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//Hydraulic Check Valve Testing

Hydraulic Check Valve Testing

The function of hydraulic check valve is to block the fluid flow in one way direction and free flow in the converse direction. There are two type of installation and inner seal: screw-in or subplate connection, and ball or poppet sealing, but the working principle is nearly similar. The pilot operated check valve is complicated a little bite, below is the details of testing the valve. – finotek.com

The Steps Of Hydraulic Check Valve Testing:
1. Pressure Resistance Test – Switching the spool of electro-hydraulically valve to right position, adjust the pressure relief valve(part no.: 2-1), adjusting the pressure from the minimum working pressure to increase gradually at a rate of 2% per second until the tested hydraulic check valve (part no.: 4) reaches its maximum working pressure of 1.5 times and keeping the pressure 5 minutes.

2. Inner Leakage Test – Energized and de-energized three times of electro-hydraulically valve and switching its’ spool to right position, adjust the pressure relief valve (part no.: 2-1) until the B oil port nominal pressure of tested check valve is 1Mpa, then measure the inner leakage at an oil port after 1 minute.

3. Pilot Piston Leakage Test (Only for Pilot operated check valve) – To close the pressure relief valve (part no.: 2-3), to adjust the hand wheel (knob)of  pressure relief valve (part no.: 2-1) to the nominal pressure for the A oil port of pressure of tested hydraulic check valve (part no.: 4). Measuring the pilot piston leakage of tested check valve (Measure X oil port for inlet oil drain valve, measure Y oil port for outlet oil drain valve.)

4. Forward Pressure Loss – Checking the pressure of tested hydraulic check valve (part no.: 4) by pressure gauge (part no.: 3-1 and 3-2) under testing flow rate, the pressure difference between the gauges is pressure loss of tested check valve.
For pilot operated check valve, the forward pressure loss should be tested in the two conditions: zero pilot operated pressure and check valve fully opening by pilot operated pressure.

5. Reverse Pressure Loss – Switching the spool of electro-hydraulically directional valve (part no.: 7) and manually directional valve (part no.: 8) to right position, adjust the pressure relief valve (part no.: 2-2) in order pilot pressure to open the tested check valve fully and reverse flow through the tested hydraulic check valve is testing flow rate. Then to check the pressure by pressure gauges (part no.: 3-2 and 3-1) the pressure difference is the reverse pressure loss of tested check valve (part no.: 4).

6. Opening Pressure – To remove the pipe line on B oil port of tested check valve (part no.: 4), adjust the pressure relief valve (part no.: 2-1), then to increase the A oil port pressure of test check valve (part no.: 4) from low to high gradually. While there is an oil flows from the B oil port of tested check valve (part no.: 4), reading the opening pressure of tested check valve (part no.: 4) from pressure gauge (part no.: 3-1), this test should be not less than three times.

7. Pressure Control Characteristics – There are two parts of this test.
Reverse open minimum control pressure test :
check-valve-testing-symbol

 

(1-1, 1-2) Hydraulic pump
(2-1, 2-2, 2-3) Pressure relief valves
(3-1, 3-2, 3-3) Pressure gauges
(4) Hydraulic Check valve tested
(5) Flowmeter

(6) Flow control check valve
(7) Electro-hydraulically directional valve
(8) Manually directional valve
(9-1, 9-2) Fine filter
(10-1, 10-2) General filter

 

 

 

Switching the valve spool of electro-hydraulically directional control valve and manually operated directional valve to right position, adjust the pressure relief valve(part no.: 2-1, 2-2, 2-3) to meet the following conditions:

a) The B oil port of tested check valve (part no.: 4) is 90% nominal pressure and reverse flow of tested check valve (part no.: 4) is testing flow rate.

b) The pilot operated pressure must be adjusted until open the tested check valve (part no.: 4) fully. At the above testing conditions, to adjust the pressure relief valve (part no.: 2-2) again, increasing the control pressure from zero to upper gradually until the reverse flow rate of in tested check valve (part no.: 4) equals the testing flow rate.  Measuring the minimum control pressure by pressure gauge (part no.: 3-3) when the reverse flow rate equals testing flow rate through tested check valve (part no.: 4), and tested no less than three times.

High pressure test in reverse flow closed:
Switching the valve spool of electro-hydraulically directional control valve and manually operated directional valve to right position, adjust the pressure relief valve (part no.: 2-1, 2-2, 2-3) to meet the following conditions.

a) The oil port pressure of tested check valve should be as low as possible and reverse flow of tested check valve (part no.: 4) is testing flow rate.

b) The pilot operated pressure must open the tested check valve (part no.: 4) fully.
Above the testing conditions: adjust the pressure relief valve (part no.: 2-2) again, to lower the control pressure gradually until the reverse flow closed of pressure relief valve (part no.: 2-2).
To measure the highest control pressure of tested check valve (part no.: 4) by pressure gauge (part no.: 3-3) when reverse flow closed and it should be tested no less than three times.

8. Oil Leakage Tested – Cleanly the directional solenoid valve and valve testing spacing nearby, to confirm the tested hydraulic check valve static seal & dynamic seal as follow;
(1) Static sealing: With a clean absorbent paper attached to the static seal , to remove the paper after trial, if any traces of oil in the absorbent paper is the oil permeability .
(2) Dynamic seal: Place a white paper on dynamic seal at the bottom, to confirm if there is oil drops is dripping on the white paper after the trial.

2017-03-05T01:41:17+00:00

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