Model 2468
Ruska Pitot
Primary Standard

Technical DataFeatures• Automated primary standard for calibrating
pitot static test sets
• Pressure range: 0.4 to 103 inHg, optional
range from 3.4 to 400 inHg
• Accuracy to ± 0.5 feet, 0.003 knots• Ideal for calibrating RVSM compliant test sets
• Absolute and gauge calibrations for Ps, Pt
and Qc ranges• Calibrate in a variety of units including feet,meters, knots, inHg, mbar and several others

The Model 2468 Pitot Static Primary Standard
is specifically designed for calibrating today’shigh performance flight line and Air Data Test
Systems. With the new autofloat controller,operator intervention is reduced to simply applying the mass load indicated by WinPrompt®
software. WinPrompt applies all required correction factors, real time, to insure attainment of
the highest level of performance available in agas piston gauge which is required to calibrate
today’s RVSM compliant test sets. The Model
2468 is based on the popular Model 2465 Gas
Piston Gauge which has a long history of serving national standards laboratories, commercial
industry and government organizations as a
primary pressure standard for over 40 years.
Time-proven materials, hand craftsmanship,
and a lineage of intercomparisons to national
standards laboratories at the highest levels
are coupled with new automated technology
to make the Model 2468 Pitot Static PrimaryStandard the world’s choice for calibrating Air
Data Test Systems.

Automating the standard
The autofloat controller communicates through an
RS-232C interface with WinPrompt software, apowerful Windows based calibration management
program. WinPrompt automates all the functions
required to perform an accurate calibration withease. Since it is a Windows based application,
it can communicate through the Dynamic Data
Exchange (DDE) function with other Windows
applications such as a word processor to provide
customized calibration reports and spreadsheet
applications to perform graphical or numericalanalysis.
The process begins by creating a procedure
file with the sequence of altitude or airspeeds
required to calibrate a particular Pitot Static
Tester. Although these instruments typicallydisplay altitude in feet and airspeed in knots, theyusually require calibration in linear pressure units
such as in.Hg or mbar. WinPrompt allows theprocedure file to be setup in avionics units such as
feet, meters, knots or pressure units such as inHg,
mbar, kPa and many others. Once the procedurefile has been created and saved, it can berecalled whenever the particular test
set requires calibration, therefore minimizing
setup time.
For each point to be generated, WinPrompt
provides the operator with a list of masses (eachindividual mass is engraved with a uniquesequence number) to apply to the top of thepiston. The operator has the option of using trim
masses supplied to generate an exact value, oraccept the nominal value using only the main
mass set.
With the first point selected, the operator
uses the mouse to select the autofloat icon on
the menu bar. The software then prompts theuser to verify that the required masses havebeen applied. Upon confirmation by the user,
the autofloat controller generates the requestedpressure to the point where the piston is“floating”. Once the pressure is established,
the autofloat controller monitors all systemparameters and updates the actual generatedpressure, real-time. With a stable float position
obtained, the status bar at the bottom of thescreen changes from red to green indicating thatthe reading or adjustment of the device under
test can be made. The device under test reading can be entered along with any particularcomments in a separate text field. WinPrompt
records this information along with the actualpressure generated by the Model 2468. The
operator then proceeds through each step until
all pressure points in the procedure file havebeen generated.
Once the calibration procedure is complete,
the calibration file can be saved with a uniquefile name and a calibration report can beprinted. Since WinPrompt supports theWindows Dynamic Data Exchange (DDE)function of Windows, all information can beexported to a spreadsheet program to perform
mathematical and graphical functions and/or a word processing program for customized
calibration report documents.

Piston/cylinder assemblies
For calibrating most Pitot Static Test Sets,
only the standard piston/cylinder supplied isrequired. The standard piston/cylinder generates pressures from 1.4 to 103 inHg in autofloat
mode and from 0.4 to 103 inHg using a manualpressure adjuster. This provides an effective
altitude range from -610 to 19,812 meters

2 Fluke Calibration

Model 2468 Ruska Pitot Primary Standard(-2,000 to 65,000 feet) feet in autofloat mode
-610 to 27,432 meters (-2,000 to 90,000 feet)using a manual adjuster) and airspeeds over
1,000 knots. An optional piston/cylinder isavailable for generating pressures from 3.4 to
400 inHg allowing calibration of other pressure
related devices, such as pressure transducers.
Both the standard and optional piston/cylinder assemblies are manufactured fromproven materials that have evidenced superior
strength, durability, low distortion, low thermalcoefficients and virtually undetectable hysteresis over the last several decades, and have an
unparalleled record of long-term stability. Eachpiston/cylinder installs quickly into the pressure column without the need for special tools.
Piston/cylinder assembly change-out can becompleted in less than one minute.

