"rangerssuck" wrote in message
...
On Tuesday, May 9, 2017 at 9:29:09 AM UTC-4, Jim Wilkins wrote:
"rangerssuck" wrote in message
...
So, I got to thinking that there might be a better place than AGL,
Praxair or Aigas to get the nitrogen or Argon. A couple of minutes
with google turned up a welding supply / gas supply about a mile
from
my house. They will rent a 330cf cylinder for $4.00 per month and
fill
it with nitrogen for $29 or argon for $65.

This is way cheaper than I would expect to pay at any of the big
shops, and couldn't be much more convenient. A huge bonus.

==========
Once it holds a vacuum I'd make a rough estimate of the volume with
dried compressed air, then a better one by evacuating it and
filling
from a nitrogen tank nearest the estimated cf capacity. The
(absolute)
pressure drop in the cylinder and the rise in the piping give you
the
volume ratio. The more the gauges change, the better the
resolution.
https://en.wikipedia.org/wiki/Boyle%27s_Law

-jsw

That's a good one, but it requires that you know the actual cf in
the tank first. I have no idea how accurately that gets measured
when tanks are filled.

You can look up the cylinder volume and measure the pressure.

On Wed, 10 May 2017 14:00:52 -0400, Carl Ijames wrote:

"rangerssuck" wrote in message
...

The refrigerant pipes in a typical rink are about 10 or 11 miles long
(seriously), and are (sometimes) 5/8 OD thinwall steel, but that's a
variable.

================================================== ==================================================

Just as a sanity check when you do the pressurize with nitrogen test, I
get a volume of 72 cu ft or 2039 L for 10 miles of 1/2" ID tubing. At
STP, 0 C and 101 kPa nitrogen has a density of 1.25 g/L so at STP 72 cu
ft would weigh 5.62 lbs (I'm ignoring the difference between room
temperature and STP for this estimate :-)). If you start at atmospheric
pressure you would need 3x72 cu ft = 216 cu ft to reach 44.1 psig which
should be completely safe since the vapor pressure of R22 at 75 F is 132
psig. So you will need at least a couple of tanks of nitrogen on hand
to be safe, and a refrigeration scale that can do 0.1 lbs at the weight
of a full tank of nitrogen with regulator should let you get an answer
in the 5-10% range. Have fun.

Man, I just know that if I tried this I'd be lucky to be off by a factor
of two, and not 10 or something.

Good luck, and have fun.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I'm looking for work -- see my website!

"Tim Wescott" wrote in message
...
On Wed, 10 May 2017 14:00:52 -0400, Carl Ijames wrote:

"rangerssuck" wrote in message
...

The refrigerant pipes in a typical rink are about 10 or 11 miles
long
(seriously), and are (sometimes) 5/8 OD thinwall steel, but that's
a
variable.

================================================== ==================================================

Just as a sanity check when you do the pressurize with nitrogen
test, I
get a volume of 72 cu ft or 2039 L for 10 miles of 1/2" ID tubing.
At
STP, 0 C and 101 kPa nitrogen has a density of 1.25 g/L so at STP
72 cu
ft would weigh 5.62 lbs (I'm ignoring the difference between room
temperature and STP for this estimate :-)). If you start at
atmospheric
pressure you would need 3x72 cu ft = 216 cu ft to reach 44.1 psig
which
should be completely safe since the vapor pressure of R22 at 75 F
is 132
psig. So you will need at least a couple of tanks of nitrogen on
hand
to be safe, and a refrigeration scale that can do 0.1 lbs at the
weight
of a full tank of nitrogen with regulator should let you get an
answer
in the 5-10% range. Have fun.

Man, I just know that if I tried this I'd be lucky to be off by a
factor
of two, and not 10 or something.

Good luck, and have fun.
Tim Wescott

=========================
Yes, I tend to practice an experiment cheaply to find issues with my
equipment and technique, before making careful measurements. I no
longer have access to recently calibrated lab instruments and the
motley assortment of surplus I have at home doesn't all agree too
well.

