Micron Guage, which is the best buy?

[bdserv]

This maybe true for BluVac, but my Granville Phillips gauge has...

There is the root of the problem. You are giving us a lecture on how your Granville gauge works and haven't bothered to look into how the Bluvac is designed.

[Sapote]

There is the root of the problem. You are giving us a lecture on how your Granville gauge works and haven't bothered to look into how the Bluvac is designed.

No, I tried to explain how all micron gauges work in principle, including the calibration procedure, and using the Granville as an example.

I don't know what special design the BluVac has. Since you read their patent, what are the claims they made in the patent that different or improved from prior arts? I'm interested to know.

[Sapote]

There is the root of the problem. You are giving us a lecture on how your Granville gauge works and haven't bothered to look into how the Bluvac is designed.

I was explaining how all micron gauges work in calibration, and I believe it is correct. If you think otherwise then provide document as proof, and I'm interested to read.

[itsiceman]

The reason is that all micron gauges use a Wheatstone Bridge to measure the temperature lost caused by air density.

When you posted all micron gauges do you mean just all pirani micron gauges?

[bdserv]

The reason is that all micron gauges use a Wheatstone Bridge to measure the temperature lost caused by air density. The Bridge has 4 resistors and their values can drift with time, and so it needs to be balanced (calibrated) once in a while to be accurate.

I think the above statement is incorrect - all micron gauges [eg; the Bluvac] do not need to use a wheatstone bridge, which is normally used to measure very low resistances accurately.

The information is there for you to read if you are really interested, but I am not sure that you are.

[Sapote]

All micron gauges either use Wheatstone bridge or A/D converter to measure the heat lost by air density. Regardless which method of measurement, the analog characteristic of the thermistor and other components are drifting with time slowly, and so they need to be re-calibrate periodically to null out the drift.

[itsiceman]

Is this still about protecting my gauge with a isolation valve to prevent contamination?

I seriously don't remember the last time I've cleaned or calibrated either of my BluVacs and as of today they both show "GOOD" on the self check test.

They get used quite a bit. Never been isolated and I connect without a core in the side port of the core tool.

Most of the time I leave my micron gauge connected as I'm charging and checking operation.

I see no reason to add more tools and time plus maintenance for a problem that doesn't exist.

[GenesisRefrig]

Wow, this thread sure has morphed from glennac’s original question on which micron gauge to buy! We still use the analog gauge from Thermal Engineering. Just bought a replacement last year for one of them. They have been bulletproof and I’ve come to absolutely trust them. They look “old school”, but like I said, over 33 years using them, and they’ve never let me down.

[itsiceman]

Wow, this thread sure has morphed from glennac’s original question on which micron gauge to buy! We still use the analog gauge from Thermal Engineering. Just bought a replacement last year for one of them. They have been bulletproof and I’ve come to absolutely trust them. They look “old school”, but like I said, over 33 years using them, and they’ve never let me down.

Was my first vacuum gauge. It's another one that reads low stable readings if the weather matches a day in Hawaii and gives you those warm fuzzy feelings of evacuation accomplishment. Could get a couple real good gauges for the price of one of those. They don't even have the calibration procedure listed for that one anymore. It was two pages long.

[itsiceman]

I remember watching a bubbling sight glass and that one showing 400 microns

[itsiceman]

Of all the micron gauges marketed to hvacr I can only think of two that are of the pirani type.

[BALloyd]

Of all the micron gauges marketed to hvacr I can only think of two that are of the pirani type.

One is Inficon.....I have that one. What is the other?

Sent from my SM-G965W using Tapatalk

[itsiceman]

The one from navav

[itsiceman]

One is Inficon.....I have that one. What is the other?

Sent from my SM-G965W using Tapatalk

I was going to buy that one as my first gauge but got talked out of it. This was before bluvac.
Wondering now if reported weird readings was actually good reading just no one at the time had seen something different than the Thermal Engineering unit.
Everyone trusted the TE readings back then as a standard and anything that didn't follow was squirrelly or no good.
What's your feelings about the Inficon present day?

[Sapote]

Of all the micron gauges marketed to hvacr I can only think of two that are of the pirani type.

In BluVac Patent:
1. "The accuracy of a vacuum-sensing device may change through time, either through component value changes or through gradual contamination of the vacuum-sensing device. There is currently no method, save utilizing a second known-to-be-good gauge, for determining that a vacuum-sensing device, or its associated gauge instrument, is operating within its specified accuracy."

Not true. Granville gauge, an early design, already capable of calibrate against a known pressure as I can use a know pressure source or my local atmosphere.

2. "his creates a feedback loop that forces the voltage Vptv to have a value such that the ratios R1:Rtv and R3:R2 are equal, resulting in the following equation:
R tv=(R 1 ·R 2)/R 3"

This is the Wheatstone Bridge circuit equation even if the patent doesn't mention it.

