I thought I'd share by exerience of making a foolish and potentially
dangerous mistake. I am replumbing the house at the moment and there
are some 'dead end' pipes that lead up to the bathroom but are
presently capped off with compression stop-end fittings like this:

http://www.screwfix.com/prods/50419/...22mm-Pack-of-5

Anyway, these pipes were pressurised at mains pressure but had a lot
of air in them. I thought it would be a good idea to bleed the air
out. So I thought: "I'll just slacken the stop end compression nut a
tiny bit and let the air hiss out, then tighten it up again."

Well, as soon as I slackened the nut a little there was a loud BANG
and the whole fitting shot off at high speed. Luckily it did no
damage. This was followed by a lot of water!

I now realise of course that once the fitting was slackened it did not
take much force to slide the olive off the end of the pipe. The loud
bang was because of all the compressed air in the pipe -about 1 litre
of air at 70 Bar.

I felt really foolish. Learn from my mistake!

Robert

RobertL wrote:

I now realise of course that once the fitting was slackened it did not
take much force to slide the olive off the end of the pipe. The loud
bang was because of all the compressed air in the pipe -about 1 litre
of air at 70 Bar.

1000psi mains?

If the fitting had been made off Correctly, the Olive should had deformed
the Tube and that would not of happened.

And where did you get 70Bar (that is over 1000 psi)

Baz

"RobertL" wrote in message
...

I thought I'd share by exerience of making a foolish and potentially
dangerous mistake. I am replumbing the house at the moment and there
are some 'dead end' pipes that lead up to the bathroom but are
presently capped off with compression stop-end fittings like this:

http://www.screwfix.com/prods/50419/...22mm-Pack-of-5

Anyway, these pipes were pressurised at mains pressure but had a lot
of air in them. I thought it would be a good idea to bleed the air
out. So I thought: "I'll just slacken the stop end compression nut a
tiny bit and let the air hiss out, then tighten it up again."

Well, as soon as I slackened the nut a little there was a loud BANG
and the whole fitting shot off at high speed. Luckily it did no
damage. This was followed by a lot of water!

I now realise of course that once the fitting was slackened it did not
take much force to slide the olive off the end of the pipe. The loud
bang was because of all the compressed air in the pipe -about 1 litre
of air at 70 Bar.

I felt really foolish. Learn from my mistake!

Robert

In article
,
RobertL wrote:
I now realise of course that once the fitting was slackened it did not
take much force to slide the olive off the end of the pipe.

A properly fitted compression fitting doesn't allow the olive to 'slide
off'

The loud bang was because of all the compressed air in the pipe -about
1 litre of air at 70 Bar.

The entire system would explode with pressure anywhere near 70 bar. Mains
is rarely above 3 bar.

--
*Not all men are annoying. Some are dead.

Dave Plowman London SW
To e-mail, change noise into sound.

This has got to be wrong, 70 PSI (pounds per square inch) maybe ?

Even this (70PSI) seems high.

(Many water boards only guarantee a minimum of 1 Bar (about 14.7PSI))

On Jan 8, 11:04*am, "Dave Plowman (News)"
wrote:
In article
,
* *RobertL wrote:

I now realise of course that once the fitting was slackened it did not
take much force to slide the olive off the end of the pipe.

A properly fitted compression fitting doesn't allow the olive to 'slide
off'

*The loud bang was because of all the compressed air in the pipe -about
1 litre of air at 70 Bar.

The entire system would explode with pressure anywhere near 70 bar. Mains
is rarely above 3 bar.


oops yes sorry I meant 70 metres of head - although maybe it's more
likely to be 30.

R

On 8 Jan, 11:09, "Ian French" wrote:

Even this (70PSI) seems high.

(Many water boards only guarantee a minimum of 1 Bar (about 14.7PSI))

We often get 80PSI here in Bristol (certainly always above 70PSI).

Mathew

On Thu, 08 Jan 2009 11:04:49 +0000 (GMT) someone who may be "Dave
Plowman (News)" wrote this:-

The entire system would explode with pressure anywhere near 70 bar. Mains
is rarely above 3 bar.