However my flea-market 1970's Fluke 4-1/2 and 5-1/2 digit bench meters
are still within spec when measuring a 10V calibration standard.
-jsw

On Wednesday, May 10, 2017 at 6:40:09 PM UTC-4, Jim Wilkins wrote:
"Tim Wescott" wrote in message
...
On Wed, 10 May 2017 14:00:52 -0400, Carl Ijames wrote:

"rangerssuck" wrote in message
...

The refrigerant pipes in a typical rink are about 10 or 11 miles
long
(seriously), and are (sometimes) 5/8 OD thinwall steel, but that's
a
variable.

================================================== ==================================================

Just as a sanity check when you do the pressurize with nitrogen
test, I
get a volume of 72 cu ft or 2039 L for 10 miles of 1/2" ID tubing.
At
STP, 0 C and 101 kPa nitrogen has a density of 1.25 g/L so at STP
72 cu
ft would weigh 5.62 lbs (I'm ignoring the difference between room
temperature and STP for this estimate :-)). If you start at
atmospheric
pressure you would need 3x72 cu ft = 216 cu ft to reach 44.1 psig
which
should be completely safe since the vapor pressure of R22 at 75 F
is 132
psig. So you will need at least a couple of tanks of nitrogen on
hand
to be safe, and a refrigeration scale that can do 0.1 lbs at the
weight
of a full tank of nitrogen with regulator should let you get an
answer
in the 5-10% range. Have fun.

Man, I just know that if I tried this I'd be lucky to be off by a
factor
of two, and not 10 or something.

Good luck, and have fun.
Tim Wescott

=========================
Yes, I tend to practice an experiment cheaply to find issues with my
equipment and technique, before making careful measurements. I no
longer have access to recently calibrated lab instruments and the
motley assortment of surplus I have at home doesn't all agree too
well.

However my flea-market 1970's Fluke 4-1/2 and 5-1/2 digit bench meters
are still within spec when measuring a 10V calibration standard.
-jsw

I've got 3 meters I'd like to check for calibration. Is that 10V calibration standard something that costs an arm and a leg?

Garrett

"Garrett Fulton" wrote in message
...
On Wednesday, May 10, 2017 at 6:40:09 PM UTC-4, Jim Wilkins wrote:
................
However my flea-market 1970's Fluke 4-1/2 and 5-1/2 digit bench
meters
are still within spec when measuring a 10V calibration standard.
-jsw

I've got 3 meters I'd like to check for calibration. Is that 10V
calibration standard something that costs an arm and a leg?

Garrett

https://www.amazon.com/DROK-Precisio.../dp/B00NL419KW
The reference IC is really an AD584.
Its hand-written label indicates that it measured 10.00222V on an
Agilent 34401A at 21C in 2015. My Fluke 8800A (no cal?) shows
10.0017/18, the Fluke 8600A (1995 cal) shows 10.002V.

-jsw

On Wednesday, May 10, 2017 at 2:02:25 PM UTC-4, Carl Ijames wrote:
"rangerssuck" wrote in message
...

The refrigerant pipes in a typical rink are about 10 or 11 miles long
(seriously), and are (sometimes) 5/8 OD thinwall steel, but that's a
variable.
================================================== ==================================================

Just as a sanity check when you do the pressurize with nitrogen test, I get
a volume of 72 cu ft or 2039 L for 10 miles of 1/2" ID tubing. At STP, 0 C
and 101 kPa nitrogen has a density of 1.25 g/L so at STP 72 cu ft would
weigh 5.62 lbs (I'm ignoring the difference between room temperature and STP
for this estimate :-)). If you start at atmospheric pressure you would need
3x72 cu ft = 216 cu ft to reach 44.1 psig which should be completely safe
since the vapor pressure of R22 at 75 F is 132 psig. So you will need at
least a couple of tanks of nitrogen on hand to be safe, and a refrigeration
scale that can do 0.1 lbs at the weight of a full tank of nitrogen with
regulator should let you get an answer in the 5-10% range. Have fun.

--
Regards,
Carl Ijames

I've got 300cf of nitrogen in one big tank, an accurate temperature sensor buried in the concrete and a scale that's good to 1% or so at the weight of this tank.

And thanks, I do expect this to be at least a little fun.

