The other day, the fan man came to our data centre on his annual pilgrimage. The fire suppression system requires the room to be well sealed so that if it is discharged in anger, it has a good chance of suppressing a fire. (If the room leaks live a seive, fresh air will dilute the concentration to a level where the gas is no longer effective).
Now I have seen the paperwork from such tests before and the final outcome is a simple number- a retention time, in minutes, for how long the room will retain the gas at a suitable concentration. (Ten minutes is the figure in our case). I didn’t entirely understand how they worked out the figure and having spent some time with the Engineer concerned, I have to say that I still don’t entirely understand! At the end of the day, it is a case of “Computer says yes/no” where the various volumes and test results are input into a laptop.
The testing gear is unusual- a false door frame is fitted into a doorway and sealed with a tent-like structure. There is a large round hole at the bottom, into which is fitted a calibrated pressure control device (i.e. a fan) via an elasticated collar. There is a small hole for a sensor pipe to measure the outside pressure (outside to the room, not the actual outside). There is also a clear plastic observation window for looking in (or out) whilst testing. A pair of gauges with associated piping are used for taking the readings during the testing (inside the room).
The room doors have to be closed during the testing of course, although it is OK to be inside the room whilst the fans are on. Indeed, the fan man suggested I stay in the room should anyone want a remote pair of hands on any Servers whilst the main doorway was cluttered up with the tent.
The fan man told me that it was perfactly safe to be in the room as the system only generated about twenty Pascals. He may as well have said that it only generated twenty Quinzi-walloons as I had no idea what a Pascal was as a value. (Indeed, I thought it was a structured software programming language).
It turns out that a Pascal (symbol Pa)is the SI unit for pressure measurement and just to put it in context, it equates to:
1 Pa = 1 N/m2 = 10?5 bar = 10.197×10?6 at = 9.8692×10?6 atm =7.5006×10?3 Torr = 145.04×10?6 psi.
(Isn’t Wikipedia wonderful?)
These are pretty small numbers. I recall having a Boss called Alan Newton in the 80′s and he was effectively dissed in a meeting by someone senior saying that a Newton was a small unit of energy. My weatherpixie tells me that the barometric pressure in Leeds is currently 1,013 hPa (HectoPascals, 1hPa equals 100 Pascals) so there you go.
I half expected the man to blow the fans for 10-15 minutes but it turned out that he just needed to blow (and suck) for a couple of minutes as the readings could be used to derive the performance of the room.
I also nipped into town yesterday lunchtime, tipped off by Helen at work of something that would amuse me- a scrolling display board that flipped between a yellow Time4Change nagvert and a promotion for a MacDonalds Hamburger. Disappointingly, the scrolls had been updated and the nagverts had been replaced with some sort of Bradford is great promotion. Never mind, at least I snapped a couple of telephone boxes to show the campaign is still alive, even if not in motion.
By the way, just in case any overseas readers think that UK phone boxes are still red with Georgian style windows, this photo should clarify that this is not the case. Notice the ventilated lower level for rapid dispersal of fluids.
Schools/Governments set what is taught in the school curriculum, so its only a little step further for Government to advertise its mantra.
¿qué?