An industrial OEM controls manufacturer required a fully automated End-of-Line flow test bench to calibrate and verify the operation of an electronically compensated fuel flow control valve. The valve was used to precisely control the flow rate of fuel to reciprocating gas engines. The test system was required to automatically manage the calibration and test sequence, requiring minimal intervention by the test operator.
- Flow Technology: Critical Flow Venturi (sonic nozzles) Based System
- Wide Service Range: Extended flow range with high accuracy and repeatability
- Multiple Communication Interfaces: To both the Unit Under Test and the flow stand
- Automated Data Management: For both test configuration input and test results to a corporate database
- Data Acquisition: Interfacing and Communication with a customer-supplied DAQ system
- Automated Testing Capability: Utilizing an off-the-shelf Test Executive
Flow Systems designed and manufactured an air flow metering test system that employed a binary set of ten sonic nozzles (also called “critical flow venturis” or “critical flow nozzles”). The two largest sonic nozzles were housed in piping runs that conform to ASME specifications. The smaller nozzles were housed in multiple nozzle manifolds, designed and manufactured by Flow Systems. The piping runs incorporated a pressure averaging piezometer ring with four pressure taps and a temperature tap, while the sonic nozzle manifolds contained multiple inlet pressure taps for pressure averaging.
The flow stand was composed of two separate carbon steel frameworks. One framework contained the sonic nozzle flow elements, while the second stand contained the shop air supply regulating valves and interface connections to the customer’s facility compressor pressurized header.
The test stand consisted of several integrated sub-systems that served to monitor and calibrate the product. The air handling sub-system was used to supply, regulate, and measure the flow rate of the test fluid (air) through the product. Various transducers were used to make the measurements required to calibrate and verify the operation of the Unit Under Test. The computer/data acquisition system was used to display the instrument readings and to stored data from the calibration and test parameters. The computer system also provided a continuous visual display of the system operation for validation and troubleshooting purposes. The database management portion of the system managed the handling of various records and files which the product requires, or which were generated from the calibration/test sequence.
The as-built test system was a joint effort between the OEM manufacturer and Flow Systems. Flow Systems designed and built the airflow test stand and developed a PC-base controller that incorporates the necessary Unit Under Test communication and automated test sequencing. The OEM manufacturer implemented a hardware/software solution for controlling the airflow test stand. This necessitated that the two controllers interface properly allowing for bi-directional communication.
- Flow Elements: Ten torodial throat design Sonic Nozzles with a binary progression of throat area
- Flow Element Calibration: ±0.35% of indicated discharge coefficient (traceability to NIST)
- Flow Element Inlet Pressure Calibration Range: 30 to 130 psia
- Flow Range: 7.5 to in excess of 15,000 lbm/hr of dry air
- Flow Stand Accuracy: Estimated at better than ±0.42% of reading
- Repeatability: 70 psi Estimated at better than ±0.1% (defined as two times the standard deviation divided by the mean of thirty identical samples)
This product is an example of a custom system developed and manufactured by Flow Systems. System hardware, controller software, fixtures, and facility requirements can all be configured to meet specific customer requirements. Custom test stands manufactured by Flow Systems are built using industry standard Commercial Off-The-Shelf (COTS) components utilize flow meters which are traceable to National Institute of Standards and Technology (NIST).
Photos & Schematics
The following are pictures and schematics of the Control Valve Test Stand.
System Physical Layout
View /Download Pneumatic and Instrumentation Diagram as PDF