You're doing better than I am

I WORKED for Praxair, and my extra special employee discount was .69c
per day tank rental, and .55c cf for argon.

Needless to say, passed on THAT fine deal. Quit the company, too




So, I got to thinking that there might be a better place than AGL, Praxair or
Aigas to get the nitrogen or Argon. A couple of minutes with google
turned up a welding supply / gas supply about a mile
from my house. They will rent a 330cf cylinder for $4.00 per month and
fill it with nitrogen for $29 or argon for $65.


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

On Wednesday, May 10, 2017 at 4:02:06 PM UTC-4, Jim Wilkins wrote:
"rangerssuck" wrote in message
...
On Tuesday, May 9, 2017 at 9:29:09 AM UTC-4, Jim Wilkins wrote:
"rangerssuck" wrote in message
...
So, I got to thinking that there might be a better place than AGL,
Praxair or Aigas to get the nitrogen or Argon. A couple of minutes
with google turned up a welding supply / gas supply about a mile
from
my house. They will rent a 330cf cylinder for $4.00 per month and
fill
it with nitrogen for $29 or argon for $65.

This is way cheaper than I would expect to pay at any of the big
shops, and couldn't be much more convenient. A huge bonus.

==========
Once it holds a vacuum I'd make a rough estimate of the volume with
dried compressed air, then a better one by evacuating it and
filling
from a nitrogen tank nearest the estimated cf capacity. The
(absolute)
pressure drop in the cylinder and the rise in the piping give you
the
volume ratio. The more the gauges change, the better the
resolution.
https://en.wikipedia.org/wiki/Boyle%27s_Law

-jsw

That's a good one, but it requires that you know the actual cf in
the tank first. I have no idea how accurately that gets measured
when tanks are filled.

You can look up the cylinder volume and measure the pressure.

I don't have anything to measure that kind of pressure with any significant accuracy or precision. My highest range transducer tops out at 500psi.

"rangerssuck" wrote in message
...
On Wednesday, May 10, 2017 at 4:02:06 PM UTC-4, Jim Wilkins wrote:
"rangerssuck" wrote in message
...
On Tuesday, May 9, 2017 at 9:29:09 AM UTC-4, Jim Wilkins wrote:
"rangerssuck" wrote in message
...
So, I got to thinking that there might be a better place than
AGL,
Praxair or Aigas to get the nitrogen or Argon. A couple of
minutes
with google turned up a welding supply / gas supply about a mile
from
my house. They will rent a 330cf cylinder for $4.00 per month
and
fill
it with nitrogen for $29 or argon for $65.

This is way cheaper than I would expect to pay at any of the big
shops, and couldn't be much more convenient. A huge bonus.

==========
Once it holds a vacuum I'd make a rough estimate of the volume
with
dried compressed air, then a better one by evacuating it and
filling
from a nitrogen tank nearest the estimated cf capacity. The
(absolute)
pressure drop in the cylinder and the rise in the piping give
you
the
volume ratio. The more the gauges change, the better the
resolution.
https://en.wikipedia.org/wiki/Boyle%27s_Law

-jsw

That's a good one, but it requires that you know the actual cf in
the tank first. I have no idea how accurately that gets measured
when tanks are filled.

You can look up the cylinder volume and measure the pressure.

I don't have anything to measure that kind of pressure with any
significant accuracy or precision. My highest range transducer tops
out at 500psi.

http://www.dfs-gauges.com/images/sup...s_accu_def.pdf

"Jim Wilkins" wrote in message
news
"rangerssuck" wrote in message
..................
You can look up the cylinder volume and measure the pressure.

I don't have anything to measure that kind of pressure with any
significant accuracy or precision. My highest range transducer tops
out at 500psi.

http://www.dfs-gauges.com/images/sup...s_accu_def.pdf

You may need this too:
https://www.concoa.com/cgachart.html
-jsw

On Thursday, May 11, 2017 at 6:38:03 AM UTC-4, Jim Wilkins wrote:
"Garrett Fulton" wrote in message
...
On Wednesday, May 10, 2017 at 6:40:09 PM UTC-4, Jim Wilkins wrote:
................
However my flea-market 1970's Fluke 4-1/2 and 5-1/2 digit bench
meters
are still within spec when measuring a 10V calibration standard.
-jsw

I've got 3 meters I'd like to check for calibration. Is that 10V
calibration standard something that costs an arm and a leg?

