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Digivac
DigiVac Bullseye Precision Vacuum Gauge
$556.43
In stockDigiVac Bullseye Precision Gauge, a portable thermocouple vacuum gauge with magnetic hands-free mounting and a 7 ft coiled sensor cable. Repeatable accuracy is plus/minus 2 millitorr or 20% from 1-99 millitorr, plus/minus 10% from 100-2000 millitorr and plus/minus 25% from 2-6 Torr, readable in twelve pressure units. Runs on 4 AA alkaline cells or Micro-B USB, with a field-replaceable sensor tube and a built-in leak/outgas/pump-down analysis.
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Description
The Bullseye Precision Gauge is a portable digital vacuum gauge built around thermocouple sensing, intended for field use rather than permanent installation. The instrument body carries a strong magnet for hands-free mounting and a protective rubber boot, and connects to its sensor through 7 ft of coiled cable terminated in an octal connector.
Display and analysis
Four display modes are available: numeric – in low-resolution, high-resolution or scientific-notation format – plus bar graph, line graph and pump-down graph. Readings can be shown in twelve pressure units: microns, millitorr, Torr, mm of Hg, mbar, bar, kPa, Pa, PSIA, inches of Hg, and mm and inches of water.
A Vacuum System Analysis runs continuously from the pump-down data set, recomputed roughly three times a second, and reports one of four states: PUMP (strong descent to vacuum), LEAK (pressure rising toward atmosphere faster than outgassing alone explains), OUTGAS (pressure rising at a decreasing rate) or STABLE. This is what makes the instrument useful for diagnosing a system rather than only reading it.
Accuracy
Repeatable instrument accuracy is quoted as plus/minus 2 millitorr or 20% from 1-99 millitorr, plus/minus 10% from 100-2000 millitorr, plus/minus 25% from 2-6 Torr, and continuous and monotonic from 6-760 Torr. With a replacement tube of the same type and manufacturer, and MID and VAC offsets reset to zero, accuracy is quoted as plus/minus 0.015 Torr from 0.001-0.099 Torr and plus/minus 30% of reading from 0.1-2 Torr and from 6-760 Torr.
The instrument is calibrated in nitrogen, whose thermal properties are close to air. Gases with higher thermal conductivity than air – water vapour, fluorocarbon refrigerants and acetone are the examples given – cause the gauge to read higher than actual pressure; gases with lower thermal conductivity, such as helium, oxygen and to a lesser extent CO2, cause it to read lower. Field calibration is supported at three points (5 millitorr, 1 Torr and 700 Torr) against a reference gauge you trust, and there is a built-in self-test that checks battery level and tube connection.
Specifications
Sensor: Thermocouple Plus SEN-VGT500, or Agilent 531/536, depending on configuration; field replaceable. Power: 4 AA alkaline cells or Micro-B USB. Front panel 6.0 in high x 3.5 in wide x 1.25 in deep. Ambient operating range -14 to 120 degrees F. Measurement media: clean dry air or nitrogen. Time to resolve: 2 seconds to the decade, 20 seconds to full accuracy. Over-range is indicated above 1000 Torr. The manual lists CE and RoHS for the controller display when used with the 536 sensor tube, and Bluetooth connectivity to a smartphone as an option.
Frequently asked questions
How accurate is the Bullseye Precision Gauge?+
Repeatable instrument accuracy is plus/minus 2 millitorr or 20% from 1-99 millitorr, plus/minus 10% from 100-2000 millitorr, plus/minus 25% from 2-6 Torr, and continuous and monotonic from 6-760 Torr. With a replacement tube of the same type and manufacturer, and MID and VAC offsets zeroed, the figures are plus/minus 0.015 Torr from 0.001-0.099 Torr and plus/minus 30% of reading from 0.1-2 Torr and 6-760 Torr.
Which gases can it measure, and how does gas composition affect the reading?+
Measurement media are clean dry air or nitrogen, and the gauge is calibrated in nitrogen. Because thermocouple sensing is thermal, gas composition matters: water vapour, fluorocarbon refrigerants and acetone have higher thermal conductivity than air and make the gauge read high, while helium, oxygen and to a lesser extent CO2 make it read low. If your process gas is not air or nitrogen, treat the reading as indicative.
What sensor does it use, and can it be replaced?+
A Thermocouple Plus vacuum sensor, part number SEN-VGT500, or an Agilent 531/536 sensor depending on configuration. The sensor is field replaceable, and the gauge has a good/bad tube indication plus a self-test that checks tube connection and battery level. Field calibration is supported at 5 millitorr, 1 Torr and 700 Torr against a reference gauge.
How is it powered, and what are the physical specifications?+
4 AA alkaline cells or Micro-B USB. The front panel measures 6.0 in high x 3.5 in wide x 1.25 in deep and the ambient operating range is -14 to 120 degrees F. The gauge attaches to its sensor through 7 ft of coiled cable with an octal connector and mounts hands-free with an integral magnet; a protective rubber boot is fitted.
What display modes and units are available?+
Numeric (low resolution, high resolution or scientific notation), bar graph, line graph and pump-down graph. Twelve pressure units are selectable: microns, millitorr, Torr, mm of Hg, mbar, bar, kPa, Pa, PSIA, inches of Hg, and mm and inches of water. Over-range is indicated above 1000 Torr.
What is the Vacuum System Analysis feature?+
The gauge continuously maintains a pump-down data set and, roughly three times a second, classifies the last quarter of it as PUMP, LEAK, OUTGAS or STABLE. That lets you distinguish a real leak from outgassing without a separate rate-of-rise calculation. The data set clears on power-off or when batteries are removed. Time to resolve is 2 seconds to the decade and 20 seconds to full accuracy.
