Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
SAE J1117-2019: A Standardized Method for Measuring Hydraulic Valve Pressure Differential-Flow Characteristics
Accurate characterization of pressure drop versus flow rate is essential for selecting and applying hydraulic fluid power valves in off-road self-propelled work machines (per SAE J1116). SAE J1117-2019 provides a uniform procedure for measuring and reporting these pressure differential-flow characteristics, ensuring consistent and comparable data across manufacturers and testing facilities. This recommended practice defines test setup, standardized conditions, accuracy tolerances, data recording, and presentation requirements.
Overview and Scope
The standard applies to hydraulic fluid power valves used in off-road self-propelled work machines. Its purpose is to establish a repeatable method for quantifying the pressure losses associated with significant flow paths through a valve. By using standardized test conditions, the results become reliable for catalog data, system design, and performance comparison. The procedure involves measuring the pressure differential across the valve at various steady flow rates and then subtracting the tare loss of the test circuit to isolate the valve’s contribution.
Test Conditions and Procedure
To ensure repeatability, SAE J1117-2019 specifies stringent tolerances for test conditions. The table below summarizes the required accuracies:
| Test Condition | Maintain Within ± |
|---|---|
| Flow | 2% |
| Pressure | 2% |
| Pressure Differential | 4% |
| Temperature | 3 °C (5 °F) |
| Control Variable | 2% |
Key steps in the procedure include:
- Install the test valve in the circuit, using specified input and output ports.
- Set control variables for the flow path being tested.
- Measure pressure differentials at enough flow increments to produce a well-defined curve (zero to maximum flow Qm).
- Remove the valve and measure the tare pressure loss of the test circuit alone.
- Calculate net ΔP = measured ΔPm – tare ΔPt.
- Plot ΔP versus Q and include required identification on the data plot (valve description, fluid type, temperature, port sizes, control position, date, testing agency, output port pressure at Qm).
Standardized test conditions for catalog data call for a fluid with viscosity 21–26 mm²/s at 50 °C, fluid temperature of 50 °C, and system contamination not exceeding ISO 4406 code -/17/14. For subplate-mounted valves, the subplate may be included in the test, and the report must clearly indicate this.
🛠️ Engineering Design Insights and Best Practices
🔍 Design Insight
Using the standardized viscosity (21–26 mm²/s at 50 °C) and temperature (50 °C) ensures that published catalog curves are comparable across different valve types and manufacturers. Always subtract the tare pressure — this isolates the valve’s true pressure loss from the test circuit’s parasitic losses. Plotting the curve with sufficient resolution between zero and maximum flow reveals both low-flow leakage characteristics and high-flow saturation behavior.
⚠️ Common Pitfalls
Failing to subtract tare loss is the most frequent error. Others include using non-standard fluid or temperature, not maintaining test condition tolerances (especially temperature stability), omitting required information on the data plot, and allowing excessive contamination. Always document the control position and port sizes, as these significantly affect the flow characteristic.
Frequently Asked Questions
Why is tare pressure subtracted?
The tare pressure represents the loss due to the test circuit components (e.g., pipes, fittings, filters) separate from the valve. Subtracting it gives the net pressure loss caused solely by the valve, which is the performance of interest.
What fluid is recommended for standard catalog tests?
SAE J1117 specifies a fluid with viscosity of 21–26 mm²/s at 50 °C (approximately ISO VG 32). This ensures consistent results and comparability across different test setups.
How many data points are needed for the curve?
The standard requires enough points between zero flow and the specified maximum flow to produce a well-defined curve. Typically 8–15 points are sufficient to capture the shape, especially the transition from laminar to turbulent regimes.
Can the test be performed with the valve subplate included?
Yes. For subplate-mounted valves, the test may be run with the subplate. However, the report must explicitly state whether the subplate was included, as subplate geometry can affect pressure drop.