Garrett

https://www.amazon.com/DROK-Precisio.../dp/B00NL419KW
The reference IC is really an AD584.
Its hand-written label indicates that it measured 10.00222V on an
Agilent 34401A at 21C in 2015. My Fluke 8800A (no cal?) shows
10.0017/18, the Fluke 8600A (1995 cal) shows 10.002V.

-jsw

Thanks. Looks like it will work with 2 9V batteries. Ordered it.

Garrett

"Garrett Fulton" wrote in message
...
On Thursday, May 11, 2017 at 6:38:03 AM UTC-4, Jim Wilkins wrote:
.....
Thanks. Looks like it will work with 2 9V batteries. Ordered it.

Garrett

The slot in the board and the included clips can hold an A23 12V
battery, crudely. I bent the tabs at an angle to center the clips on
the battery. When my house warms up to 21C I'll measure it on the
5-1/2 digit meter at 12V and 18V.
-jsw

On Thu, 11 May 2017 21:44:34 -0400, "Jim Wilkins"
wrote:

"Garrett Fulton" wrote in message
...
On Thursday, May 11, 2017 at 6:38:03 AM UTC-4, Jim Wilkins wrote:
.....
Thanks. Looks like it will work with 2 9V batteries. Ordered it.

Garrett

The slot in the board and the included clips can hold an A23 12V
battery, crudely. I bent the tabs at an angle to center the clips on
the battery.

A23s are oddball batteries, which I've bought only once locally.
I have had to both bend the clips and tape the battery in for each of
my wireless doorbell transmitters over the years.

The Chiwanese brands give over a year's service for under a buck
apiece in a 5pk. Free shipping from Chiwan takes 4-6 weeks.

Duracells $3 a pop in 2pks gave a bit mo 1.5 years.

Energizers at $6 a pop in 2pks give zero life, since I won't pay that
ridiculous price.

--
Obstacles are those frightful things you
see when you take your eyes off your goal.
--Henry Ford

On Wednesday, May 10, 2017 at 5:45:33 PM UTC-4, Tim Wescott wrote:
On Wed, 10 May 2017 14:00:52 -0400, Carl Ijames wrote:

"rangerssuck" wrote in message
...

The refrigerant pipes in a typical rink are about 10 or 11 miles long
(seriously), and are (sometimes) 5/8 OD thinwall steel, but that's a
variable.

================================================== ==================================================

Just as a sanity check when you do the pressurize with nitrogen test, I
get a volume of 72 cu ft or 2039 L for 10 miles of 1/2" ID tubing. At
STP, 0 C and 101 kPa nitrogen has a density of 1.25 g/L so at STP 72 cu
ft would weigh 5.62 lbs (I'm ignoring the difference between room
temperature and STP for this estimate :-)). If you start at atmospheric
pressure you would need 3x72 cu ft = 216 cu ft to reach 44.1 psig which
should be completely safe since the vapor pressure of R22 at 75 F is 132
psig. So you will need at least a couple of tanks of nitrogen on hand
to be safe, and a refrigeration scale that can do 0.1 lbs at the weight
of a full tank of nitrogen with regulator should let you get an answer
in the 5-10% range. Have fun.

Man, I just know that if I tried this I'd be lucky to be off by a factor
of two, and not 10 or something.

Good luck, and have fun.

Back in grad school, I screwed up the conversion of Pascals
to atmospheres (or Torr?) by a factor of ten. And made my flow impedance
line x10 times too restrictive. ~x10 the work too. But once I found the
mistake in my notebook it was pretty easy to cut the line down to the
right impedance.

George H.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I'm looking for work -- see my website!

On Wed, 10 May 2017 18:49:23 -0700 (PDT), Garrett Fulton
wrote:



I've got 3 meters I'd like to check for calibration. Is that 10V calibration standard something that costs an arm and a leg?