The static pressure at my house is 4.5 to 5.5 bar depending on the
time of day.



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

Dave Plowman (News) coughed up some electrons that declared:

In article
,
RobertL wrote:
I now realise of course that once the fitting was slackened it did not
take much force to slide the olive off the end of the pipe.

A properly fitted compression fitting doesn't allow the olive to 'slide
off'

The loud bang was because of all the compressed air in the pipe -about
1 litre of air at 70 Bar.

The entire system would explode with pressure anywhere near 70 bar. Mains
is rarely above 3 bar.


Worst case I've seen consistently is 7.5 bar.

RobertL coughed up some electrons that declared:


oops yes sorry I meant 70 metres of head - although maybe it's more
likely to be 30.

That's 7bar and 3bar respectively.

"RobertL" wrote in message
...

I thought I'd share by exerience of making a foolish and potentially
dangerous mistake. I am replumbing the house at the moment and there
are some 'dead end' pipes that lead up to the bathroom but are
presently capped off with compression stop-end fittings like this:

http://www.screwfix.com/prods/50419/...22mm-Pack-of-5

Anyway, these pipes were pressurised at mains pressure but had a lot
of air in them. I thought it would be a good idea to bleed the air
out. So I thought: "I'll just slacken the stop end compression nut a
tiny bit and let the air hiss out, then tighten it up again."

Well, as soon as I slackened the nut a little there was a loud BANG
and the whole fitting shot off at high speed. Luckily it did no
damage. This was followed by a lot of water!

I now realise of course that once the fitting was slackened it did not
take much force to slide the olive off the end of the pipe. The loud
bang was because of all the compressed air in the pipe -about 1 litre
of air at 70 Bar.

I felt really foolish. Learn from my mistake!

Robert

The olive is not meant to dig into the pipe. Depending on the water system
you have, you should have left the air in the pipe. IT acts as a shock
arrestor, until it dissolves.

On Jan 8, 11:04*am, "Dave Plowman (News)"
wrote:
In article
,
* *RobertL wrote:

I now realise of course that once the fitting was slackened it did not
take much force to slide the olive off the end of the pipe.

A properly fitted compression fitting doesn't allow the olive to 'slide
off'


Are you sure? Here's a tool designed to slide off olives:

http://www.monument-tools.com/innovation.htm

How much force does this gadget use to slide off the olive? At a
guess its something like 5 Newtons (force from thumb) x 20 (guess at
ratio of distance moved by thumb/distance moved by pusher on olive). =
100 Newtons.

What force does the water and compressed air exert? 500,000 Pascals
(5 Bar) * 2/10000 sq m (2 sq cm) = 100 Newtons.

So the force of the water in a slackened compression fitting is about
the same as the force of an olive extractor. So it's quite posisble
for a properly fitted fitting to blow off when slackened in this way.

Robert

"Doctor Drivel" wrote in message
...
SNIP
The olive is not meant to dig into the pipe.
SNIP

Oh Yes it is!!

Baz

On Thu, 8 Jan 2009 14:26:53 UTC, "Baz" wrote:


"Doctor Drivel" wrote in message
...
SNIP
The olive is not meant to dig into the pipe.
SNIP

Oh Yes it is!!

Agreed. Drivel keeps the olive in place by relying on the hacksaw burrs.

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
http://www.diybanter.com

Bob Eager wrote:
On Thu, 8 Jan 2009 14:26:53 UTC, "Baz" wrote:

"Doctor Drivel" wrote in message
...
SNIP
The olive is not meant to dig into the pipe.
SNIP

Oh Yes it is!!

Agreed. Drivel keeps the olive in place by relying on the hacksaw burrs.

To be fair, on steel pipes, it doesn't dig in that far...

"Baz" wrote in message
...

"Doctor Drivel" wrote in message
...
SNIP
The olive is not meant to dig into the pipe.
SNIP

Oh Yes it is!!

You need to get to know more about pipe fittings.

"Doctor Drivel" wrote in message
...

"Baz" wrote in message
...

