Precision Pressure Measurement User Guide to Pressure Measurement P-CP-2010-0200 October 2016 Table of Contents Chapter 1—Fundamentals of Pressure Measurement 1.1 Gauge Versus Absolute Pressure ...........................................................................................4 1.2 Nominal Versus Actual Pressure..............................................................................................4 1.3 Units of Pressure Measurement ...............................................................................................4 1.4 Units of Mass Measurement ......................................................................................................5 1.5 Gravity ........................................................................................................................................ 5 1.6 Primary and Secondary Pressure Standards ..........................................................................5 Chapter 2—Deadweight Pressure Testers 2.1 Piston Gauge Type Deadweight Testers ..................................................................................6 2.1.1 Simple Piston & Cylinder ....................................................................................................6 2.1.2 Re-entrant Piston & Cylinder .............................................................................................6 2.1.3 Controlled Clearance Piston & Cyl. ...................................................................................7 2.2 Floating Ball Type Deadweight Testers ....................................................................................7 2.3 Other Types of Deadweight Testers ........................................................................................8 2.4 Intrinsic Pressure Correction Terms .........................................................................................8 2.4.1 Air Buoyancy .....................................................................................................................9 2.4.2 Thermal Expansion ............................................................................................................9 2.4.3 Surface Tension ................................................................................................................9 2.4.4 Tare Force .........................................................................................................................9 2.4.5 Area ................................................................................................................................... 9 2.4.6 Pressure Coefficient .........................................................................................................9 2.5 Site Location Correction Factors ............................................................................................10 2.5.1 Gravity ..............................................................................................................................1 0 2.5.2 Temperature ....................................................................................................................10 2.5.3 Test Level ........................................................................................................................11 2.6 Traceability and Uncertainty ....................................................................................................11 2.6.1 Traceability ......................................................................................................................11 2.6.2 Laboratory Uncertainty ...................................................................................................12 Chapter 3—Calibration of Deadweight Testers 3.1 Methods of Calibration .............................................................................................................13 3.1.1 Fundamental Characterization ........................................................................................13 3.1.2 Calibrated Characterization ............................................................................................13 3.2 Test Equipment for a Pressure Standards Lab ......................................................................13 3.2.1 Introduction ......................................................................................................................13 3.2.2 Hydraulic Piston & Cylinder Type Testers .....................................................................14 3.2.3 Pneumatic Floating Ball Type Testers ............................................................................15 3.3 Frequency of Calibration .........................................................................................................16 3.3.1 Piston & Cylinder Hydraulic Deadweight Testers ......................................................... 16 3.3.2 Floating Ball Pneumatic Deadweight Testers .................................................................16 Chapter 4—AMETEK Deadweight Testers 4.1 Deadweight Testers and Deadweight Gauges .....................................................................18 4.2 Features of AMETEK Hydraulic Deadweight Testers............................................................ 18 4.2.1 Model T & R Hydraulic Testers .......................................................................................20 4.2.2 Model 10 Hydraulic Testers ............................................................................................21 4.2.3 Model HL Hydraulic Testers ............................................................................................22 4.2.4 Dual Column Hydraulic Testers ......................................................................................22 4.3 Features of AMETEK Deadweight Gauges ............................................................................22 4.3.1 Model HLG Deadweight Gauge ......................................................................................23 4.4 Features of AMETEK Pneumatic Deadweight Testers .......................................................... 24 2 Table of Contents 4.4.1 Model PK II Pneumatic Tester .......................................................................................... 26 4.4.2 Model RK Pneumatic Deadweight Tester ....................................................................... 27 4.4.3 Model HK Pneumatic Deadweight Tester ....................................................................... 27 4.4.4 Model PK Medical Pneu. Deadweight Tester ................................................................. 28 4.5 Care of AMETEK Deadweight Testers ................................................................................... 28 4.5.1 Hydraulic Deadweight Testers ....................................................................................... 28 4.5.2 Floating Ball Pneumatic Testers ...................................................................................... 30 4.6 Procedures for the Use of AMETEK Testers ......................................................................... 31 4.6.1 Procedures for Cleaning Hydraulic Piston & Cylinder ................................................... 31 4.6.2 Procedures for Use of Hydraulic Deadweight Testers ................................................ 32 4.6.3 Procedures for Use of Hydraulic Deadweight Gauges ................................................ 33 4.6.4 Procedures for Use of Pneumatic Deadweight Testers ............................................... 34 Chapter 5—Manometers 5.0 Principle of Operation .............................................................................................................. 36 5.1 Types of Manometers .............................................................................................................. 36 5.1.1 U Tube Manometers......................................................................................................... 36 5.1.2 Inclined Tube Manometers .............................................................................................. 36 5.1.3 Well Type Manometers .................................................................................................... 37 5.2 Intrinsic Correction Factors ..................................................................................................... 37 5.2.1 Fluid Density Correction .................................................................................................. 37 5.2.2 Gravity Correction ........................................................................................................... 38 5.2.3 Pressure Medium Head Correction ................................................................................. 39 5.2.4 Scale Correction .............................................................................................................. 40 5.2.5 Compressability, Absorbed Gases and Capillary Considerations................................ 40 5.2.6 Parallax (Readability) ...................................................................................................... 41 Chapter 6—Secondary Comparison Pressure Standards 6.1 Types of Secondary Comparison Pressure Stds. ................................................................. 42 6.1.1 Mechanical Pressure Gauges ........................................................................................ 42 6.1.2 Electronic Pressure Gauges ........................................................................................... 42 6.2 Overall Application