Micron Guage, which is the best buy?

[itsiceman]

Ok so you would need special (calibrated) equipment and apparatus to get the "quick cal" done.

So I don't get how you would think this is a better hvacr micron gauge than a BluVac.

[Sapote]

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.

My bad. I was thinking the Pilot was BluVac and gave answers for BluVac.

I read the Pilot user manual again and it seems to use the default 760 mmHg for the atmosphere even though it says for the local atmosphere. So pilot has the same issue of local atmosphere calibration, but it pressure calibration range covers from 0 to 760,000 , better than just up to 25,000.

[itsiceman]

My bad. I was thinking the Pilot was BluVac and gave answers for BluVac.

I read the Pilot user manual again and it seems to use the default 760 mmHg for the atmosphere even though it says for the local atmosphere. So pilot has the same issue of local atmosphere calibration, but it pressure calibration range covers from 0 to 760,000 , better than just up to 25,000.

Full range with the app or onboard bar graph. Onboard graph has no numbers displayed over 25000 but it's the same data the app uses. Not enough room on the display but that range is only useful to see movement and not really a value. Wouldn't do a service tech much good knowing 500,000 from 600,000 other than knowing which way it's headed.export.pdf

[Sapote]

From their patent, it says the range was limited to 25,000 due to the data size of the 2nd order polynomial calibration.
I don’t see why it can display 25000 but not 990000.

[itsiceman]

From their patent, it says the range was limited to 25,000 due to the data size of the 2nd order polynomial calibration.
I don’t see why it can display 25000 but not 990000.

Extra digit would have to be smaller digits to fit the display. The analog bar graph shows the vacuum level from atmosphere to 25,000 where the bar graph resets to full.

The feature was added post original design.

It passes thru that range on a typical system pull down quickly. The pdf was the evacuation of a 30# recovery cylinder.
The plateaus up at the top of the graph was changing hoses and connections. Not sure what use the data is from 760,000 would be when it's essentially a straight line over a few seconds.

[Sapote]

Deleted

[bdserv]

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.

True. However, their application and derivation technique is atypical to a traditional WB application.

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?

I think the following from their patent may address that concern as well as any error from use at other than sea level.

"Additionally, the value PN may be analyzed during periods when the gas pressure within the vacuum sensor is known to be at atmospheric pressure, thereby determining whether or not a calibration sequence is required. If PN is not sufficiently close to a value of 1.000, i.e. different by 0.05% to 0.1% or greater, under the condition of atmospheric pressure, the vacuum gauge instrument may alert the operator that such a calibration is required..."

[Sapote]

I think the following from their patent may address that concern as well as any error from use at other than sea level.

Because it's an absolute pressure gauge, therefore the gauge should have the same error when being used at sea level or at other altitudes.
However, calibration at sea level vs. at other altitudes will make a difference in the value displayed (when used to measure vacuum).

"Additionally, the value PN may be analyzed during periods when the gas pressure within the vacuum sensor is known to be at atmospheric pressure, thereby determining whether or not a calibration sequence is required. If PN is not sufficiently close to a value of 1.000, i.e. different by 0.05% to 0.1% or greater, under the condition of atmospheric pressure, the vacuum gauge instrument may alert the operator that such a calibration is required..."

"the value PN may be analyzed during periods when the gas pressure within the vacuum sensor is known to be at atmospheric pressure, thereby determining whether or not a calibration sequence is required."

At atmosphere pressure? 760,000 at sea level or 654,000 at 4000' altitude? So if within 14% error the PN valve is acceptable? It's interesting to know how much deviation from 760,000 will cause it to request a calibration sequence.

[itsiceman]

Can anybody name any electronic hvacr vacuum gauge that even considers calibration at altitude.
The old testo may have but they don't make them like that anymore and had something like 500 micron resolution. Maybe the appion but what it looks like is a setting and not a calibration.

[itsiceman]

If not who cares.

[bdserv]

However, calibration at sea level vs. at other altitudes will make a difference in the value displayed (when used to measure vacuum).

I'm not convinced of that based on the stated shape of the sensor response curve.

At atmosphere pressure? 760,000 at sea level or 654,000 at 4000' altitude? So if within 14% error the PN valve is acceptable? It's interesting to know how much deviation from 760,000 will cause it to request a calibration sequence.

Get someone in Denver with a Bluvac that is still set to factory calibration to run the calibration test [it will "think" it is at the elevation it was originally calibrated at and if the PN value is off by more than 0.1% it will complain]. Or, borrow one and take a drive up into the CA high country and test it for yourself.

You could also just email Bluvac and ask them. They are very responsive.

[Sapote]

You could also just email Bluvac and ask them. They are very responsive.

I will ring them. Through my experience, most staff members don't understand what I am talking about, including sale and application engineers. Maybe the designer engineers understand the question.

[Sapote]

"Additionally, the value PN may be analyzed during periods when the gas pressure within the vacuum sensor is known to be at atmospheric pressure, thereby determining whether or not a calibration sequence is required. "

Here is what I don't understand of the above statement: at 4000', does it know the measured pressure value is 654000 or 760000? If the measured pressure is 65400 then why it doesn't trigger a calibration request?

[alexmmm]

Had my fair share of issues with the Testo. When I start to pull the vacuum all is good, but then I closed the valve to isolate the pump. Then turn it off.

Measurements of the hoses seemed fine between 550 & 551.

Problems start to happen though. The vacuum isn't stable when I close the T550 valve and it gets weaker.

[itsiceman]

Here is what I don't understand of the above statement: at 4000', does it know the measured pressure value is 654000 or 760000? If the measured pressure is 65400 then why it doesn't trigger a calibration request?

Probably because as you know these gauges don't measure pressure.

The vacuum gauge you designed was it a TC sensor?

If we knew what the response of the sensor was between 760,000 and 654,000 it probably doesn't match your theory.

Most likely no difference at all to this type of sensor.

They are cheap rugged sensors to be used by us knuckle dragging shaved apes in the field not some laboratory equipment.

[sspears000]

I am in HVAC/R school and the time has come for me to purchase a micron gauge. What is the best micron gauge? I have looked at Appion, BlueVac, Supco, Feildpeice, UEI, Elitech, etc. Which one is the best? And which one is the best value? Please help me with this issue. Thanks.

[sspears000]

I am in HVAC/R school and the time has come for me to purchase a micron gauge. What is the best micron gauge? I have looked at Appion, BlueVac, Supco, Feildpeice, UEI, Elitech, etc. Which one is the best? And which one is the best value? Please help me with this issue. Also, I am going to purchase the Appion Megaflow Basics Kit with the CRT tool. Do I need any other fittings.

[Gleng]

I first bought the Fieldpiece Vacuum Gauge.It is a good dependable gauge for about $135.00 I then bought the Blue Vac around $300.00.The blue Vac has more features.I would recommend the Fieldpiece for the money.The fieldpiece will do just fine, unless you have deep pockets .The Blue Vac is wireless though,if that is important to you.

[heatingman]

The micro bluVac is around 130 ish

Bare bones, but now has a wireless feature.

Sent from my SM-G930V using Tapatalk

[Flyin_Okie]

The micro bluVac is around 130 ish

Bare bones, but now has a wireless feature.

Sent from my SM-G930V using Tapatalk

I am curious where you found the micro at that price? I’ve not seen them under $200 at retailers.