"Doctor Drivel" wrote in message
...
SNIP
The olive is not meant to dig into the pipe.
SNIP

Oh Yes it is!!

You need to get to know more about pipe fittings.

I doubt very much, that anyone on this NG knows any more than me about "Pipe
Fittings".

For one you don't. Do you even know the difference between "Pipe" and
"Tube"??

Are you the fool who had that silly thread going about "Push on Fittings" a
few years ago?

Baz

"The Natural Philosopher" wrote in message
...
Bob Eager wrote:
On Thu, 8 Jan 2009 14:26:53 UTC, "Baz" wrote:

"Doctor Drivel" wrote in message
...
SNIP
The olive is not meant to dig into the pipe.
SNIP

Oh Yes it is!!

Agreed. Drivel keeps the olive in place by relying on the hacksaw burrs.

To be fair, on steel pipes, it doesn't dig in that far...

Ferrules for Steel "Pipe" will have an "Edge" to bite into the "Pipe".

Baz

Baz wrote:
"Doctor Drivel" wrote in message
...

"Baz" wrote in message
...

"Doctor Drivel" wrote in message
...
SNIP
The olive is not meant to dig into the pipe.
SNIP

Oh Yes it is!!

You need to get to know more about pipe fittings.

I doubt very much, that anyone on this NG knows any more than me
about "Pipe Fittings".

For one you don't. Do you even know the difference between "Pipe" and
"Tube"??

Please educate the uneducated of the group then Baz as to what is the main
difference "between "Pipe" and "Tube"" as defined for plumbing and heatings
applications (and if you wish, engineering as well [such as gas and oil
conveyance]).

Unbeliever

RobertL wrote:
On Jan 8, 11:04 am, "Dave Plowman (News)"
wrote:
In article
,
RobertL wrote:

I now realise of course that once the fitting was slackened it did
not take much force to slide the olive off the end of the pipe.

A properly fitted compression fitting doesn't allow the olive to
'slide off'


Are you sure? Here's a tool designed to slide off olives:

http://www.monument-tools.com/innovation.htm

How much force does this gadget use to slide off the olive? At a
guess its something like 5 Newtons (force from thumb) x 20 (guess at
ratio of distance moved by thumb/distance moved by pusher on olive). =
100 Newtons.

Errm no. I have one and it takes a sh*t load of force to remove most
olives. Usually a boc spanner on the tommy bar to get enough leverage.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

In article ,
RobertL writes:

I thought I'd share by exerience of making a foolish and potentially
dangerous mistake. I am replumbing the house at the moment and there
are some 'dead end' pipes that lead up to the bathroom but are
presently capped off with compression stop-end fittings like this:

http://www.screwfix.com/prods/50419/...22mm-Pack-of-5

Anyway, these pipes were pressurised at mains pressure but had a lot
of air in them. I thought it would be a good idea to bleed the air
out. So I thought: "I'll just slacken the stop end compression nut a
tiny bit and let the air hiss out, then tighten it up again."

Well, as soon as I slackened the nut a little there was a loud BANG
and the whole fitting shot off at high speed. Luckily it did no
damage. This was followed by a lot of water!

I now realise of course that once the fitting was slackened it did not
take much force to slide the olive off the end of the pipe. The loud
bang was because of all the compressed air in the pipe -about 1 litre
of air at 70 Bar.

The bang was more likely due to the momentum of a now fast moving
mass of water banging into the fitting. A friend managed to burst
a ballcock valve this way. With water being effectively incompressible,
the momentary pressure at the fitting would well exceed the static
water pressure.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Thu, 8 Jan 2009 02:35:57 -0800 (PST), RobertL
wrote:


I thought I'd share by exerience of making a foolish and potentially
dangerous mistake. I am replumbing the house at the moment and there
are some 'dead end' pipes that lead up to the bathroom but are
presently capped off with compression stop-end fittings like this:

http://www.screwfix.com/prods/50419/...22mm-Pack-of-5

Anyway, these pipes were pressurised at mains pressure but had a lot
of air in them. I thought it would be a good idea to bleed the air
out. So I thought: "I'll just slacken the stop end compression nut a
tiny bit and let the air hiss out, then tighten it up again."