Mass set
The Model 2468 is provided with a single mass
set that is used with either the standard or
optional piston/cylinder. Each mass is engravedwith a unique sequence number and a common
serial number. A storage case is supplied whichallows storage of the mass set and one or both
piston/cylinders. Each mass is machined to anominal value and is made from nonmagnetic
materials to provide long-term stability andeliminate sensitivity to magnetic fields. Forease of use, the entire mass set totals just
12 kilograms (26.40 pounds), with a maximum
platter mass of 1 kilogram (2.2 pounds). A laboratory grade trim mass set is included to allow
any pressure increment within the range andresolution of the piston/cylinder assembly.

Instrument base
The instrument base is designed with functionality, economy and space conservation in mind.
All electronic components are housed awayfrom the instrument base to eliminate errors
caused by thermal effects and magnetic fields.
The thermally isolated motor drive is connectedto the cylinder—eliminating pressure fluctuations and maximizing productivity. A durable,
acrylic bell jar is provided to allow absolute mode operation when calibrating
altitude and other absolutereference devices. A KF16 fitting is provided to simplify
installation and allow low
reference pressures.

The Model 2468 isused to calibrate test
sets like the Druck 405.

Vacuum pumps

Barometric reference

In order to operate over the entire altitude
and airspeed range, two vacuum pumps arerequired. One pump is connected to the reference port of the Model 2468 using a KF16
connection. This allows the area inside the bell
jar to be evacuated which is required for altitude
calibrations (absolute mode). A second vacuum
pump is connected to the autofloat controller
which allows automatic control of pressures
down to 1.4 inHg absolute. In order to generate
positive pressures, a regulated gas supply (cleandry air, or nitrogen) must be supplied to theautofloat controller. Ruska can supply vacuum
pumps which are rated to the appropriate
vacuum capacity and include an auto-vent valve
and backstream filter for contamination prevention along with a muffler for quiet operation.

The Model 2468 equipped with the autofloat
controller is provided with a barometric reference sensor to allow system operation inabsolute mode and also simulated absolutemode where establishing the bell jar vacuum(reference vacuum) is not required.

Connecting lines and fittings
Ruska can provide an optional lines and fittings
kit which includes all interconnecting tubing
for pressure and vacuum supplies along with all
required cables and adapters.

3 Fluke Calibration

Model 2468 Ruska Pitot Primary Standard

Computer
The autofloat system requires a standard
desktop or notebook computer for operation. A
Pentium level processor, RS-232 interface andWindows 95/98 are the only requirements. The
computer can be supplied by the customer orRuska can provide an optional notebook computer with the system which is pre-loaded with
Windows 95 or higher and WinPrompt software.

Manual configuration
Ruska also offers a manually operated pressure control system for setting the pressure andfloat position. This configuration can also be
used with WinPrompt software and the Model2456 Deadweight Gauge Monitor. The Model
2456 continuously monitors piston temperature,
float position, and sink rate, and optionally air
density and reference vacuum. WinPrompt calculates mass-to-pressure and pressure-to-massvalues, and when used with the Model 2456,
automatically reads and displays real-time
piston gauge parameters. A separate brochureis available that covers the Model 2456
Deadweight Gauge Monitor.

SpecificationsManual control packGeneral
Electrical power

115/230 V ac, 50/60 Hz, 15 W

Temperature

Operating temperature: 15 °C to 28 °C (59 °F to 82 °F)
Storage temperature: -20 °C to 70 °C (-4 °F to 158 °F)

Humidity

Operating humidity: 20 % to 75 % RH, non-condensing
Storage humidity: 0 % to 90 % RH, non-condensing

Pressure medium

High purity nitrogen or dry, clean air with less than 0.5 ppm hydrocarbon and less than 5 ppm H2O
content, dew point less than or equal to -50 °C (58 °F), and less than 50 micron particulate size.
Although lower quality gas can be used, the frequency of piston/cylinder cleaning will be increased.

Pressure range
Autofloat mode
standard piston/cylinder

Altitude: -610 m to 19,812 m (-2,000 ft to 65,000 ft)
Airspeed: 175 knots to 1,000 knots
Pressure: 1.4 inHg to 103 inHg (47 mbar to 3 500 mbar), gauge or absolute
Optional piston/cylinder
Pressure: 7.5 inHg to 400 inHg (255 mbar to 13.5 bar), gauge or absolute

Manual Mode
Standard Piston/Cylinder

Altitude: -610 m to 28,956 m (-2,000 ft to 95,000 ft)
Airspeed: 100 knots to 1,000 knots
Pressure: 0.4 inHg to 103 inHg (13.5 mbar to 3 500 mbar), gauge or absolute

For users who prefer a manually operated system, themanual control pack can beprovided with the Model
2468 instead of the autofloat
controller.
The manual control packincludes pressure and vacuum
inlet valves, precise pressure adjuster for fine pressure
control, reference gauge andvent valve.

