Low Flow Air Test Stand from Flow Systems IncProduct Summary

The Low Flow Air Test Stand is an air flow measurement system specially designed for highly accurate and repeatable measurement at low flow ranges. It measures air flow for large aircraft and land-based, gas turbine parts, and meets a wide range of component flow range air testing needs of aerospace OEMs and their suppliers.

Key Features
  • Highly repeatable results (±0.15%)
  • Accurate measurement (±0.29%)
  • Wide range of part test pressures and mass flows
  • Highly customizable controller software for test automation and data management
  • Available in 1 and 4 port models
Related Products for Measuring Different Flow Ranges

The Low Flow Air Test Stand is one in a series of air flow test stands designed for the aerospace and turbine engine-based component industries. These test stands are designed to provide complete, automated solutions for flow measurement.

For information on related products, read the Air Flow Test Stand Product Comparison.

Complies with OEM Test Specifications

OEMs and their suppliers worldwide require quality airflow measurement of passages in both aircraft and land-based turbine engine components. Each OEM has a unique testing specification and their suppliers must be flexible with the test procedures in order to comply with each OEM test specification. Accuracy, repeatability, throughput and availability are critical elements in the design of these test systems. These air flow test systems currently comply with the in-house testing procedures of ABB/Alstom Power, ABB Gas Turbines, Pratt & Whitney America, Pratt & Whitney Canada, General Electric Aircraft Engines (General Electric Infra, Aviation), General Electric Power Systems (General Electric Infra, Energy), Honeywell, Mitsubishi Power Systems, Mitsubishi Heavy Industries, Allison Engine, Rolls-Royce, Solar Turbines, Siemens, Siemens-Westinghouse, Snecma, and many others.

Traceable to NIST

All Flow Systems air test stand sonic nozzles and instruments (P&T) are traceable to National Institute of Standards and Technology (NIST).

System Specifications

The Low Flow Air Test Stand is available in the following configurations:

Air Mass Flow Range Configuration Sonic Nozzle
Diameter Range
# of Sonic
Turndown Flow Port Connection Size & Type
0.0005 – 0.1 lbm/sec Standard 0.031″ – 0.177″ 6 200:1 (4X) 3/4″ (-12) Swagelok Full Flow Female Quick Connectors QF
0.0003 – 0.1 lbm/sec Option 1 0.022″ – 0.177″ 7 333:1 (4X) 3/4″ (-12) Swagelok Full Flow Female Quick Connectors QF
0.0005 – 0.22 lbm/sec Option 2 0.031″ – 0.250″ 7 440:1 (1X) 1″ (-16) Swagelok Full Flow Female Quick Connectors QF
0.001 – 0.22 lbm/sec Option 3 0.044″ – 0.250″ 6 200:1 (3X) 3/4″ (-12) Swagelok Full Flow Female Quick Connectors QF

Flow & Pressure Port Options

The test stand configurations listed above have two options for ports:

Model Name   # of Flow Ports
Configuration A   4
Configuration B   1

Additional Specifications

Specification Value(s)
Part Pressure Range 0.5 – 30 psig, custom ranges available
Part Pressure Ratio Range 1.04 – 3.0, custom ranges available
Accuracy ±0.29% of reading, NIST tranceable
Repeatability Less than ±0.15%, defined as 2 standard deviations divided by the mean of 20 samples
Pressure Connections 1/4″ (-4) Swagelok Full Flow Female Quick Connectors QF, color keyed
Cycle Time 30 – 60 seconds, capacity dependent
Dimensions 40” H x 50” W x 28” D
Weight 800 pounds

For additional information on system specifications, refer to the Test Stand Capabilities.

Uncertainty Analysis

Per TAE ISO Guide to Uncertainty in Measurement (GUM).  Contact Flow Systems for more detailed information.

Built with Commercial Off-The-Shelf (COTS) Components</>

All Flow Systems air flow test system designs, the test system controller, data acquisition and control subsystems, and all instrumentation are standard and readily available Commercial Off-The-Shelf (COTS) items. This ensures that service or replacement of any item can be achieved in a timely manner, providing for high availability of our products. When applicable, this includes all of the Unit Under Test related instrumentation specified by the customer.


