn on jobs and it has never failed a wearer.
The cylinder is refilled from the compressor in the morning, and the compressor's log shows the fill, and the station's air consumption is up by a cylinder a night, which the brigade's audit has queried and which I have answered as training use.
What I do.
I manage the watch.
The one thing I have changed is the peg.
Set 7 hangs on peg 7 and I have moved it to peg 12, at the end of the rack, and left peg 7 empty.
The log still shows the wearer, on set 7, on peg 12, at three, and the cylinder still goes down. But the motion alarm, which used to sound in the empty bay at half past three, loud enough to wake the watch on the nights it happened, does not sound any more.
It stopped the first night after I moved the peg, and I do not know why, except that peg 7 is where the set was hanging on the morning we came back from the plaque job, and where the man who had worn it would have hung it, and did not.