2485 Hydraulic Piston Gauge

The Model 2485 hydraulic piston gauge is a high precision standard that provides unsurpassed performance in the field of hydraulic piston pressure gauge metrology. The Model 2485 continues the Fluke Calibration standard of excellence, building on over 50 years of piston gauge manufacturing expertise. This instrument can be used to calibrate virtually any pressure device including other industrial or portable piston gauges, transducers, transmitters, gauges, or pressure switches. Available in dioctyl sebacate (DOS) oil, the Model 2485 can also be used in multiple media systems to facilitate calibrations of the wide variety of instrumentation in use today.

Each Model 2485 system includes a calibration report traceable to the U.S. National Institute of Standards and Technology (NIST). Traceability to other national or international standards organizations is also available.

The Model 2485 is designed for easy use and for the space limitations of today’s calibration environment. The entire benchtop system requires less than two square feet of bench space. The main pressure housing secures the piston/ cylinder assembly and provides support for the mass load. Two adjustable support legs and a permanently attached, sensitive level indicator facilitate precise alignment of the piston axis. A fixed support leg directly underneath the main pressure housing supports the load and eliminates platform distortion so that continuous level adjustments are not needed. An auxiliary pressure housing, fluid reservoir, valves and positive displacement pump are enclosed by a simple cover that is easily removed for servicing internal components. The auxiliary housing also provides a convenient location to connect a device under test. A rapid fill pump is used to quickly purge hydraulic lines of air prior to starting the calibration procedure.

 Other design features include a valve for connecting to an external reservoir (useful for applications where a reservoir larger than 250 mL (8.5 oz) is needed), and a liquid-inglass thermometer to aid in compensating for temperature effects. Reservoir and system isolation valves allow for pump recharging when returning the system to atmosphere. The drive motor can be used to provide consistent relative motion between the piston and cylinder when the inertia of a small mass load is insufficient to maintain adequate free rotation time.

The mass set for the Model 2485 includes:

Each mass is adjusted to within 50 ppm of the nominal mass denomination and calibrated to 5 ppm. Each mass is marked with the serial number of the set, a sequence number and the nominal mass denomination. The mass set is supplemented with a laboratory-style trim mass set, with denominations to 5 mg (0.0002 oz), to generate any pressure within the range and resolution of the instrument.

The Model 2485 piston/cylinder assemblies are simple in configuration and there are no mounting flanges or other geometric irregularities that can result in complicated stresses in the cylinder. This design minimizes stress due to mounting and sealing, and allows quick and easy changeout of all ranges without special tools.

The effective area of each Model 2485 piston/ cylinder assembly is adjusted so that a given load in kilogram denominations will generate nominal pressure increments in either English (psi) or SI units (bar). All assemblies are identified with a pressure unit/increment designator and serial number.

All piston/cylinder assemblies are manufactured from cemented tungsten carbide, offering superior strength and proven durability for:

The manufacturing techniques used for the Model 2485 piston/cylinder assemblies ensure undetectable pressure change due to speed or direction of rotation, resolution better than 1 ppm, a sink rate typically less than 0.25 mm (0.01 in) per minute at maximum pressure and a useable pressure range down to 1 % of full scale (FS).

The Model 2485 features the PistonSafe system, a unique non-rigid system that results in automatic centering of the mass load and protection of the piston/cylinder assembly from forces induced by loading and unloading masses. The system minimizes lateral forces, maintains the vertical force along the piston axis, reduces friction, and promotes a higher level of performance than with rigidly mounted load. The piston and cylinder components are fully protected should the pressure be released while under load, or the load removed while at full pressure. Installation or change of piston/cylinder ranges is quick and easy and can be completed in minutes without special tools.

For more consistent calibrations, use Model 2456 deadweight gauge monitor and WinPrompt® calibration software.