{"id":744,"date":"2026-06-15T10:09:51","date_gmt":"2026-06-15T04:39:51","guid":{"rendered":"https:\/\/neometrixgroup.com\/resources\/?p=744"},"modified":"2026-06-15T11:20:12","modified_gmt":"2026-06-15T05:50:12","slug":"cv-control-valve-test-rig-guide","status":"publish","type":"post","link":"https:\/\/neometrixgroup.com\/resources\/cv-control-valve-test-rig-guide\/","title":{"rendered":"CV & Control Valve Test Rigs: The Complete Guide to Flow Coefficient Testing"},"content":{"rendered":"

Control valves regulate flow in industrial pipelines, process plants, aircraft fuel systems, and defence hydraulic circuits. Before any control valve enters service \u2014 whether it’s controlling steam in a power plant, fuel in an aircraft engine, or coolant in a defence vehicle \u2014 it must be tested to verify its flow coefficient (Cv or Kv), pressure drop characteristics, and leakage performance under rated conditions.<\/p>\n

A CV and control valve test rig is the precision instrument that performs this verification \u2014 measuring exactly how much fluid passes through a valve at a given pressure differential, across the full range of valve positions from fully closed to fully open.<\/strong><\/p>\n

\"Neometrix<\/h2>\n

What is a Flow Coefficient (Cv\/Kv)?<\/h2>\n

The flow coefficient is the single most important performance parameter of any control valve. It quantifies how much fluid the valve passes under standardised conditions.<\/p>\n

Cv (US customary):<\/strong> The number of US gallons per minute of water at 60\u00b0F that flows through the valve with a 1 psi pressure drop. Defined by ISA 75.01 and ANSI\/FCI 70-2.<\/p>\n

Kv (SI\/metric):<\/strong> The number of cubic metres per hour of water at 5\u201340\u00b0C that flows through the valve with a 1 bar pressure drop. Defined by IEC 60534-1.<\/p>\n

Conversion: Kv = 0.865 \u00d7 Cv<\/p>\n

The Cv\/Kv value at full open determines the valve’s maximum flow capacity. The Cv\/Kv curve across valve travel determines the valve’s control characteristic \u2014 equal percentage, linear, or quick-opening.<\/p>\n

Why Control Valve Testing Matters<\/h2>\n

Process industries:<\/strong> A control valve with incorrect Cv installed in a process loop causes poor process control \u2014 either starving the process of flow or flooding it. In oil and gas, chemical, and power generation applications, this directly impacts production efficiency and safety.<\/p>\n

Aerospace and defence:<\/strong> Fuel control valves, hydraulic selector valves, and environmental control system valves in aircraft and defence systems must meet strict Cv specifications. A valve that flows 10% more than specified can destabilise a fuel control loop; one that flows 10% less may starve an actuator.<\/p>\n

Procurement and certification:<\/strong> International standards (ISA, IEC, ANSI) require that control valve manufacturers provide certified Cv\/Kv data with every valve shipment. This data must come from a calibrated, traceable test rig.<\/p>\n

What a CV Test Rig Measures<\/h2>\n

Flow coefficient (Cv\/Kv):<\/strong> At each valve position, the test rig measures flow rate and pressure differential simultaneously. Cv = Q \u00d7 \u221a(SG\/\u0394P) where Q is flow rate, SG is specific gravity, and \u0394P is pressure drop.<\/p>\n

Pressure drop vs flow:<\/strong> The full \u0394P-Q curve across the valve’s operating range.<\/p>\n

Valve characteristic curve:<\/strong> Cv plotted against valve travel \u2014 verifying equal percentage, linear, or quick-opening characteristic as specified.<\/p>\n

Seat leakage:<\/strong> With the valve fully closed, leakage flow at rated shut-off pressure \u2014 tested per ANSI\/FCI 70-2 leakage classes (I through VI).<\/p>\n

Flow capacity:<\/strong> Maximum flow rate at rated pressure differential across the valve.<\/p>\n

International Standards<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n\n
Standard<\/th>\nRegion<\/th>\nScope<\/th>\n<\/tr>\n<\/thead>\n
ISA 75.01<\/td>\nUSA\/International<\/td>\nFlow equations for control valves<\/td>\n<\/tr>\n
ISA 75.02<\/td>\nUSA\/International<\/td>\nControl valve capacity test procedure<\/td>\n<\/tr>\n
IEC 60534-1<\/td>\nInternational<\/td>\nControl valves \u2014 terminology and general considerations<\/td>\n<\/tr>\n
IEC 60534-2-1<\/td>\nInternational<\/td>\nFlow capacity \u2014 sizing equations<\/td>\n<\/tr>\n
ANSI\/FCI 70-2<\/td>\nUSA\/International<\/td>\nControl valve seat leakage classification<\/td>\n<\/tr>\n
ASME B16.104<\/td>\nUSA<\/td>\nControl valve seat leakage<\/td>\n<\/tr>\n
EN 1267<\/td>\nEurope<\/td>\nIndustrial valves \u2014 flow resistance testing<\/td>\n<\/tr>\n
API 598<\/td>\nUSA\/International<\/td>\nValve inspection and testing<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Applications by Industry<\/h2>\n

Oil & Gas:<\/strong> Process control valves on wellheads, separators, pipelines, and refineries \u2014 tested per ISA 75.02 and API 598 before installation.<\/p>\n

Power Generation:<\/strong> Steam control valves in turbines, feedwater control valves, and pressure reducing stations \u2014 Cv certification required by plant design engineers.<\/p>\n

Aerospace Fuel Systems:<\/strong> Fuel metering valves, engine fuel control valves, and cross-feed valves \u2014 tested to aircraft OEM specifications and MIL-V-25675 for military aircraft.<\/p>\n

Defence Hydraulics:<\/strong> Directional control valves, proportional valves, and selector valves in armoured vehicles, naval vessels, and ground support equipment.<\/p>\n

Chemical & Pharmaceutical:<\/strong> Process control valves in reactor feed systems, distillation columns, and batch processes \u2014 ANSI\/FCI 70-2 leakage class documentation required for GMP compliance.<\/p>\n

Water & Wastewater:<\/strong> Flow control valves in treatment plants and distribution systems \u2014 tested per EN 1267 for European installations.<\/p>\n

Neometrix CV and Control Valve Test Rig<\/h2>\n

The Neometrix CV and Control Valve Test Rig is a precision flow testing system for industrial and aerospace control valve Cv\/Kv characterisation, pressure drop measurement, and seat leakage testing.<\/p>\n

Key specifications:<\/strong><\/p>\n