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Member postings for Colin Whittaker

Here is a list of all the postings Colin Whittaker has made in our forums. Click on a thread name to jump to the thread.

Thread: Worried
26/09/2019 13:56:20

Primary school I think was Imperial. Secondary school up to 16 was Metric. The sixth form was back in Imperial. Then University in Metric. Then the Oilfield in American Imperial before almost immediately the Oil Company decided to go Metric.

So now I am pretty well ambidextrous.

Pressure testing in kPa still makes me nervous and measuring reservoir volumes in acre feet is just dumb. I can remember my weight in university in stones and pounds but today I know it only in kgs.

And I almost beat the university challenge student to. "What was the price on the Mad Hatter's hat in decimal currency?"


Thread: Surplus subjects learnt at school.
24/07/2019 04:45:25

The theory says that education especially higher education was designed to show conspicuous consumption. To this end it was essential to study something of no monetary use i.e. I'm so rich I can study solely for effect and not to land a job.

Ideal subjects were dead languages, Latin, Greek, etc. Archeology, History, Geology, Geography, and so on. This is the reason that Pure Mathematics and Theoretical Physics were made separate from Applied Mathematics (and Physics) and could thus be included as Oxbridge degree subjects.

Of course, the prime minister excepted, not many of us can afford to study something that is not vocational and so we started to hear how Latin is actually useful because it teaches us how to name plants and describe medical complaints! Geography and History train the brain etc. As an aside, it is strange that while there are apologists for Latin there are none for Greek despite the extensive use of the Greek alphabet in Science and Engineering.

While at University I struggled with the Mathematics in my Engineering course and failed completely at partial differential calculus, I mean who would ever use this stuff? Subsequently I spent years acquiring and interpreting pressure transient data on gas wells in North Sumatra. I'm sure fate just wanted to push my face in things.

But back to school, which subject least useful? Definitely an O'level in Religious Studies (The Synoptic Gospels). I only had 7 subjects at O'level because I had dropped Latin. That meant I was studying Mathematics, Physics, Chemistry, English, French, Technical Drawing and Religious Studies.

The sixth form was a chance to study what I liked and what I found easy. Is there a connection? And my A'level grades spelled the name of a well known Swedish pop group.

In the middle 70's, when Universities were essentially free, nobody seemed to want to study engineering so I waltzed into Imperial College.

Yes I am a little full of myself and you are free, though not obliged, to remind me of the fact.

Cheers, Colin

Thread: Faulty LED
18/07/2019 03:25:18

I'm not sure what a dimmable brake light is but I can supply some information about LED brake lights.

Filament bulbs, when they get hotter, increase their resistance and this reduces the increase in current that comes from an increase in voltage. This is quite useful when the 12V supply of a car can vary from <12V to >15V.

LEDs in contrast have an exponential increase in current with increasing voltage once the threshold voltage is exceeded. Because of this most LED brakelights include a constant current regulator to keep the LED at its maximum safe current no matter how the 12V supply varies.

If you have a variable dimmable voltage supply fighting with a regulated constant current supply there is a good chance that the constant current supply will lose.

LED lights designed to dim with a variable voltage will either have very complicated electronics or very crude and inefficient resistor regulation where ~90% of the power to the LED is dissipated in a resistor.

But I suspect you may just have the wrong pins for the socket (as well as a dimmable problem).

Good Luck. Colin

Thread: Electric Cars
15/07/2019 03:48:52

What standards should we use for a driving AI?

Must it never make a mistake?

How about ten times safer than the average human?

What about 10% safer than the average human?

What about 10% safer than the average 80 year old driver?

I'm not sure I would go for the last option but the penultimate one looks a good enough starting point as the safety level would only rise with time. Instead we seem to be fixated on total safety.


Thread: Quicksilver
06/06/2019 00:50:09

Working out in the Western Desert of Egypt in the late 1980s I was assigned a bunch of downhole oilfield PVT sample tools of uncertain maintenance history. I eventually decided the best thing I could do was to strip them down and clean them ready for whoever came after me.

Significant amounts of mercury were discovered and disposed of (I can't remember how) while using minimal safety equipment (it was during a period of low oil prices and cost saving on everything non essential). I seem to remember my wedding ring turning silvery and turning to the mechanic to borrow his gas torch to drive off the mercury.

Back in the UK on a field break I decided it might be wise to check on how much mercury I'd absorbed (not wanting to end up as a mad hatter) so I went to my local GP.

"I'd like you to check my mercury level."