Well, as soon as I slackened the nut a little there was a loud BANG
and the whole fitting shot off at high speed. Luckily it did no
damage. This was followed by a lot of water!

I now realise of course that once the fitting was slackened it did not
take much force to slide the olive off the end of the pipe. The loud
bang was because of all the compressed air in the pipe -about 1 litre
of air at 70 Bar.

I felt really foolish. Learn from my mistake!

Robert

Don't s'pose you videoed it ? :-)

On Jan 8, 8:50*pm, "The Medway Handyman"
wrote:
RobertL wrote:
On Jan 8, 11:04 am, "Dave Plowman (News)"
wrote:
In article
,
RobertL wrote:

I now realise of course that once the fitting was slackened it did
not take much force to slide the olive off the end of the pipe.

A properly fitted compression fitting doesn't allow the olive to
'slide off'

Are you sure? * *Here's a tool designed to slide off olives:

http://www.monument-tools.com/innovation.htm

How much force does this gadget use to slide off the olive? * At a
guess its something like 5 Newtons (force from thumb) *x 20 (guess at
ratio of distance moved by thumb/distance moved by pusher on olive). =
100 Newtons.

Errm no. *I have one and it takes a sh*t load of force to remove most
olives. *Usually a boc spanner on the tommy bar to get enough leverage.


Oh dear, there's something wrong with my compression fitting
tightening technique then :-(

R

"Baz" wrote in message
...

"Doctor Drivel" wrote in message
...

"Baz" wrote in message
...

"Doctor Drivel" wrote in message
...
SNIP
The olive is not meant to dig into the pipe.
SNIP

Oh Yes it is!!

You need to get to know more about pipe fittings.

I doubt very much, that anyone on this NG knows any more than me about
"Pipe Fittings".

That person is me.

On 8 Jan, 23:40, (Andrew Gabriel) wrote:

The bang was more likely due to the momentum of a now fast moving
mass of water banging into the fitting.

Agreed. A nice, fast hydraulic slide hammer.

Ian

In article ,
Doctor Drivel wrote:
I doubt very much, that anyone on this NG knows any more than me about
"Pipe Fittings".

That person is me.

Hacksaw. I rest my case.

--
*We waste time, so you don't have to *

Dave Plowman London SW
To e-mail, change noise into sound.

"Doctor Drivel" wrote in message
...

"Baz" wrote in message
...

"Doctor Drivel" wrote in message
...

"Baz" wrote in message
...

"Doctor Drivel" wrote in message
...
SNIP
The olive is not meant to dig into the pipe.
SNIP

Oh Yes it is!!

You need to get to know more about pipe fittings.

I doubt very much, that anyone on this NG knows any more than me about
"Pipe Fittings".

That person is me.


I noticed that you snipped the following, without marking it.
"Are you the fool who had that silly thread going about "Push on Fittings" a
few years ago?"

Baz

On Jan 9, 1:53 pm, "Baz" wrote:
You need to get to know more about pipe fittings.

I doubt very much, that anyone on this NG knows any more than me about
"Pipe Fittings".

Can I repeat "Unbeliever"s request for an explanation of the
difference between tube and pipe? Some of us here are always
interested to learn technical esoterica.

"Martin Bonner" wrote in message
...
On Jan 9, 1:53 pm, "Baz" wrote:
You need to get to know more about pipe fittings.

I doubt very much, that anyone on this NG knows any more than me about
"Pipe Fittings".

Can I repeat "Unbeliever"s request for an explanation of the
difference between tube and pipe? Some of us here are always
interested to learn technical esoterica.

Well, a tube is an electronic device that's used to show moving pictures in
one's home, and a pipe is what Sherlock Holmes stuck in his mouth. Quite
different to the pipe/tube he stuck into Watson.

"Dave Plowman (News)" wrote in message
...
In article ,
Doctor Drivel wrote:

I doubt very much, that anyone on this NG knows any more than me about
"Pipe Fittings".

That person is me.

Please eff off as you a total idiotic plantpot.

