Micron (vacuum) gauge

[JRLesan]

Recommendation for basic gauge???

[Recycled bullet]

Mityvac

[JRLesan]

mityvac appears to be an analog gauge hardly capable of reading in microns...

[CastingFool]

I can't remember the brand of the micron gauge I used at work, 15 yrs ago. I do remember sometimes it was difficult to really get that vacuum down, on some equipment. Pulling a vacuum on a recovery tank, due to short hose and few connections, 10 micron was easily obtained.

[15meter]

Are apples and oranges being mixed here?

Micron from my metrology days was a measure of length, as in .001 millimeter, or one millionth of a meter.

Measuring vacuum is a completely different animal, to the best of my knowledge.

But my dimensional metrology was almost exclusively in length measurement. Be it surface finish parameters, as in height of the "scratches" of a ground surface expressed in microns or micro inches. Or larger length, width or height dimensions expressed in millimeters or inches.

Never fooled with vacuum measurement. Is it expressed in the same units?

[chambers]

Use to use Thermal vac tool. Worked on many large systems with couple of pounds to 1000# charges. Was analog but never let us down.

[varmintpopper]

Micron, as in inches of mercury

Good Shooting

Lindy

Metrology = The science of measurement.

[.429&H110]

For door to door refrigeration work
Ritchie/ Yellowjacket makes a "micron" gage.

They are a tiny heater thermocouple 1/4 inch flare connection.
The idea is, a vacuum does not conduct heat
so as the thermocouple cools, the air must be going away.

Their weakness is that every system has oil in it and oil conducts heat.
A dirty micron gage is just silly.
I tied mine to a cap-tube drier, lasted much longer.
When my compound gage on my manifold pins down at 29 inches
that's just good advice. Might be a vacuum, might not.
For a Toyota, good enough.

Dehydrating a freon system is an art and a science
and takes time-money, ultralow freezers are critical,
cars, not so much, and cars leak anyway.
first step is 100 psi dry nitrogen pressure test
(never nasty wet compressed air or CO2!)
if you have a leak, you will never ever have a vacuum.
A few purges with dry nitrogen will get most of the moisture out.
Don't blow the oil out too.
The warmer a system is (100F is a good start)
the shorter the dehydration time.

One grain of water is a lot of water.

We banned R-22 for no good reason
and 22 would absorb water, dehydrate itself, to a point.
Non flammable, nontoxic, ran at 70 psi.
Mexico Saudi and China last year
made more R-22 than we ever did
for their "domestic" market.
The Senator from Dupont had 22 banned because the patent expired.

Now 134a is going away. 134a is actually toxic.
EPA said it wasn't, oh, well.
I'm glad Walmart has lots and lots still.
Stock up!

Have fun with R-1234yf!
It's flammable and toxic.
Now in cars near you.

Propane works fine as a refrigerant
cheap?
same numbers as R-22
and dehydration isn't a problem
because propane absorbs water
and carries oil just fine.

I'm glad I retired.
I can't say ozone hole without giggling.
The cows don't need sunglasses.

[06ackley]

I used the appion gauge

[wv109323]

What am I missing.? Convert the microns to psi and use a regular gauge.

[Newboy]

in the lab I use DigiVac gauge.


Sent from my iPhone using Tapatalk Pro

[fastdadio]

For door to door refrigeration work
Ritchie/ Yellowjacket makes a "micron" gage.

They are a tiny heater thermocouple 1/4 inch flare connection.
The idea is, a vacuum does not conduct heat
so as the thermocouple cools, the air must be going away.

Their weakness is that every system has oil in it and oil conducts heat.
A dirty micron gage is just silly.
I tied mine to a cap-tube drier, lasted much longer.
When my compound gage on my manifold pins down at 29 inches
that's just good advice. Might be a vacuum, might not.
For a Toyota, good enough.

Dehydrating a freon system is an art and a science
and takes time-money, ultralow freezers are critical,
cars, not so much, and cars leak anyway.
first step is 100 psi dry nitrogen pressure test
(never nasty wet compressed air or CO2!)
if you have a leak, you will never ever have a vacuum.
A few purges with dry nitrogen will get most of the moisture out.
Don't blow the oil out too.
The warmer a system is (100F is a good start)
the shorter the dehydration time.

One grain of water is a lot of water.

We banned R-22 for no good reason
and 22 would absorb water, dehydrate itself, to a point.
Non flammable, nontoxic, ran at 70 psi.
Mexico Saudi and China last year
made more R-22 than we ever did
for their "domestic" market.
The Senator from Dupont had 22 banned because the patent expired.

