P3000 Pneumatic Deadweight Testers

P3000 Series Vacuum and Dual Vacuum/Pressure Models 
The combined vacuum/pressure models are extremely versatile instruments providing vacuum through 500 psi (35 bar) capacity in one unit. For added expansion, an additional low range piston/weight set can be provided for pressures to 800 inH2O (2 000 mbar). An optional built-in hand pump can be installed to generate vacuum (90%) through 300 psi. 

P3000 Series Liquid Lubricated Gas Operated Models 
The Models P3031 and P3032 feature an oil lubricated piston/cylinder assembly, which ensures that the instrument is less susceptible to performance issues caused by contamination of the gas supply or the environment in which the unit is being operated. 

The supply gas, via the deadweight tester controls, is introduced into the piston/cylinder chamber. As the gas acts directly on the surface of the oil, there is a rate-less transfer of pressure within the system. 

The instrument is designed to prevent inadvertent over-filling of the chamber, thus avoiding contamination of the gas system. There is no physical barrier between the gas and oil so there is some “oil-mist” transfer potential. Therefore, we do not recommend the standard version for oxygen service. A special version of these instruments using an oxygen compatible fluid is available.   

Operating principle 
Deadweight testers are the high performance pressure standards for pressure measurements. Utilizing the well proven piston-gauge system consisting of a vertically mounted, precision lapped piston and cylinder assembly, accurately calibrated weight masses (Force) are loaded on the piston (Area), which rises freely within its cylinder. These weights balance the upward force created by the pressure within the system. The pressure is measured when placed on a correctly spinning and floating piston. The total pressure measured is the summation of the weights plus the piston weight carrier assembly. 

Instrument base 
There are four basic variations in the pneumatic offering; single pressure, single vacuum, dual vacuum and pressure, and oil-lubricated pneumatically driven high-pressure models. Pressure or vacuum is generated by an external source or an optional built-in hand pump. The hand pump option is not available on instruments above 500 psi (35 bar). 

Piston/cylinder assemblies 
The piston/cylinder assembly is the heart of each deadweight tester. They are manufactured from materials that provide stability, durability, and low thermal coefficients and distortion. Our experience and knowledge of piston/cylinder production and calibration ensure the precision and performance required for today’s demanding calibration requirements. 

Weight masses 
Standard weight masses are series 3 nonmagnetic austenitic stainless steel. Each mass is marked with the serial number of the instrument  and the nominal pressure value relative to the high- or low-pressure piston, when applicable. Vacuum weights and the optional fractional weights are stainless steel and/or solution heat treated aluminum. 

Gravity correction 
Gravity varies significantly with geographical location and this variation has a direct effect on the force of the weights and the accuracy of the deadweight tester. Each instrument can be calibrated to local gravity at no extra cost. If unspecified, instruments will be calibrated to Standard Gravity at 980.665 cm/s2. 

Gas supply 
All instruments are fitted with a ⁄ NPT female external supply port for connection to the gas supply source. A compressed gas bottle (nitrogen or dry air) fitted with a pressure regulator is recommended. Ten percent above the maximum pressure is required. A built-in hand pump is available on some models to generate pressures to 300 psi (20 bar). For vacuum requirements, an external vacuum pump can be connected to the ⁄ NPT port. The built-in hand pump will also generate up to 90 % vacuum.