(Water & Electricity don’t mix, as you have doubtless heard.
I once worked for a Company that had the main data suite on the top floor of the building. No danger of flooding up there, you might think, until you realised that it was underneath the rooftop tank room. Failing that, all the power, cabling and telecommunications services came up the riser which also doubled as the flue from the boiler house. This is why the disaster recovery business stays in business!
Anyway, I often wondered how we would cope with a data centre flood and today I found out. Reasonably well, fortunately!)
Have you ever noticed a small puddle of water under the car if you have had the air conditioning on? This is condensation of moisture in the atmosphere on the cooling coils of the unit. The same sort of thing happens in large air conditioners too and it can be a bit of a nuisance. If the unit is running too cold, the coils ice up like older fridges used to and lose their efficiency. If it is running correctly, a slow steady stream of water drips will be collected.
Now our large 50kW sensible heat rated units in our Data Centre have a small reservoir tank where the water collects and it is routinely pumped out when it reaches a certain level. One of the units played up last week and it was blamed on the strainer. However, it turned out that the pump was actually not pumping at all, just busy doing nothing, so to speak.
It is surprising how much water a glorified biscuit tin can hold, whenever I transferred it from the tank to the bucket using a mop, the bucket would be much fuller than expected.
To minimise the impact, we reduced the room humidity somewhat so that less condensate would collect and any overflow would simply be evaporated due to the under-floor hurricane blowing over it.
Anyway, several days and many mop-outs later, we now have our replacement collection tank to replace the slightly less fetching washing-up bowl that the security men have been emptying at regular intervals out of hours. Unfortunately, there was a gotcha…
The units can also humidify the air because if the room becomes too dry there is a risk of static electricity sparks from technicians across to the equipment and computers don’t like high voltage sparks very much at all, indeed it proves fatal for them. So, the air conditioner units also have a humidifier unit in the form of a plastic kettle. It is a rather powerful kettle though, with a three phase 9kW element in it (your average domestic kettle is 3kW). It produces steam which is discharged through a sparge pipe on the far side of the cooling coils and into the underfloor plenum. Now kettles need water supplies and plumbing so each unit has a fresh water feed…
When our stalwart air con engineer removed the tank unit he operated the in-line shut off valve in the feed pipe. Unfortunately, though, the pipe was plastic on the feed side using “push-on” connectors and to cut a long story short, he pushed off the push-on connector, upstream of the shut-off valve. He was found in the data centre sopping wet, holding an unanticipated decorative water feature and panicking somewhat because he was running out of mop buckets!
Fortunately, I knew where the stop cock was (because it was my business to know where it was) and at the time of my leaving the late shift was still waiting for the emergency plumber to come and sort it out as the technician couldn’t put the bits togetehr again (well, not without it leaking).
Putting it in context, a half inch bore pipe would take a long time to fill an underfloor area of several hundred square yards to a depth where it would start to cause electrical problems and in that time we could have gone to tools R us and hired a big Hilti drill to drain it into the restaurant area below…
(A water feature, where it is supposed to be, somewhere planned)
