Gas release valve?

[Jac Brown]

They do have pressure reducers for the bigger stuff like barbeques.

[Steve Walker]

I presume that the needle valve and feed to it is sized to be very restrictive for the simple screw on burners.

The bigger ones fed by hose from a Calor cyclinder or the like have

28mBar regulators for butane or 37 mBar ones for propane. The different pressures allowing for the different calorific values of the two gases when using the same size jets, so allowing interchanging bottles depending upon the ambient temperatures. Butane won't gas off from the liquid on a cold day.

With high flows, such as a water heater (my parents' one needed a regulator capable of 4kg of per hour), the boiling off of the gas can cool the bottle too much and reduce gassing, so even in the summer, they had to use two butane bottles in parallel or a single propane one.

SteveW

[Commander Kinsey]

For example, I have a twin burner (Tilly) stove. It's fed from a butane cannister. Since I could operate one or both burners at different rates, there can't be a limiter anywhere that could work unless it's clever enough to adjust pressure independant of flow rate. Perhaps the pressure is quite high, but the taps to control the burners are what restricts it?

I wasn't aware of that, so I can't use a butane camping stove in winter?

[Steve Walker]

Or a separate restrictors before each valve - probably just the valve design though.

Basically correct. You may get away with it, but when temperatures are down to about 4°C, the cylinder cools a little further as the gas is used and it gets the bottle too cold to boil any more gas off. It is not actually a sudden cut-off, it is a reduction in the rate of boiling and so the gas flow is too low for the burners.

SteveW

[Commander Kinsey]

I didn't know that. I've never used a stove in cold temperatures. So anyone camping in winter uses propane?

[Commander Kinsey]

Well that's what I thought, and was made clear in my original post.

But.... I've seen them. They are not poles with a bright orange marker on top, they have a mechanism inside, they clearly do something with the gas.

[Bill Wright]

Yes, you have to. Otherwise no cooking or heating when it's cold.

Bill

[Andrew]

Somebody 'found' the underground fuel line when it ran through the grounds of a large estate, and they dug down, tapped into it and nicked loads of diesel.

[Scott Lurndal]

Yeah, the pipeline company never bothers to measure how much product enters and leaves the pipeline, so they'd never notice such a crime.

[Commander Kinsey]

I can't tell if that's sarcastic.

[Commander Kinsey]

I'm surprised they don't say on them they're restricted to warm days. Cold days are when you're more likely to use them!

I could understand them not mentioning it if the limit was below -20C or something. But someone said even 6C causes problems.

[Commander Kinsey]

Don't you have gas in the USA? That's real gas, not that liquid you put in your cars.

[Rod Speed]

Go and f*ck yourself.

[Commander Kinsey]

Percentages too difficult for you at school were they?

And learn basic chemistry. Gas floats, liquid pours.

[Andrew Gabriel]

The high pressure network represents a significant proportion of the country's stored gas.

[Commander Kinsey]

But is it usable? Say the input failed for a while, could we use up what's in the high pressure pipes? Could they transfer it all to low pressure at the normal rate?

[Tim+]

Why do you think gasometers have nearly all disappeared? Our reserves are now stored in the pipeline.

Tim

[Commander Kinsey]

I thought it was piped in from the north sea, Russia, whatever.

P.S. why did they always stink? Well the ones on Dock Street, Dundee did anyway.

So presumably this pipeline is variable pressure?

[Chris J Dixon]

" Methodology

We determine NTS linepack by calculating the volume of gas within the NTS pipelines, using a network model and instantaneous measurements. The model contains a database of NTS pipeline diameters and lengths, updated as required to accommodate changes to the network.

The NTS is divided into pipeline sections, and the volume of gas within each section is determined by multiplication of the pipe free volume by the ratio of the gas density at actual conditions to the gas density at standard temperature and pressure.

The actual gas density is computed from a standard equation of state applying pressure, temperature and specific gravity data. The pressure is derived from telemetered measurements at the beginning and end of the pipeline section, and an average network gas temperature is applied. The specific gravity is determined from telemetered measurements at NTS entry and exit points according to a fixed mapping arrangement. The network model then summates the calculated volume of gas for each pipeline section to compute total NTS linepack.

The opening NTS linepack for a gas day, which is equivalent to the closing NTS linepack for the preceding gas day, will be the volume calculated by the network model as close to the start of the gas day as possible."

From this page

you can reach

which is a graph showing the pressure variations.

Chris

[Commander Kinsey]

Why did we used to need gasometers? Surely a high pressure pipeline isn't something really technologically advanced?