Optional piston/cylinder
Pressure: 3.4 inHg to 400 inHg (115 mbar to 13.5 bar), gauge or absolute
Accuracy

Altitude

Accuracy

Airspeed

Accuracy

0 m (0 ft)

0.16 m (0.5 ft)

100 kts

0.003 kts

9,144 m (30,000 ft)

0.3 m (1.0 ft)

500 kts

0.003 kts

18,288 m (60,000 ft)

1.2 m (3.8 ft)

1000 kts

0.006 kts

Piston/cylinder assemblies
Standard piston/cylinderNominal area: 3.4 cm2 (0.52 in2)
Pressure range: 0.4 inHg to 103 inHg (13.5 mbar to 3500 mbar), gauge or absolute
Pressure accuracy: 0.0010 % RDG or 0.00003 inHg (0.001 mbar) (whichever is greater)
Pressure stability: 3 ppm per year
Materials: piston is 440C stainless steel, cylinder is cemented tungsten carbide
Thermal coefficient: 1.5E-05/°C

Optional piston/cylinder

Nominal area: 0.84 cm2 (0.13 in2)
Pressure range: 3.4 inHg to 400 inHg (115 mbar to 13.5 bar), gauge or absolute
Pressure accuracy: 0.0026 % RDG or 0.0008 inHg (0.028 mbar) (whichever is greater)
Pressure stability: 3 ppm per year
Materials: piston and cylinder are cemented tungsten carbide
Thermal coefficient: 9.1E-06/°C

Mass set
Total mass

12 kg (26.4 lb)

Max platter mass

1 kg (2.2 lb)

Includes trim mass set 1 mg to 20 g (0.0007 oz to 0.70 oz) and storage case
Autofloat system
Positive shut-off controller automatically generates pressure and maintains piston float position at desired pressure.
Float positiona

Inductive sensor
Float position resolution: 0.001 cm (0.001 in)
Sink rate resolution: 0.001 cm/min (0.001 in/min)

Pistontemperature

4-wire: 100 Ω PRT
Accuracy: ± 0.1 °C (± 32.18 °F)
Resolution: 0.01 °C (32.018 °F)

Air densitya

Sensor types
Temperature: thin film platinum 1000 Ω RTD
Humidity: capacitive IC humidity sensor
Barometric pressure: piezoresistive, monolithic
silicon pressure transducer

Accuracy
Temperature: ± 2 °C (36 °F)
Humidity: ± 15 %Pressure: ± 5 mmHg

Vacuumreferencea

Thermopile sensor
Accuracy: 10 % of reading or 10 mTorr (whichever is greater)
Resolution: 1 mTorr

Barometricreference sensor

Accuracy: better than ± 0.0008 inHg
Resolution: 0.0003 in.Hg

Computer interface
Requirements
aPentium level processor, RS-232C interface, monitor, mouse or other pointing device, keyboard; program
requires 2MB available hard disk space; Windows 95 or higherAlso applies to Model 2468 equipped with Model 2456 Deadweight Gauge Monitor. Additional information is provided inModel 2456 literature.

Expression of uncertainty conforms with the recommendations of the ISO Guide to Expression of Uncertainty in Measurement.

Fluke Calibration.	Precision, performance, confidence.™
Fluke Calibration
PO Box 9090, Everett, WA 98206 U.S.A.
Fluke Europe B.V.
PO Box 1186, 5602 BD
Eindhoven, The Netherlands
For more information call:In the U.S.A. (800) 443-5853 or
Fax (425) 446-5116
In Europe/M-East/Africa +31 (0) 40 2675 200 or
Fax +31 (0) 40 2675 222
In Canada (800)-36-FLUKE or
Fax (905) 890-6866
From other countries +1 (425) 446-5500 or
Fax +1 (425) 446-5116
Web access: http://www.fluke.com©2010 Fluke Calibration.
Specifications subject to change without notice.
Printed in U.S.A. 8/2010 3833666A D-EN-N

4 Fluke Calibration

Model 2468 Ruska Pitot Primary Standard

Modification of this document is not permitted
without written permission from Fluke Calibration.