"What do you mean? Check your blood pressure?"

"No, no. How much mercury is in my body. I've been working with mercury."

"That's a strange request. I don't know the answer but I'm sure the local hospital does. Let's give them a call....... Hm. They don't know either but they'll find out for us and call me back. Come back tomorrow."

The following day.

"Well there's one lab in the UK that does this analysis just outside Birmingham. They need a urine sample. Doesn't that make you feel special to think of your urine travelling across the UK to a special lab?"

The sample was given, the analysis made and the results obtained. On a safe scale of 0 to 13.5 units of something I was already up to 13 units! I therefore vowed to be much more mercury averse in future. Which cause of action seems to have been effective.

Cheers, Colin

Thread: Another Workshop lighting problem
04/06/2019 14:24:24


LED watts seem to be twice as bright as fluorescent watts, at least for normal bulb lights. I think it also holds for tubes.

An alternative cheap and efficient light source is the mini 220V LED flood lights. I've used a series of 10W LED floods for dazzling effect.


Thread: Chernobyl TV Series
28/05/2019 15:44:55

Just released on HBO in the US and available to the rest of us by devious means if you know how.

The story of the Chernobyl Nuclear Reactor Explosion in episodes (now up to 3).

It's a real bastard of a heavy engineering disaster story. Be thankful you never had anything to do with it.

This TV series has moved me. Please, no jokes.


Thread: heat reflecting foil
27/05/2019 15:23:01

Given that radiators are really convectors is there anything for the foil to reflect?

Thread: Childhood diseases
27/05/2019 15:21:13


Very succinctly put. I wish I'd said that.


Thread: An old Shaper found in Phuket Town
21/05/2019 15:03:07

After driving past a machine shop many times each week for several years I had a reason to walk past it and spotted this beasty dragged outside with some token rain protection draped over it.

It's a SCHUGHARDT & SCHUTTE of LONDON machine. After staring and scratching my head for a while I realised it was some kind of shaper on steroids. I eventually identified the clapper and found it was still free to move. The drive uses belts albeit with an electric motor instead of the original overhead shaft. Whereas a conventional shaper drives the cutting arm backwards and forwards this machine looks to have a sliding carriage for the work piece while the cutter slowly traverses sideways.

My son offered to buy the machine for me but a >2m tall machine is too big even for my spacious workshop.

Why is this monster sitting in Phuket town a few hundred metres away from the Central Festival shopping centre? I guess it is a legacy of the old tin mining days.

large shaper 1.jpg

large shaper 2.jpg

large shaper 3.jpg

Thread: Dialect expressions
27/04/2019 02:34:49

To Plasma,

Never heard mufti being used and a quick search reveals that in arabic it refers to a religious authority.

I started work in the Middle East in Oman and rapidly learned that learning Arabic in Oman would be like learning English in Glasgow. At the end of two years I would occasionally translate Omani Arabic into English for Egyptian Engineers who couldn't understand it themselves.

Working in Syria on an American oil rig I was regularly called upon to translate Yorkshire English from Hull for an American Company Man. That was bizarre.

Bint (a woman) is arabic. Chai (tea) is arabic. But I can't think of any other original loan words I encountered.

26/04/2019 02:04:07

Not dialect but arabic ...

mufta angleezy translates as english key and referred to an adjustable wrench

and I was puzzled why the Fylde school yard slang expression klefted (for steal) was being used by the Omani Bedu as klefty in the expression shufty klefty (see it and steal it) when I was being reminded to close my toolbox. I eventually twigged it was another arabic expression brought back by the British Army from North Africa.

Thread: A close shave or why safety glasses are a must
11/04/2019 03:28:12

One of the hairiest jobs I was ever involved in was pipe backoff on a drilling rig.

Some quick background, sometimes the drill bit gets stuck, it won't pull out of the hole and it won't rotate. As time passes the drill pipe up from the bit slowly gets stuck until only an unknown length of pipe is still free to surface. This free pipe is recovered before the stuck pipe gets fished or the hole deviated around the stuck pipe.

By means of stretch measurements and torque measurements the deepest free point is determined and an attempt is made to unscrew a connection as deep as possible in the free section. Right hand torque to 100% of the safe maximum is applied and is worked down by pulling and relaxing the pipe. The connection to be unscrewed is now placed in neutral tension by calculating and lifting the buoyant weight of the pipe down to the target depth.

