Hydraulic Valve Inspection Instruction

A. Hydraulic Valve For The Test Before The Preparation Of Work.

1. Clean bench and working environment, work apparatus, etc..
2. Carefully and carefully read the technical standards and documents with reference to this tested valve testing parameters, technical conditions, etc..
3. Check the appearance of the valve under test (visual inspection).
4. Check the internal cavity of the valve under test, sealing surface cleanliness (visual inspection, feel no foreign matter).

B. Turn On The Machine:

1. Close the power supply, turn on the oil pump, so that the oil circulation in the oil circuit for ten minutes.
2. Test the test bench oil source, oil pressure is up to standard; (adjust the flow of the oil source, and should be greater than the test flow required by the valve being tested. The pressure of the oil source should be able to exceed the nominal pressure of the valve under test for a short period of time by 20% to 30%.)
3. Check the inner diameter of the pipeline and pipe fittings connected to the valve under test should be consistent with the actual diameter of the valve under test.
4. Allowed to add in the given basic circuit to adjust the pressure, flow or ensure the safe working of the test system components, but should not affect the performance of the valve under test.
5. The import pressure measurement point should be set in the source of disturbance (such as valves, elbows, etc.) between the downstream and the upstream of the valve under test, and the distance between the source of disturbance is not less than 10d (d is the inner diameter of the pipe), and the distance between the valve under test is not less than 5d; export pressure measurement point should be set in the downstream of the valve under test is not less than 10d.

C. The test work:

1. Durability: under rated operating conditions, the valve under test should be able to withstand the required number of actions, its parts shall not have abnormal wear and other forms of damage, the performance indicators shall not exceed 10% of the specified value.
2. Sealing: under rated conditions, the test valve static seal shall not seep oil, the dynamic seal shall not drip oil.
3. Pressure resistance: the test valve pressure port should be able to withstand the highest working pressure of the port 1.5 times, there shall be no external leakage and parts damage and other phenomena.
4. Working pressure range; flow adjustment range; opening pressure; internal and external leakage; pressure loss, oscillation, offset; unloading pressure; flow characteristics; action reliability; regulating torque; transient characteristics; commutation performance; response time; decompression stability; noise; and so on according to the relevant testing standards of the valve under test.
5. The measurement accuracy level is divided into A, B, C three levels. The allowable error of the measurement system corresponding to each level should be in accordance with the provisions of Table 1.
6. The specific operation of the test work, according to the relevant technical standards of the tested valve and the technical specifications in the document to guide the implementation of the test work completed.
7. The tested valve must be neatly placed after the test, timely packaging, and good archival records.
8. Unqualified valve must be marked, stacked separately, and timely processing.

D. Shutdown:

1. Unload all the valves under test, clean up the test work console.
2. First shut down the oil pump motor, and then pull down the main gate.
3. Wipe clean the test bench, clean the working environment.

E. Hydraulic Valve Test Bench Maintenance, Maintenance:

1. The viscosity of the test valve test medium to be regularly analyzed and tested to ensure that the viscosity of the oil movement at work 42mm2 / s ~ 74mm2 / s (40 ℃), (special requirements are specified).
2. Regular cleaning of the oil filter, before and after the shift to check the leakage of the joints and valves at each connection of the oil circuit. Do a good job of no leakage.
3. Before and after shifts to check the use of measuring instruments, the degree of accuracy, timely detection of problems timely rectification and elimination.

F. Hydraulic Valve Inspection Record Filling:

1. The test records of the inspected valve must be filled out in real time, accurate and clear, true and reliable, complete and comprehensive; fill in the font neatly, no scribbling.
2. The product model and number of the inspected valve should be filled out accurately and comprehensively.
3. The inspected valve when the average display value of the controlled parameters do not exceed the range of changes in the value specified in Table 2, considered steady-state conditions. The measured value of the test parameters should be recorded under steady-state conditions.
4. Type test, the number of measured readings of the test parameters and the distribution of the readings taken should reflect the performance of the valve under test in the entire range.
5. In order to ensure the repeatability of the test results, the test parameters should be measured at specified intervals before filling in.
6. The test record is completed, the inspector should sign and indicate the time and date.

Three Major Types Of Hydraulic Valve Pressure Testing Procedures:

Pressure control valve testing procedures

1. a) Appearance quality: the surface should be bright and clean, uniform color, there should be no scars and other defects.
2. b) assembly quality: component assembly must be strictly in accordance with the technical drawings and documents, the product assembly after the relative moving parts action flexible, positioning obvious, the seal shall not have scratches and cut edges.
3. c) Regulating range and pressure stability: No abnormal noise and vibration and other abnormal phenomena in the regulating range. Regulating range: 9~31.5Mpa, pressure oscillation, voltage offset ±0.5Mpa.
4. d) internal leakage: rated flow rate of 40L/min for ≤ 450ml/min, 100L/min for ≤ 480ml/min, 200L/min for ≤ 510ml/min.
5. e) Pressure loss: The differential pressure should be less than or equal to the specified value. The rated flow rate of 40L/min is ≤0Mpa, 100L/min is ≤2.5Mpa, 200L/min is ≤1.5Mpa.
6. f) Other pressure characteristics: open rate ≥ 75%; closure rate ≥ 70%.
7. g) Back pressure sealing: no external leakage.
8. h) Unloading pressure.
9. i) Action reliability: when the solenoid is energized or de-energized, the system can unload or depressurize, and there shall be no abnormal phenomena such as squeaking sound.

2.Solenoid valve testing procedures.

1. a) Appearance quality: the surface should be bright and clean, uniform color, there should be no scars and other defects.
2. b) Assembly quality: component assembly must be strictly in accordance with the technical drawings and documents, the product is assembled relative to the moving parts action is flexible, positioning is obvious, the seal shall not have scratches and cut edges.
3. c) Working differential pressure: solenoid valve can open and close normally within the working differential pressure range, flexible action, no abnormal sound.
4. d) Power supply voltage changes: when the voltage deviates from the rated value of -15% and +10%, should be able to open and close normally. (5% random inspection)
5. e) Insulation resistance: measuring the insulation resistance between the terminal and the shell ≥ 20MΩ. (5% sampling)
6. f) Dielectric strength: can withstand 50Hz voltage 1500V over 1min test without breakdown and no flying arc phenomenon. (5% sampling)
7. g) Leakage: in the test pressure 31.5Mpa allowable leakage is not more than 80ml/min.
8. h) Sealing: at 1.1 times the nominal pressure, there should be no leakage.
9. i) Pressure strength: under 1.5 times the nominal pressure, there should be no leakage and damage.
10. Flow control valve testing procedures.
11. a) Appearance quality: the surface should be clean, uniform color, no scars and other defects.
12. b) Assembly quality: component assembly must be strictly in accordance with the technical drawings and documents, the product assembly after the relative moving parts action flexible, positioning obvious, the seal shall not have scratches and cut edges.
13. c) Internal leakage: (one-way throttle valve) ≤360ml/min.
14. d) External leakage: static seal and dynamic seal should be free of leakage.
15. e) Pressure loss: (positive) ≤4Mpa.

Permissible Systematic Error Of The Measurement System

Allowable Range Of Variation Of The Average Display Value Of The Controlled Parameter