The Model 2465 Gas Piston Gauge has a long history of serving national standards laboratories, commercial industry and government organizations as a primary pressure standard for over 40 years. Since its original introduction, enhancements have been made to increase performance and reduce operator workload. The autofloat controller configuration is a recent example of Fluke Calibration’s commitment to provide an easy to use, high performance, primary standard to the pressure calibration and metrology community. The Model 2465 provides the capability of generating pressures to within a total expanded uncertainty of 10 parts per million to 0.7 MPa and 26 parts per million to 7 MPa.
The Model 2465 is available in a variety of configurations to meet individual requirements. The three basic components of the Model 2465 are the Instrument Base, one or more Piston/Cylinder Assemblies, and a single Mass Set. The Autofloat Controller can be added to minimize operator workload and skill requirements, or select the Manual Pressure Control Pack. Last, decide which accessories and options will be required.
Instrument base
The instrument base is designed with functionality, economy and space conservation in mind. All electronic components are housed away from the instrument base to eliminate errors caused by thermal effects and magnetic fields. The thermally isolated motor drive is connected to the cylinder—eliminating pressure fluctuations and maximizing productivity. A durable, acrylic bell jar is provided to allow absolute and vacuum modes of operation. A KF16 fitting is provided to simplify installation and allow low reference pressures.
Piston/cylinder assemblies
Piston and cylinder assemblies are manufactured from proven materials that have evidenced superior strength, durability, low distortion, low thermal coefficients and virtually undetectable hysteresis over the last several decades, and have an unparalleled record of long-term stability. Tungsten carbide is used for all pistons and cylinders, except where the demand for accurate low pressures is met by using high quality stainless steel (low range piston). The lower density of steel facilitates generating pressures down to 1.4 kPa.
Four piston/cylinder combinations are now available to generate pressures over the total range of the system. The maximum sink rate for each piston/cylinder is 0.38 centimeters/minute. If lower sink rates are required, please refer to the Model 2468 Gas Piston Gauge.
Mass set
Each mass is machined to a nominal value and is made from non-magnetic materials to provide long-term stability and eliminate sensitivity to magnetic fields. For ease of use, the entire mass set totals just 6 kilograms, with a maximum platter mass of 1 kilogram. A laboratory grade trim mass set is included to allow any pressure increment within the range and resolution of the piston/cylinder assembly.
Manual pressure control
For manual operation, the Model 2465 can be provided with a manually operated Pressure Control Pack, instead of the autofloat controller, for regulating and controlling the system pressure and float position. The optional Model 2456 Piston Gauge Monitor and WinPrompt software add further capability to the manual system (see separate Model 2456 data sheet for additional information and specifications).
Operating modes
The Model 2465 is capable of operating in gauge, absolute and vacuum mode.
Gauge mode: pressure is achieved by simply loading the appropriate mass load to the top of the piston.
Absolute mode: A vacuum pump can be connected to the reference pressure port, using standard KF16 vacuum fittings. The appropriate mass load is applied and the bell jar is placed on the instrument base. The vacuum pump evacuates the bell jar and the residual amount of pressure is measured either automatically with the autofloat controller, (or with the Model 2456 Deadweight Gauge Monitor, in the manual configuration).
Vacuum mode: is achieved by generating a subatmospheric pressure with the Model 2465 and autofloat controller utilizing the internal, high accuracy, barometric reference sensor. The system subtracts the generated pressure from the barometric reference sensor and displays the result: a vacuum (negative gauge) pressure.
Low pressure mode: allows operation down to 0 gauge pressure, and is achieved by generating an absolute pressure at or above atmospheric pressure utilizing the barometric reference sensor in the autofloat configuration.

Accessories
Model 2456 Piston Gauge Monitor and WinPrompt software:
For users who do not require the autofloat capability, but want to add a level of automation to the Model 2465.
The Model 2456 continuously monitors piston temperature, float position, and sink rate, and optionally air density and reference vacuum. WinPrompt software calculates mass-topressure and pressure-to-mass values, and automatically reads and displays real-time piston gauge parameters.
Lines and fittings kits:
Lines and fittings kits are available to ensure that you have all the components needed to install the system and begin performing calibrations.
Vacuum pumps:
For applications where absolute or vacuum mode calibrations will be performed, two vacuum pumps are required. The autofloat configuration requires each pump to be equipped with an auto-vent valve so that the vacuum line is vented to atmosphere when the pump is turned off. Fluke Calibration can provide high quality vacuum pumps that meet these requirements. Fluke Calibration supplied pumps also include a backstream filter to prevent contamination of the Model 2465 and device under test along with a muffler for quiet operation.