It now starts to get a little hairy. Left hand torque to a value of 80% of the previous maximum is now carefully wound in. Please think of stored energy here. Perhaps 10 turns of left hand torque are now being applied with the aid of 2m long pipe tongs pulled by meaty chains to a mile or two of pipe 5-1/2" in OD with 0.3" to 0.4" wall thickness. The final step is to lower an explosive charge (primacord and a detonator) down to the connection to be unscrewed. The bang should initiate the required backoff with an explosive release of stored pipe energy.

As a young green field engineer going out to my first backoff job I was advised by my boss to identify the tool pusher (the oldest and most senior man on the rig floor) and make sure I was standing behind him whenever any torque was on the stuck pipe. I found this advice both powerful and effective.

On a subsequent job I witnessed the pipe tongs flying across the rig floor and the belated dives of the rig crew. Fortunately no one was in the wrong place.

Of course we always had full PPE but I never had much confidence in it providing effective protection.

P.S. I've now ordered some safety glasses from China to sit over my progressive lens spectacles.

Edited By Colin Whittaker on 11/04/2019 03:40:01

Thread: Hydraulic test set up
04/03/2019 02:06:55

Looking at the title I was all set to start sharing my experiences testing oil well pressure equipment at 15,000 psi and above ...

Sadly, having ready the above posts, I can't find any excuse.sad


Thread: Low rate automatic house plant watering system
04/03/2019 02:01:36

Ian S C,

In Singapore it's against the law to breed mosquitoes; not here in Phuket. Irrespective of my water features the neighbours will always have inadvertent water traps. So yes we have mosquitoes and when they begin to annoy then I light a mosquito coil. If you burn them inside something like this then it feels more atmospheric. No malaria in Phuket but there is Denque fever, touch wood, I've not been hit yet.


An adjustable see saw! I like it. Getting some hysteresis should be straightforward but I'm not sure how to realise a mechanically triggered valve. Could a crease in a hose close things reliably?

To all, Has anyone got any details on a multistage siphon where a baby siphon helps trigger a medium siphon that finally triggers a big siphon? It's always fun re-inventing the wheel but ...

Cheers, Colin

03/03/2019 09:19:09

Bazyle, auto siphons at low rates is a concern. I just registered at PhysicsForums to have an excuse for posting the following, on low rate autosiphons. But I can well see myself resorting to a tipping trough if I can't get a siphon to work reliably.

02/03/2019 12:59:28

Adrian, So sorry. I posted before seeing your solution. Great minds etc.


02/03/2019 12:57:48

Guys, articulating the problem got grey cells working.

The solution I'm inclining towards is an automatic siphon (think men's urinal down the pub). Once I have a header tank full of water the siphon starts with enough pressure (around 2.5m height) to reach all of the plant pots.

The obvious temptation is to build it all from transparent plastic, but an opaque set up may be less of a time waster; it's 95% full and I'll have to wait while it triggers.

Now will a single stage siphon suffice or do I have to go multiple stages? siphon strip down

We seem to have a surfeit of Bromeliads and they're pretty tough so I'm not planning on any control to the humidity level of the coconut husk growing media.

Thanks all, Colin

02/03/2019 10:03:32

The background. I live in Thailand. My kitchen is open along one side and has a tiled concrete floor that can handle getting wet. I have house plants in pots along the open wall of the kitchen.

I've just installed a reverse osmosis (RO) filter system to provide drinking water at my kitchen sink.These RO filters generate around three times as much water as they filter. This waste water is normally poured down the drain or, I could use it for house plant irrigation. Back of an envelope and bucket collections suggest I'll have around 5 litres per day to play with.

Trouble is the rate is <<1 l/min so adjustable chokes to distribute the flow to three or more pots will be unworkably sensitive.


Water to a header tank that flushes when full?

A cascade system that waters one pot and then triggers the water to the next and the next? How would that work?

Just fill a watering can and manually water the plants? Come on! I'm an engineer.

Thanks, Colin

Edited By Colin Whittaker on 02/03/2019 10:04:37

Thread: Workshop - indoors or outdoors
27/02/2019 02:33:38

Someone mentioned radon gas ...

A comment from a research scientist colleague in Boston, USA.

Radon gas has always been present in a lot of Massachusetts basements but the cancerous effects were swamped by the far bigger risks from smoking. Now that smoking is much reduced it is becoming possible to detect the epidemiological cancerous effects of radon gas.

And at an even greater tangent, chemical engineers have the worst life expectancy of all professional engineers, so keep those workshop solvent containers well sealed.

Edited By Colin Whittaker on 27/02/2019 02:34:05

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