Here you go.
http://www.voltagestandard.com/
John
John DeArmond
http://www.neon-john.com
http://www.tnduction.com
Tellico Plains, Occupied TN
See website for email address

On Thursday, May 11, 2017 at 6:38:03 AM UTC-4, Jim Wilkins wrote:
"Garrett Fulton" wrote in message
...
On Wednesday, May 10, 2017 at 6:40:09 PM UTC-4, Jim Wilkins wrote:
................
However my flea-market 1970's Fluke 4-1/2 and 5-1/2 digit bench
meters
are still within spec when measuring a 10V calibration standard.
-jsw

I've got 3 meters I'd like to check for calibration. Is that 10V
calibration standard something that costs an arm and a leg?

Garrett

https://www.amazon.com/DROK-Precisio.../dp/B00NL419KW
The reference IC is really an AD584.
Its hand-written label indicates that it measured 10.00222V on an
Agilent 34401A at 21C in 2015. My Fluke 8800A (no cal?) shows
10.0017/18, the Fluke 8600A (1995 cal) shows 10.002V.

-jsw

Nice find. Ordered one last night.

"Jim Wilkins" wrote in message
news
"Garrett Fulton" wrote in message
...
On Wednesday, May 10, 2017 at 6:40:09 PM UTC-4, Jim Wilkins wrote:
................
However my flea-market 1970's Fluke 4-1/2 and 5-1/2 digit bench
meters
are still within spec when measuring a 10V calibration standard.
-jsw

I've got 3 meters I'd like to check for calibration. Is that 10V
calibration standard something that costs an arm and a leg?

Garrett

https://www.amazon.com/DROK-Precisio.../dp/B00NL419KW
The reference IC is really an AD584.
Its hand-written label indicates that it measured 10.00222V on an
Agilent 34401A at 21C in 2015. My Fluke 8800A (no cal?) shows
10.0017/18, the Fluke 8600A (1995 cal) shows 10.002V.

-jsw

My house is now at 22C so as promised I rechecked theAD584 reference
against the 5-1/2 digit Fluke, after an hour warmup which decreased
the Fluke's initial 11 microVolt zero offset to +/-0.
Using an analog variable power supply, the Fluke reads +10.0018/19
with 12V powering the standard, and +10.0021/22 with 18V powering it.
It starts to droop below 10.0018 at less than 11.0V in.

I'd say that a more convenient 12V A23 battery clipped onto the board
is fine for adjusting 3-1/2 and 4-1/2 digit DVMs and the AD584 only
benefits from two dangling 9V batteries with a 5-1/2 digit meter. Up
to 30V is permitted. At 27V the Fluke still reads +10.0021/22, but
lingers longer on 22.
-jsw

On Wednesday, May 17, 2017 at 7:24:32 PM UTC-4, Jim Wilkins wrote:
"Jim Wilkins" wrote in message
news
"Garrett Fulton" wrote in message
...
On Wednesday, May 10, 2017 at 6:40:09 PM UTC-4, Jim Wilkins wrote:
................
However my flea-market 1970's Fluke 4-1/2 and 5-1/2 digit bench
meters
are still within spec when measuring a 10V calibration standard.
-jsw

I've got 3 meters I'd like to check for calibration. Is that 10V
calibration standard something that costs an arm and a leg?

Garrett

https://www.amazon.com/DROK-Precisio.../dp/B00NL419KW
The reference IC is really an AD584.
Its hand-written label indicates that it measured 10.00222V on an
Agilent 34401A at 21C in 2015. My Fluke 8800A (no cal?) shows
10.0017/18, the Fluke 8600A (1995 cal) shows 10.002V.

-jsw

My house is now at 22C so as promised I rechecked theAD584 reference
against the 5-1/2 digit Fluke, after an hour warmup which decreased
the Fluke's initial 11 microVolt zero offset to +/-0.
Using an analog variable power supply, the Fluke reads +10.0018/19
with 12V powering the standard, and +10.0021/22 with 18V powering it.
It starts to droop below 10.0018 at less than 11.0V in.

