Alarms, Orca's, and Auroras. pt 1

Alarms, orca's, and auroras. I'm pretty sure that's what I promised you last time, and I've been too damn busy with work to have any new fun since then, so let's do it. 

<Another blog post in three parts, because I write too much, too slowly.>

Alarms

Hydrogen is wonderful. It is abundant, as a gas is lighter than air, and it can be isolated by forcing electricity through water.

Hydrogen is terrifying. It is outrageously explosive. It is odourless, colourless, and tasteless. It burns with invisible flames, and embrittles metals. 

I regularly use hydrogen to fill rubber balloons because of the virtues I listed above.
I wear a full flash coat due to the drawbacks.

Personal protective equipment is the least effective method of risk mitigation though, so as well as a flash coat, hood, googles, gloves, and antistatic boots, we use deionised airflow and implement a network of hydrogen sensors and alarms.

As part of my regular maintenance workflow I perform monthly checks that:

• the sensors are detecting hydrogen at calibration level as they should
• the emergency stops are activated correctly if alarm level is reached
• audible alarms and flashing lights are activated if hydrogen is detected.

In early April I performed my first set of hydrogen alarm verification on Macquarie Island, and, alarmingly, the alarms didn't work.

It's a complicated little manoeuvre to pull off, especially when everyone is still new to the station. I go in to the hazardous area, pump 1L/min of 2% hydrogen in air through a sensor, which hits 20% of the lower flammability limit (LFL) of hydrogen. This should trigger the warning level of our gas detector, which activates the emergency stop, buzzers and sirens in our office, and voice alarms in the mess and accommodation block.

If everything is according to plan I then increase the flow rate of calibration gas to 2L/min, reach 40% of the LFL of hydrogen, and the detector goes into "alarm" state - more voice alarms, more sirens, everything gets very exciting.

It's my first time on the island, my first time doing one of these checks in years, and its a safety system intended to prevent me from exploding; I was being pretty meticulous this time around. And eventually it became clear that everything is not hunky dory.

This put me in the uncomfortable position of needing to debug an alarm system that makes a lot of noise in the main living quarters on station, but I can't hear from point of activation. Only way to tick this box is to ask a lot of people to hang out and listen for loud noises, and make a lot of chatter on the radio.

I was able to determine that everything worked fine at 20% of the lower flammability level, but all the voice systems went silent at 40% (Alarm == silence is the opposite of what I want).

This issue sent me on a multi-day adventure, tearing apart rat's nests of black-magic circuitry, potentially hacked at by various techs over the years, looking for... something that didn't look right. I started off assuming that a component had broken, but you know what they say about assumptions...

Skipping a whole lot of electrical best guessing and estimation, I eventually found out that a previous tech had (hopefully) unintentionally tied the power rail of my alarm relays to the "normally closed" pin on the gas detectors 40% alarm relay. Basically means that everything is fine, right up until the alarm goes off, when all the alarms get switched on, but disconnected from power.

This guy here is the gas detector.

And this is the Met alarms. Lots of lights, everyone is very excited.

Welcome to the rat's nest. The two boxes on the right are full of wiring as well. 

... the front panel is wired up too... 

Relays that activate my alarms.

Found the culprit! That red wire shouldn't be there...

Fortunately figuring out what was wrong was by far the hardest part this time, I fixed it by moving that long red wire ("F") down one connection, and everything makes sense again. The alarms are annoying when they should be annoying now, and I should hopefully be that little bit less likely to blow myself up.

I feel like that may have been a particularly boring blog post. Lots of discussion of work things and wires, very little Macquarie Island or Antarctica. In the name of entertainment here are a few snippets of what I actually do with the hydrogen -

This is where I was taught to release weather balloons. 

This is where I really learned how. 

And this is where I'm doing it at the moment :)