Jet Fuel Filter Test Stands
The Testand Jet Fuel Filer Test Stand performs dirt capacity testing of aircraft fuel filter elements per SAE procedure ARP1827B. The fully automated system provides precisely controlled test conditions for accuracy, repeatability and operator safety.
SAE Aerospace document ARP1827B (Revised 2009-10) prescribes the testing apparatus and test procedures for evaluating the dirt capacity and element efficiency for jet fuel non-cleanable (disposable) fine fuel filter elements used in aviation gas turbine engine fuel systems.
The nominal flow capacity for the test stand is 20 to 150 gpm. Other flow ranges are available. The maximum recirculated flow rate is 80% of the total flow. The maximum test article differential pressure is 125 psid. Military Specification MIL-E-5007D specifies the contaminants used. Contaminate is introduced by a variable speed belt feeder up to a maximum concentration of 50 grams/1000 gallons. Water injection flow is 0.01 percent of fuel flow as specified by the Mil Spec or .002 to .015 gpm (7.6 to 56.3 mlpm).
The piping system is all butt welded stainless steel with sanitary flange connections to avoid trapped contaminate and facilitate disassembly for cleaning. Tubing sizes are optimized to keep fluid velocities high enough to maintain suspension of the contaminants in the fuel.
A PC-based National Instruments Labview® data acquisition and control system allows the system to be operated manually or automatically (for a given set of test parameters). Manual contaminant reloading of the belt is required by the operator after 36 inches of belt travel.
The main fuel circuit provides a pressurized supply of the test fuel at the specified flow rates for burn flow and recirculated flow. Temperature of the fuel is maintained at 85 +/- 5⁰F as specified by SAE ARP 1827B.
The elevated reservoir and contaminant belt feeder are accessible by platform. The pumping source is a low-flow, high-head pump with a radial vane impeller. The centrifugal-style pump was selected for its inherent mixing ability that facilitates contaminant suspension in the fluid. The pump is coupled to an electric motor with a variable-frequency drive. Supply pressure is modulated by the pump in concert with flow control valves as required to maintain constant flow through the test article as the contaminant loading changes. Fuel leaving the test article can be split into burn flow and recirculated flows to simulate the aircraft’s fuel system. Burn flow and recirculated flow circuits use flow control valves and ultrasonic flow meters to set and hold specified flow rates. The burn flow circuit is equipped with clean-up filters for removing contaminant, a fullers earth filter for adjusting fuel interfacial tension (IFT) and a coalescing filter for water separation. Manually-operated valves allow the operator to select the test station and the combination of burn flow and recirculated flow circuits desired. Two recirculated flow circuits accommodate the range of recirculated flow. Plate and frame heat exchangers remove heat from the fuel and transfer it to the customers cooling water system.
The test station allocates a gap in the test circuit piping for installation of the test article. Sanitary tube flanges serve as the interface fittings for adaptation to the test article. Two test circuits are required to accommodate the range of flows. Each test circuit has upstream and downstream manual valves to isolate and select the flow paths required. Sample and vent valves allow draining prior to test article removal and installation. The sample valves also permit connection to a particle counter for side stream sampling.
Water Injection Circuit
The influent water concentration and test flow is defined in the test procedure as 0.01 percent by volume. The software uses the target concentration and actual test flow to compute the needed water injection flow rate. Since this flow rate must be provided over a very wide range, a precision piston metering pump and variable speed controller are used for this purpose. The water used in the test is salt water in concentrations defined by MIL-E-5007D.
Pneumatic Supply Circuit
Compressed air is used for powering the control valves on the test stand. A separate compressed air circuit supplies dry purge air to the belt feeder enclosure.
Cooling Water Circuits
Two cooling water circuits remove pumping heat from the jet fuel to maintain a constant test fluid temperature. Each circuit contains a plate and frame style heat exchanger, an electro-pneumatic control valve and inlet/outlet thermometers. Facility cooling water is required for cooling the heat exchangers.
Two electrical cabinets are supplied, one for power distribution hardware and another for control equipment. These cabinets are not rated for placement in a hazardous area. Electrical power is delivered to the power cabinet at 480 volts AC, 3 phase. The 120 VAC power is distributed to the loads of the test stand through circuit breakers mounted in the power cabinet. Devices on the test stand that receive the 120V directly are explosion proof rated devices with wiring methods suitable for Class 1 Division 2 Hazardous area The circuit breakers prevent the various devices from overloading the circuit.
Emergency Stop Provision
E-Stop pushbuttons are located at the front panel and in explosion proof electrical boxes on the test stand at two locations in the Class I Division 2 hazardous area fed by suitable wiring and sealing fittings required for the Class I Division 2 location.
The host computer is a desktop personal computer (PC) with Windows 7.0 installed as the operating system. The computer system includes a laser printer.
National Instruments CompactDAQ distributed I/O hardware platform is Din rail mounted inside an enclosure located in the control room. An Ethernet cable connects the compacDAQ controller to the host computer. Application software for test stand data acquisition and control was developed using the National Instruments Labview development system.
- SAE Aerospace Recommended Practice ARP1827B
- SAE Aerospace Recommended Practice MAP749 rev. B
- International Standard ISO4021