VIM-2®
First stationary and mobile
Spinning Rotor Gauge with
Li Ion TechnologyKey Advantages• True stationary and mobile
Spinning Rotor Gauge(>2 h battery life time)• 10 mbar to 5 x 10 mbar
measuring range-7• Safe, all metal, ambienttemperature• Cost-effective two-part design• Plug and measure, incl. App &Bluetooth (optional)• Internal and external data logger• High intrinsic accuracy andneglectable drift over time

RS 48524 VDC

Introduction
The VIM-2 is a stationary (grid operation) and mobile, battery-operated,highly accurate and long-term stable vacuum pressure gauge based on
Spinning Rotor Gauge (SRG) technology.
Spinning Rotor Gauges are characterized, among other things, by theoption to separate the sensor and measuring head / electronics and thus
enable checking static vacuums in a very cost-effective manner. Due toits simplicity, the all-metal sensor can be permanently welded to thevacuum system and delivers reliable measured values even after years ofuse. Only the ball in the tube, and no electronic components, remain on
the chamber to be measured. The system is uniquely resistant tomechanical stress and non-chlorinated corrosive media. Any interaction
with the vacuum chamber takes place via electromagnetic forces that lift
and accelerate the ball and measure its braking behavior. Corresponding
mechanical protection that needs to be attached from the outside isincluded.

Advantages – Portability, accuracy and long-term
stability
Applications:• All thermal vacuum insulation
applications• All conductive vacuum
insulation applications• Documentation, QC, R&D,
Preventive Maintenance• Trouble shooting and safety
check without opening thevacuum chamber

info@ph-instruments.euSpinning Rotor Gauges were previously considered to be complex tooperate and were therefore almost exclusively used in calibrationlaboratories. A main application was, for example, the calibration of highvacuum measuring devices, ionization gauges.
The VIM-2, as a grid and battery-operated device, is user-friendly, works
largely independently and can be run remotely (App via Bluetooth(optional)). It is for instance particularly suitable for measurements oncryogenic, vacuum-insulated liquid gas tanks. It´s a safe option as it does
not require any electrical feedthroughs, making it an all-metal sensor thatis extremely robust and resistant to aging. Compared e.g. to the Piranibased measuring method, the measuring range is extended by approx. 3
decades into the high vacuum region, and thus provides greater and far
more valuable information. It is a direct, mathematical / physical method,that only uses the effect of decelerating a rotating ball as it collides withthe gas molecules as a measure of pressure.

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Most other methods use ionization by means of hot filaments or high voltage to indirectly measure
the pressure, they are mechanically less stable and sensitive to contamination, even impact thevacuum pressure measurement themselves (by degassing/ionization and sputtering). Heat transfer
methods (Pirani) have a limited measurement range below 10 -3 mbar (w/o zeroing, which is often
impossible). In general, all other UHV measurement methods have electrical feedthroughs andfragile electronic components in the vacuum part.
SRGs on the other hand have a unique high level of accuracy, long-term stability, no feedthroughs,
measure with a simple sphere at ambient temperature, in a simple tube, all interaction with thevacuum is through electromagnetic forces.
The power supply-independent VIM-2 gives total mobility for large and remote measurement
locations, it runs for hours before recharge.
Despite of SRGs of the past, a reliable measurement is provided due to the strong magnetic fields
and high rotation frequency of the sensor. VIM-2 generates a magnetic field that is twice as strong(90 mT) as previously available SRGs. The standard rotation frequency of the sphere at 615 Hzprovides a much more stable suspension in the magnetic field. Both effects result in an improved
tolerance to imperfect alignment of the sensor tube on e.g. the cryo vacuum tank and more reliably
capturing the sensor ball.
The measuring heads are not sensor-specific and therefore interchangeable with one another, andpreviously installed sensors, so each head can measure a large number of sensors without asignificant loss of accuracy.

