Feb 05

The Sydney Opera House during Vivid Sydney (2013).

When I first started my career as an electrical building services consulting engineer way back in the twentieth century, an older and wiser mechanical engineer gave me the heads up about my career choice. He said, "Building services is a thankless task: people don't care if they're a comfortable temperature, or they can see, or they can go to the toilet - they only care if they can't. If you do your job right, no one will notice; if you do it wrong, everyone will."

As I have posted before, I believe that engineers are enablers; building services engineers particularly so. Like the cinematographer, the choreographer, the anaesthetist and the teacher, our role is to make other people shine.

I am happy to embrace the anonymity of the role and to design (and build) systems that work without the user really needing to think about it. It is for that reason that the following quote sits at the top of our Design procedure:

Good design is obvious. Great design is transparent. 
Joe Sparano, Oxide Design Co.
Jan 17

I recently read in the January 2012 edition of the Engineers Australia magazine a letter which contained the sentence “Scientific truth is not obtained democratically”.

I believe that this statement is a grave misrepresentation of the way science is conducted and the way scientific hypothesis become scientific laws.

Science, like engineering, is carried out by people and as such is intrinsically bound within a social and cultural context. Indeed, even the matters that attract research attention and funding are determined by those factors, just as the engineering projects that get built are.

My issue is not with the primacy of scientific facts; but a collection of facts is not science in the same way that a collection of dates is not history. Those facts must be combined into hypothesis that explain them and ideally suggest new emergent facts to look for.

The facts of the physical science that engineers are most familiar with are demonstrable in repeatable experiments; the facts of sciences such as geology, climatology, cosmology, sociology, anthropology and economics are not so amenable.

The current paradigm in any field of science is determined by the consensus of the scientists working in that field and is inherently democratic. This is not to say that it is unscientific; consensus has been built from a large body of evidence and it would require an equally large body of new and different evidence to change.

General relativity did not replace Newtonian mechanics overnight. There were 50 years of experimental anomalies before the failures in Newtonian physics allowed general relativity to emerge and a further 30 years before it was democratically accepted.


[Published in Engineers Australia February 2012]

Jan 20

A toilet cisternYou use them every day, several times a day in all probability, yet how often do you stop to consider how they work or, more significantly, why they are there?

The photo to the left shows a typical toilet cistern installed (not by us!) in a client's premises. This is a relatively new cistern installed in a very old building; if you look closely you can see the holes in the wall where the older and larger cistern was secured.

From a user's perspective the operation is straightforward; press the button, the toilet flushes and in a little while you can do it again. But ... what is actually going on inside? To find out, let's lift the lid ... literally!

The photo to the right shows the inside of the cistern. We'll go through it one part at a time:

  1. The cistern itself is simply a reservoir to hold the water.
  2. In the centre is the flushing control consisting of two large buttons (white & blue) that activate a half or full flush respectively. They work by lifting the plunger and releasing the water into the flush pipe. Note that the overflow also drops down the flush pipe on newer cisterns (older styles dump it on the floor).
  3. To the right is the filling controls which is a simple float switch that opens when the water drops and closes when the cistern fills up again. The white plug on the left hand side allows the filling controls to be moved over to suit the water pipe.

The components used in a cistern are simple and pretty robust. The most common problem that occurs is the cistern running continuously; this is usually the result of a perished seal in the flushing control but can sometimes be from a maladjusted filling valve that does not cut off before reaching the overflow level.

So that is the how, now to the why. Why do we use cisterns at all?

Myth buster: It isn't to get water pressure. The pressure in a normal water service is typically 5m (50kPa) or more, what you get from a cistern is the height of the flush pipe; about 0.2m (2kPa), so the water pressure in the pipe will easily flush the toilet. So why?

The purpose of a cistern is to provide a physical air break between the water supply, which is usually what we drink, and the sewer, which contains stuff we'd rather not drink. In actual fact a cistern provides 2 air breaks, the break between the pan and the cistern, and the break between the cistern overflow and the filling valve. It is the first one that matters and it is possible and permitted to flush urinals directly from the water main using a device that creates the air break and a solenoid valve and eliminate the cistern entirely.

Now you know!

Nov 03

How much money should you spend on maintenance?

Like any other investment, and maintenance is an investment, you should keep spending on maintenance whenever the returns exceed the costs. Or, when operating with limited resources, as we always are, whenever the returns on this investment are better than the returns on the next best investment. More...

Jul 29

Recently, both of my sons have become fascinated with card tricks and most evenings I get to be amazed and astounded by their prestidigitation. Given that my youngest is only 7 and has the manual dexterity and deceitfulness common to that age (i.e. virtually none) it is usually pretty easy to see how the trick is done. My other son, however, is 13 and depending on how much practice he has put in, it can be more difficult to work it out.

When a magician amazes me, I know she is doing it with knowledge and skill, not with magic. It's a trick - i.e. the magician is doing something that I can't do. For mine, this makes it more amazing than if it really were magic because this is something that the magician has studied and practiced; magic would just be ... well, magic. More...

May 19

As I write, the American President is castigating an oil company over the massive oil leak in the Gulf of Mexico. This is what politicians do because they and the people they represent refuse to accept that life in general and engineering in particular is inherently risky. This appears to be a relatively new social phenomenon. More...

Apr 07

Following on from me recent posts, ABC Radio National's the Philosopher's Zone recently discussed these very issues - you can find the audio here

Mar 29

We are going to play a game.

I have three boxes, 1 contains a great prize –let’s say a 3 course meal in a 5 star restaurant. The other 2 contain something evil – let’s say cold tinned spaghetti.

You get to choose 1 box. Take your time. Got it?

I am going to assume you chose box number 2.

I will now tell you that box number 1 contains spaghetti and give you the opportunity to swap your box number 2 for my box number 3.

The question is: should you a) swap, b) not swap or c) it doesn’t matter? More...

Mar 05

In an earlier post, I alluded to the challenge of navigating probabilities when new information comes to hand.

Consider the following scenario:

There is a horrible disease that does something horrible (I won’t be too specific because it is horrible). Its incidence in the general population is 1 in 100,000 (this is pretty rare; less than 250 cases in Australia). There is a screening test which is 100% effective at detecting the disease but has a 1% false positive (i.e. there is a 1% chance it will say you have the disease when you don’t). You have just been screened and have been given a positive result. Should you put your affairs in order? More...
Mar 03

The classifications of differant kind of water and wastewater in AS/NZS 3500 can be confusing and perplexing so we offer this chart that hopefully clarifies and classifies the various types used.

Oh, to answer the title, you can drink the 'Network Utility Oporator's Supply' or if you don't heve one, 'Rainwater'.

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