"Martin Bonner" wrote in message
...
On Jan 9, 1:53 pm, "Baz" wrote:
You need to get to know more about pipe fittings.

I doubt very much, that anyone on this NG knows any more than me about
"Pipe Fittings".

Can I repeat "Unbeliever"s request for an explanation of the
difference between tube and pipe? Some of us here are always
interested to learn technical esoterica.

He thinks push-fit is fab too.

In article ,
Doctor Drivel wrote:
I doubt very much, that anyone on this NG knows any more than me
about "Pipe Fittings".

That person is me.

Please eff off as you a total idiotic plantpot.

You've certainly got that right for once.

--
*No husband has ever been shot while doing the dishes *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Doctor Drivel wrote:
I doubt very much, that anyone on this NG knows any more than me
about "Pipe Fittings".

That person is me.

Please eff off as you are a total idiotic plantpot.

You've certainly got that right for once.

I did, so, please eff off as you are a total idiotic plantpot.

On 9 Jan, 14:58, "Grumps" wrote:
Can I repeat "Unbeliever"s request for an explanation of the
difference between tube and pipe? *Some of us here are always
interested to learn technical esoterica.

Tube; OD is the critical dimension 15mm, 22mm copper.
Pipe ID is critical 1/2", 1", 25mm, 20mm steel.
Old 1/2" imperial copper was pipe, so the OD is nearly the same as
15mm metric copper tube.

Martin Bonner wrote:
On Jan 9, 1:53 pm, "Baz" wrote:
You need to get to know more about pipe fittings.

I doubt very much, that anyone on this NG knows any more than me
about "Pipe Fittings".

Can I repeat "Unbeliever"s request for an explanation of the
difference between tube and pipe? Some of us here are always
interested to learn technical esoterica.


Thought Baz wouldn't come back so roughly:

*PIPE*

Is a tube or hollow cylinder used to convey materials or as a structural
component. The terms pipe and tube are almost interchangeable. A pipe is
generally specified by the internal diameter (ID) whereas a tube is usually
defined by the outside diameter (OD) but may be specified by any combination
of dimensions (OD, ID, wall thickness). A tube is often made to custom sizes
and may often have more specific sizes and tolerances than pipe. Also, the
term tubing can be applied to non-cylindrical shapes (i.e. square tubing).
The term tube is more widely used in the United States, whereas pipe is more
common elsewhere in the world.

Both pipe and tube imply a level of rigidity and permanence, whereas a hose
is usually portable and flexible. Pipe may be specified by standard pipe
size designations, such as nominal pipe size (in the United States), or by
nominal, outside, or inside diameter and wall thickness. Many industrial and
government standards exist for the production of pipe and tubing.



*TUBING*

Is a pipe or hollow cylinder for the conveyance of fluids (liquids or
gases). The terms 'pipe' and 'tubing' are almost interchangeable, although
minor distinctions exist (generally, "tubing" implies tighter engineering
requirements than "pipe"). Both "pipe" and "tube" imply a level of rigidity
and permanence, whereas a "hose" is usually portable and flexible. Tubing
and pipe may be specified by standard pipe size designations, e.g. Nominal
Pipe Size - or by nominal outside or inside diameter and/or wall thickness.
The actual dimensions of pipe are usually not the nominal dimensions (i.e.,
a "1-inch" pipe will not actually measure 1" in either outside or inside
diameter) - whereas many types of tubing are specified by actual I.D., O.D.,
and/or wall thickness. There are many industry and government standards for
pipe and tubing.

Please note that this is not my own work (taken from sections of
Wikipedia.com to save time) - and just too damned lazy to write one up.

But if Baz still wants to comment or correct - then great.



Disbeliever

Onetap wrote:

Tube; OD is the critical dimension 15mm, 22mm copper.
Pipe ID is critical 1/2", 1", 25mm, 20mm steel.
Old 1/2" imperial copper was pipe, so the OD is nearly the same as
15mm metric copper tube.

They say we learn something new every day....
I hadn't learn't anything new for about a week but I think this makes up
for it in one go.

Thankyou.