National Instruments LabVIEW Logo
Control System Operator Interface

The system controller software handles the opening and closing of sonic nozzle flow paths, sets the proper pressure at the inlet of the Unit Under Test and calculates the mass flow through the sonic nozzle manifold. The controller also monitors the airflow conditions to ensure the sonic nozzles are in a “choked” state and that the flow is stable within ±0.1% of the pressure ratio set point. Controller software is written using National Instruments LabVIEW™.

Report Live Data and Compare to Historical Data
  • On-screen tabular and graphical results are displayed in real-time
  • Variety of user-customizable reports
  • Allows the operator to read all system sensors, read status and error messages
Schedule Single Test or Multiple Test in Series
  • Allows any number of configured tests to be executed in a sequence
  • Virtual tests can be programmed to calculate and evaluate results based on previous test values in algebraic equations
  • Programmable pause– operator can add a pause between tests for part modification or setup before starting the next test
Customize Controller Software and Integrate Data
  • Controller software can be customized to fit a wide variety of customer needs
  • Data can be integrated with customer’s local databases and/or information systems
Data Storage Formats
  • Standard storage format is SQL database
  • Customized data storage options available
Determines Test Measure Value Ranges of a Part
  • Allows the operator determine the “test measure” or flow value without knowing anything about the part other than the test setpoint
  • Used primarily for research and development to determine the test measures of a new or test part
  • Sets an upper and lower acceptance limit based upon the measured value and a user defined tolerance
Tests and Suggests Proportional-Integral-Derivative (PID) Parameters
  • The system flows the Unit Under Test and uses the natural response of the system to calculate Proportional-Integral-Derivative (PID) parameters
Monitor Performance using Statistical Process Control (SPC) – Optional for 1 Port Model
  • SPC features provide the customer a method for monitoring the performance of the Unit Under Test in real-time and in relation to previous production parts to identify variations in the part production process
  • Develop and manage flow test configurations in conjunction with shop floor controlling information system
  • SPC features can be customized to suit customer’s quality control criteria
Measure Static Pressure at a Single Hole (Pressure Probing)
  • Operator can measure the internal static pressure gradient in a part
  • Allows increased resolution for the operator to understand what the static pressure ratio is at a single hole in a part
Troubleshoot & Diagnose System and Part Leaks
  • Leak Test Diagnostics: Test the system and attached customer part fixtures for leaks
  • Critical Flow Venturi (CFV) Valve Leak Check Diagnostics: Determine the seal integrity of the CFV valves
  • Manifold Leak Test Diagnostics: Determine the leakage of internal test stand pressure manifolds to ensure integrity of test stand
  • Data Acquisition Device Diagnostics: Self-check to determine status and communication with data acquisition hardware and instrumentation
Test Fixture Flow Restrictions
  • Test the air flow restriction caused by the part fixturing
Troubleshoot Issues Using Internet-based Support – Optional
  • After connecting the test stand to the internet, receive technical support from Flow Systems
Facility Requirements

The facility requirements below are to be supplied by the customer at the installation site.

Electrical Power:   100 – 240 VAC / 50 – 60Hz / 1pH, 7.5 – 15Amp

Compressed Air Requirements

Inlet Air Connection:   3/4″ FNPT
Pressure Range:   70 – 120 psig
Temperature Range:   60° – 90°F
Particulates:   < 5 microns
Oil Content:   < 10 ppm
Pressure Dew Point: @ >100 psig:   < 39°F

Flow Rate: Equal to the lesser of the maximum capacity of the flow bench or the requirement of the largest part for a 100% duty cycle. An air receiver will allow for maximum flow at less than 100% duty cycle.

Photos & Schematics

Additional Software Screenshots

The following are pictures and schematics of the Low Flow Air Test Stand.

Low Flow Air Test Stand

System Schematic

System Schematic


The following is a list of options available for this test stand:

  • Software customization including database integration, networking, SPC (Statistical Process Control) and more
  • Custom Fixturing Options
  • Compressors, dryers, filters and receivers
  • On-site installation, training, commissioning and upgrades
  • Heat exchangers and Dewpoint alarm
  • Silencers

System Check Standards

The following optional additions are available to monitor the ongoing system accuracy and can also be used to diagnose problems: