One for the Corgis

[WDIK]

Sounds to me that this post is degenerating into a load of bo***cks, with some trying to score points with ridiculous equations that mean jack sh*t in the real world

what equations?

now im really getting confused


again

 

[doitall]

Being serious for a second

Iv'e often thought that one of simond's accumulators could be very handy where low pressure is a problem.

Perhaps something for the inventors to make their fortune with.

A mini gasometer under the kitchen sink.

 

[ChrisR]

Yes. I got that stuck in my head until someom=ne poointed out that you're measuring it relative to atmosphere so you're getting

1015
1021
of what you should, which is 99.4% of it!
You could always freeze your meter to squash more in!

can you explain that more clearly?

so far I imagine, from situations ive seen, where due to inadequately sized supply pipework there has been an inlet pressure as low as 13 mbar,
yet due to the construction of meters they measure volume.
so 1 cu ft of gas is the same volume at 20 mbar as it is at 10 mbar.

reduce the contained pressure to atmospheric pressure then the 20mb has twice the volume as the 10mb.

i would postulate that the calorific value of the 20mb is twice that of the 10mb.

Yes that's exactly what I used to think - but the 20mbar is relative to one atmosphere, so its absolute pressure is 1020 mbar (say). Or it could be 1010 mbar or 1015mbar if low.
ie the other end of the U tube is open!

See

You do get a bit less gas at altitude, because the normal atmospheric pressure is lower. But not much.


I've seen some really odd meter behaviour which supports what I used to think - I can't explain it! Imaginary, perhaps.

 

[WDIK]

wow that was the lousiest explaimantion ive read for a while

ive thought about on and off through the day.

then there was a shaft of light from the heavens and the penny dropped.

for a U tube to be in balance it must have and equal pressure or weight at both ends.

so therefore at zero there must be 1 atmosphere pressure at both ends.

so for the mano to read 20mb gas, that means @ zero the gas would be @ absolute pressure of an equal pressure of 1 atmosphere,
so to read 20mb it is 20mb + 1 atmosphere.

but then is that usable gas?

i would say it wasnt, because if the absolute pressure were 1 amosphere then the gauge would read zero.

as pressure is the moving force for the gas to move the pressure has to exceed atmospheric pressure, in this instance by 20mb.

take that away and the flow stops.

the gas moving is the only gas being used, the gas at atmospheric pressure is the gas that would occupy the pipe wether it be methane or air or any other gasious medium to prevent the pipe from collasping under the weight of atmospheric pressure

anyway meters measure volume and the movement pressure in this instance is 20mb.

if atmosphere were lowered the relative pressure read would increase.

 

[WDIK]

anyone care to join in?

 

[tabs]

When doing a TT you are measuring static pressure. AS the governor gives a constant pressure at the entry to the "closed system" Boyles shows that the meter will always measure the same quantity of gas(at a constant temp).

As someon earlier said changing temperature will either give you less or more gas as measured through the meter(Charles Law- as long as the pressure remains constant)

 

[Bambergaspipe]

Remember things like cookers and fires may have no appliance regulator at all, so they would all need changing..

I`ll remember that on my next back boiler service!!!! Back to school...........

 

[ChrisR]

wow that was the lousiest explaimantion ive read for a while

Good grief you must be nearly as thick as Bambi! He's talking rubbish as usual!

I said the other end of the U gauge is open to atmosphere...

You've got a mental block about this I reckon WDIK. Forget about driving force. Eg with a zero governor that's not even in the picture.

Think of the gas as water in a reservoir. You get it by making a notch/hole in the dam wall. You measure it in buckets, however fast it comes over or what pressure it's at through a hole. You pay by the bucket. Because it's gas and not liquid, it compresses a bit, but the difference between atmospheric + 10 mbar and atmospheric + 20 mbar ain't much.

 

[WDIK]

read it again Chris

the atmospheric element of the pressure is irrelevant and is only there because otherwise the pipe would colapse.


I'll ignore the slur

 

[simond]

Doitall wrote;

Iv'e often thought that one of simond's accumulators could be very handy where low pressure is a problem.

Perhaps something for the inventors to make their fortune with.

Very funny. But how many times do I have to remind you that an accumulator boosts flow, not pressure?

You could make a booster that uses mains water pressure in an accumulator vessel to boost the gas pressure. It could act as a buffer for higher power instantaneous water heaters in domestic use.

 

[Softus]

so for the mano to read 20mb gas, that means @ zero the gas would be @ absolute pressure of an equal pressure of 1 atmosphere,
so to read 20mb it is 20mb + 1 atmosphere.

but then is that usable gas?

Yes.

the gas moving is the only gas being used, the gas at atmospheric pressure is the gas that would occupy the pipe wether it be methane or air or any other gasious medium to prevent the pipe from collasping under the weight of atmospheric pressure

I can't tell if you're joking or not, but emptying a copper pipe of gas, or air, or everything (i.e. creating a vacuum inside it) would not result in the pipe collapsing.

 

[Bambergaspipe]

so for the mano to read 20mb gas, that means @ zero the gas would be @ absolute pressure of an equal pressure of 1 atmosphere,
so to read 20mb it is 20mb + 1 atmosphere.

but then is that usable gas?

Yes.

the gas moving is the only gas being used, the gas at atmospheric pressure is the gas that would occupy the pipe wether it be methane or air or any other gasious medium to prevent the pipe from collasping under the weight of atmospheric pressure

I can't tell if you're joking or not, but emptying a copper pipe of gas, or air, or everything (i.e. creating a vacuum inside it) would not result in the pipe collapsing.

I think the post excludes the likes of you Softus, i.e unqualified.

It says `` one for the Corgi`s`` not ``òne for the wannabes`` Soz fellah...mebbe next year.......Heh...Heh..

 

[ChrisR]

read it again Chris

DOn't need to mate, this is kindergarten stuff

I'll ignore the slur

But I need to rub it in so you feel annoyed
I felt dumb when I realised I'd been getting it wrong, too.

the atmospheric element of the pressure is irrelevant and is only there because otherwise the pipe would colapse.

Nonsense!
You pay for the stuff because they deliver it to your house, not because they pressurise it!
Same as water...

 

[ChrisR]

Given the increasing demands for higher gas volumes why are we still working with the relatively low mb operating pressure which was specified decades ago when demands were less.

Why not legislate for an increase in supply pressure and utilise point of use regulation (as regulators are cheap as chips) instead and negate the need to rip out miles of copper every time a new boiler is fitted?

MW

Because miles of copper is never ripped out every time a boiler is fitted, a new boiler is fitted new for old usually & the gas supply rarely changes, the rest of this post and the fools pontificating over it are the same as your theory..........Ridiculous..

Bambi porobably sticks new boilers in on undersized pipes all the time. He clearly doesn't understand Megawatt's point which is a perfectly reasonable question.

 

[ChrisR]

You could make a booster that uses mains water pressure in an accumulator vessel to boost the gas pressure. It could act as a buffer for higher power instantaneous water heaters in domestic use.

Accumulators run out, which is why they're not much good.
In this case when it happened, the flames could go out and people could die. Wouldn't worry Simon though - another sale, wahae.