I'd say that a more convenient 12V A23 battery clipped onto the board
is fine for adjusting 3-1/2 and 4-1/2 digit DVMs and the AD584 only
benefits from two dangling 9V batteries with a 5-1/2 digit meter. Up
to 30V is permitted. At 27V the Fluke still reads +10.0021/22, but
lingers longer on 22.
-jsw

I got one of these boards. Hooked it up just now to a bench supply at 15V. I checked one of my three Fluke 8840As that hadn't been calibrated in over 20 years. Holy crap dead nuts on target. Fluke builds some serious stuff.

And, for giggles, the Centech POS they were giving away at HF reads: 2.49, 4.99, 7.48, 9.98. Not nearly as bad as I expected.

Later, I'll check some more meters. But so far, I'm happy that I got the reference board, it confirms that my "reference" meter can still be trusted, and I needn't pay for calibration unless a particular job demands it.

On Saturday, May 6, 2017 at 10:09:36 AM UTC-4, rangerssuck wrote:
I have an unusual problem staring at me. I'm doing maintenance of an ice skating rink, and we have decided to replace the R22 with RS-45 as part of a general upgrade. The system was full of leaks and was constantly losing significant and costly amounts of R22.

This is a liquid overfeed system and as such, the refrigerant runs through the pipes under the ice surface. These pipes are buried in concrete and nobody knows how large they are. The people who installed this are long gone, and there is zero access to the piping after the large feed and return lines enter the concrete.

I need to determine how much refrigerant we need to buy. I have heard estimates ranging from 4000 pounds to 7000 pounds from various experts in the field. That extra 3000 pounds is almost $30,000, so it would be good to get a better feel for a real number. The refrigerant pipes in a typical rink are about 10 or 11 miles long (seriously), and are (sometimes) 5/8 OD thinwall steel, but that's a variable.

The R22 has been removed from the system - unfortunately, the quantity recovered really has no bearing on the actual capacity as there had been considerable leakage.

So, given that I have a system that's shut down and pumped out, and that I can isolate the rink floor pipes from the rest of the system and there are service valves accessible, does anyone know how I might determine the volume of these pipes?

I was thinking, perhaps, of filling with nitrogen at some regulated flow rate and watching for a pressure rise and then doing some magic calculations I haven't thought about since high school. Does that make sense? can anyone offer specifics?

I'd appreciate any help any of you can offer.

Thanks.

jpb

Crap - every time I try to get started on this, another emergency comes up. I did pump ump with air, and found a couple more leaks. Hopefully, this weekend I'll get to do the actual test.

"rangerssuck" wrote in message
...
On Wednesday, May 17, 2017 at 7:24:32 PM UTC-4, Jim Wilkins wrote:
...

And, for giggles, the Centech POS they were giving away at HF reads:
2.49, 4.99, 7.48, 9.98. Not nearly as bad as I expected.


All the yellow and red HF meters I have can be adjusted, though the
pot is overly sensitive.
-jsw

On Friday, May 19, 2017 at 12:38:38 PM UTC-4, Jim Wilkins wrote:
"rangerssuck" wrote in message
...
On Wednesday, May 17, 2017 at 7:24:32 PM UTC-4, Jim Wilkins wrote:
...

And, for giggles, the Centech POS they were giving away at HF reads:
2.49, 4.99, 7.48, 9.98. Not nearly as bad as I expected.


All the yellow and red HF meters I have can be adjusted, though the
pot is overly sensitive.
-jsw

Probably, but not really worth the trouble to get one more least significant digit. It's close enough to live in my glove compartment.

"rangerssuck" wrote in message
...
On Friday, May 19, 2017 at 12:38:38 PM UTC-4, Jim Wilkins wrote:
"rangerssuck" wrote in message
...
On Wednesday, May 17, 2017 at 7:24:32 PM UTC-4, Jim Wilkins
wrote:
...

And, for giggles, the Centech POS they were giving away at HF
reads:
2.49, 4.99, 7.48, 9.98. Not nearly as bad as I expected.


All the yellow and red HF meters I have can be adjusted, though the
pot is overly sensitive.
-jsw

Probably, but not really worth the trouble to get one more least
significant digit. It's close enough to live in my glove
compartment.

I use them for battery testing where the full range from charged to
discharged is 1V or less, on the 20V range, and the second decimal
place is reassurance that the first one is correct. Accidents do
happen so I wear safety glasses and don't risk my better meters.