Now 134a is going away. 134a is actually toxic.
EPA said it wasn't, oh, well.
I'm glad Walmart has lots and lots still.
Stock up!

Have fun with R-1234yf!
It's flammable and toxic.
Now in cars near you.

Propane works fine as a refrigerant
cheap?
same numbers as R-22
and dehydration isn't a problem
because propane absorbs water
and carries oil just fine.

I'm glad I retired.
I can't say ozone hole without giggling.
The cows don't need sunglasses.

^^^ This folks, is the bottom line ^^^
Quick and to the point. I've been servicing HVACR equipment for over 35 years, and when it comes to vacuum, I can think of nothing more of value to add. Good post.
One other thing, I too will be retired soon. Next week will be my last week to work. Fri. 3/31 I'm going to drop my phone, pager, keys, credit card, and id badge on the boss's desk. My new job will be flinging lead and stretching the throttle cable on my motorcycle.

[15meter]

Micron, as in inches of mercury

Good Shooting

Lindy

Metrology = The science of measurement.

Interesting they use the same term and mix them in two different measuring units. I've only seen "micro inches" on the imperial side.

But the very little bit I did with vacuum was in inches of mercury, measured with a pretty crude analog "steam" gauge.

And my official title for a number of years during my days of gainful employment was "Metrology Product Specialist".

How's that for a mouth full?

Even an old retired dude can learn something new.

Now if I can only remember it tomorrow.

[BNE]

JRLesan,
What kind of equipment are you working on? AC or is it an ultra high vacuum furnace?

Work has used Agilent and Super Bee vacuum gages on our vacuum furnaces. The Super Bee has proven to be pretty robust.

[.429&H110]

I always wondered what the air pressure outside the ISS is.
ISS is in vacuum for sure
but hits enough air to slow it down, so there must be a number.
Probly micropascals, whatever those are.
Millionth of a millimeter of mercury, or so.
Thin as a democrats promise...

[.45Cole]

Ashcroft gauges for basic service are always good, you can probably find one to cover the stuff you're looking for. They are good and will last, you'll pay more than the china cheapies but you'll likely only have to pay once.

[.429&H110]

UAF has one of the last direct expansion hockey rinks.
That would be R-22 boiling in tubes under the ice
Two noisy 60 hp compressors.

One fine day we inspected the 1961AD receiver
so I drained push pull 5000 pounds pf R-22
into 300# recovery tanks
(fortunately was winter in Fairbanks)
(The 22 drained nicely into arctic cold tanks)
(I had a pallet scale that worked at -30 better than I did)

Pressure tested the rink and all with (a lot) of N2
For a wonder nothing leaked

Big Welsh vac pump got to 1000 microns in two days
(Welsh would do 5u deadheaded)
and 1000 microns held all afternoon, pump off.

Receiver was 1/2 inch thick, shiny on the inside,
changed out all the old valves, solenoids
added VFD starters, swapped out a compressor,
rewired the controls and alarms.

Took a day to pour in enough 22 to start a compressor.

No other gas would work in that system,
maybe ammonia or propane,
oil return was a problem even with 22
sometimes the oil would slug a little.

And UAF has enough 22 to replace one more charge.
I got some weary of handling 300# cans @495# each.

I like ice machines better, they're indoors.

[JRLesan]

Should have elaborated: residential A/C. Need to change evap coil and condensing unit and, as long as I'm going with new (410A) equipment, might as well get a decent micron gauge to use for evac analysis. In the past have always used manifold gauge but that's the problem with studying new methods...

[.429&H110]

Rule number zero:

Always silver solder with a nitrogen draft running through the copper.
If air hits the hot copper you make copper oxide:
sandpaper grit!

I use a run of cap tube to a regulator.
The trouble with heat pumps is that slag grit jams the reversingvalve.
There is no do-over.

Yellowjacket is the cheepest micron gage that works.

[.429&H110]

Rule number two:

Mike Rowe makes the point
"Safety is job two"

My millennial student worker would not wear safety glasses
until a hose blew off the recovery machine at 515 psi.
Just a whipping blur of oily refrigerant.

He impressed, not hurt. And put on his glasses.

R-410a recovers at over 500#, condenser pressure on a hot day.
and pushed a new yellowjacket hose off the barb.

Hose is rated 1000# until it gets hot.

I dunno why people resist safety glasses. Wear them.