Measurement principle
The Spinning Rotor Gauge is based on the effect that gas molecules slow down a moving body as
they are adsorbed on its surface and then re-emitted. The statistically distributed molecules striking
from all directions are accelerated accordingly and brake the body (momentum transfer, arearelated particle flux density).
In the low pressure regime (< 1 x 10 -7 mbar) the desorption of the accelerated gas molecules does
not contribute to the rotation frequency. At pressures above 1 x 10-4 mbar and mean free paths in
the cm range, the gas viscosity is automatically compensated by means of an integrated
temperature measurement.
In the case of the SRG, a simple precision ball is used as the sensor and the deceleration isdetermined by inductive measurement in the sensor head. Factors such as the molecular massand temperature changes are only included in the measurement in an easily determinable root
ratio.
Additionally, within small limits, variable factors determine the braking of the rotating ball:
1. The “residual drag” results from the material properties of the ball. It is particularly relevant for< 10-5 mbar and can be roughly pre-determined and stored as required.
2. The "molecular drag" is the actual deceleration by the surrounding medium and proportional tothe pressure. The molecular drag contains the calibration factor, which deviates from a ideallysmooth sphere (factor 1) by max. ± 6 % without any calibration, ± 1% can be achieved.
It should be noted that even without setting the calibration factor or the zero point, and even afteryears, the system still has a unique intrinsic accuracy in high vacuum, which cannot be achievedby any other vacuum measurement method and is more than sufficient for many applications.

Measurement range
Due to their principle, Spinning Rotor Gauges can be used in pressure ranges from atmosphere toUHV. Due to geometric and electromechanical conditions, however, they are optimized for thepressure range, in which they achieve uniquely high levels of accuracy and long-term stability:
1% accuracy of the measured value between 0.1 and 1 x 10-6 mbar can be achieved if needed,<1% drift per year is typically. The measuring range in general is 10 mbar to 5 x 10-7 mbar.

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Technical Data
Measurement Principle
Measurement Range
Achievable accuracy
Measurement timeLong term stability
Wetted materials
Alignment
Analog interfaces
Digital interfaces
Internal data logger
Remote control / GUI
Operating TemperaturePower requirements
Analog output
Flange Type
WeightDimensions
Power supply
Power consumption
Run time in battery mode
Battery charging time

Spinning Rotor Gauge
7 Torr to 4 x 10-7 Torr / 10 mbar to 5 x 10-7 mbar
7 Torr to 0.07 Torr / 10 mbar to 0.1 mbar ca. 10 % of reading
0.07 to 7 x 10-7 Torr / 0.1 to 1 x 10-6 mbar 1 % of reading3, 5, 10, 20, 30 s
< 1 % drift each year
1.4404, 1.4034
Horizontal
USB Type C, Bluetooth (optional), High Density 15-polig
USB, Bluetooth (optional), RS 232 (service), RS 485
1023 values
Win7/10Electronics 10 °C to 40 °C (50 F to 104 F)
Measurement head 10 °C to 50 °C (50 F to 122 F)
Sensor tube bakeable until
150 °C (302F) elastomer sealed
450 °C (842F) metal sealed
18 to 28 VDC
0 bis 10 VDC configurable
KF 25, CF40, 8 VCR, welding socket
Device 1650 g (58 oz), power adapter 510 g (18 oz), head 750g (26.5 oz)
L x B x H = 325 x 275 x 100 mm (13 x 11 x 4 in.)
Grid or battery operation
Maximum 1.5 A at 24 VDC, typically < 1 A>2hIn 4.5 h to more than 95% of current capacity

About usph-instruments develops, manufactures and sells vacuum measurement systems with unique technologies
for demanding tasks in industry, research and science. Our guideline is to provide our customers with costeffective and application-related solutions. Our specialists each have more than 20 years of experience inmeasuring and regulating pressures in the vacuum sector. The products are developed and produced inGermany and Austria and meet the highest quality standards for measuring accuracy, sustainability andreliability. Innovative technologies help to increase energy efficiency and thus protect the environment from
unnecessary CO2 emissions.

Specifications can be changed without further notice.

info@ph-instruments.eu

www.ph-instruments.eu+43 720 500217