3. "The power dissipated Ptv by the vacuum-sensing thermistor 130 is comprised of three components: (1) power conducted away from the thermistor by the surrounding gas molecules via convection and/or conduction; (2) power conducted away from the thermistor by the thermistor's own electrical connections; and (3) power radiated away from the thermistor's surface."

It might not mention in the patent, but this is exactly the definition of a Pirani vacuum gauge with a different type of resistor ( a thermistor instead of gold plated tungsten resistor). It used the exact Wheatstone bridge. The only difference is that it has a digital display that Pirani didn't have in 1906, with an A/D converter to convert the analog voltage into digital value for displaying, with Memory chip storing calibration parameter look up table.


I can't comment on the tool workmanship, but I think the Inficon gauge has better performance than BluVac in term of range and calibration (0 to 760,000 vs 0 to 25,000; calibrated to exact local atmosphere vs. constant 760 mmHg even at 4000' elevation), and its lower cost. The main claim of BluVac is its power saving method resulting in longer battery life.

Since BluVac can only display Hi for pressure above 25,000 microns -- it cannot display value at atmosphere -- how does one know if it is accurate or drifted with error? Have anyone used a known pressure jug to verify its accuracy?

[itsiceman]

Yes the battery lasts a long time but the big deal with a BluVac imo is it's precision and quick response in any ambient condition or changing conditions even. Real world field stuff.

If something comes close maybe there could be a real discussion of what it is best.

On the Pro and LTE versions the display bar graph shows progress above 25,000

Also the app displays full range from 760,000 to 0



Accuracy is only listed from 25,000 though but suspect the upper end is good enough for the girls we are dancing with.

[itsiceman]

In BluVac Patent:
1. "The accuracy of a vacuum-sensing device may change through time, either through component value changes or through gradual contamination of the vacuum-sensing device. There is currently no method, save utilizing a second known-to-be-good gauge, for determining that a vacuum-sensing device, or its associated gauge instrument, is operating within its specified accuracy."

Not true. Granville gauge, an early design, already capable of calibrate against a known pressure as I can use a know pressure source or my local atmosphere.

2. "his creates a feedback loop that forces the voltage Vptv to have a value such that the ratios R1:Rtv and R3:R2 are equal, resulting in the following equation:
R tv=(R 1 ·R 2)/R 3"

This is the Wheatstone Bridge circuit equation even if the patent doesn't mention it.

3. "The power dissipated Ptv by the vacuum-sensing thermistor 130 is comprised of three components: (1) power conducted away from the thermistor by the surrounding gas molecules via convection and/or conduction; (2) power conducted away from the thermistor by the thermistor's own electrical connections; and (3) power radiated away from the thermistor's surface."

It might not mention in the patent, but this is exactly the definition of a Pirani vacuum gauge with a different type of resistor ( a thermistor instead of gold plated tungsten resistor). It used the exact Wheatstone bridge. The only difference is that it has a digital display that Pirani didn't have in 1906, with an A/D converter to convert the analog voltage into digital value for displaying, with Memory chip storing calibration parameter look up table.


I can't comment on the tool workmanship, but I think the Inficon gauge has better performance than BluVac in term of range and calibration (0 to 760,000 vs 0 to 25,000; calibrated to exact local atmosphere vs. constant 760 mmHg even at 4000' elevation), and its lower cost. The main claim of BluVac is its power saving method resulting in longer battery life.

Since BluVac can only display Hi for pressure above 25,000 microns -- it cannot display value at atmosphere -- how does one know if it is accurate or drifted with error? Have anyone used a known pressure jug to verify its accuracy?

In regards to the pilot the cal button set the free air condition to 760,000

How does a tech in the field go about that at 4000 ft in some dudes backyard?

[Sapote]

In regards to the pilot the cal button set the free air condition to 760,000

How does a tech in the field go about that at 4000 ft in some dudes backyard?

He can't, and this is the error source in calculate the coefficients A, B, C which are needed in its real time calculation for the pressure under tested. And he cannot bring his refrigerator to the beach to calibrate the gauge from cold to warm temp changing.

[itsiceman]

He can't, and this is the error source in calculate the coefficients A, B, C which are needed in its real time calculation for the pressure under tested. And he cannot bring his refrigerator to the beach to calibrate the gauge from cold to warm temp changing.

Ok then how would a guy do it in his garage next his stocked beer fridge that doubles as a BluVac calibration device?

Trying to figure the edge you give to the pilot over BluVac since BluVac lists a ±5% yada yada and pilot lists a 10%± yadayada and operating temp to only 32°F

[Sapote]

It's tough to have 760 mmHg at his fridge unless he lives in Newport Beach. He can connect the gauge to a known 760 mmHg jug with a long hose, then chill the connected gauge in the fridge with the jug outside.