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Blog - Pressure Relief Valve Testing

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Pressure Relief Valve Testing

Pressure relief valve is called as safety valve sometimes, the valve is often installed in front of the hydraulic pump for protection and keeping the hydraulic pressure in a normal level, therefore it is importance to confirm the quality of pressure relief valve before mounted in the hydraulic system. – finotek.com

The Steps of Pressure Relief Valve Testing:

pressure-valve-testing-symbol

(1-1) Hydraulic pump ; (2) Pressure relief valves ; (3-1, 3-2) Pressure gauges ; (4) Pressure Relief valve tested ; (5) Flow meter ; (6) Flow throttle valve ; (7) Solenoid directional valve ; (8) Electro-hydraulically directional valve ; (9) Thermometer ; (10) 2-Way flow control valve ; (11-1, 11-2) Fine filters

1. Pressure Resistance Test – With the 2% speed rate at per second, pressurize to each oil ports of tested pressure relief valve at 1.5 times of maximum working pressure, then holding the pressure in 5 minutes.

2. Pressure Range & Stability Test – To adjust the pressure of relief valve (part no.: 2) to 115% upper than the maximum adjustable pressure of tested pressure relief valve (part no.: 4),  confirming the hydraulic system pressure equals testing pressure, then testing the following testing terms.
(a) Rotated the hand wheel of tested pressure relief valve (part no.: 4)  from loose to tight condition fully by hand, then observing the pressure adjusting range status by the pressure gauge (part no.: 3-1), it is no less than three times.
(b)  Regulating the tested relief valves (part no.: 4)  to its maximum pressure limits, then measuring the pressure run-out value in one minute by pressure gauge(part no.: 3-1).
(c)  Regulating the tested relief valves (part no.: 4) to its maximum pressure limits, then measuring the pressure offset value in one minute by pressure gauge (part no.: 3-1).

3. Internal Leakage Test – Regulating each the tested pressure relief valve (part no.: 4), and pressure relief valve (part no.: 2) until the system pressure reaches to the maximum adjustable limited pressure value of tested valve (part no.: 4), confirming the pressure on the tested valve (part no.: 4) equals testing required flow rate. Adjusting the pressure relief valve (part no.: 2) to lower the hydraulic system pressure to 75% of maximum adjustable pressure value of tested valve (part no.: 4), checking the internal leakage at relief port of test valve (part no.: 4) after 30 seconds.

4. Pressure Unloading Test – When the flow rate through the tested pressure relief valve (part no.: 4) is testing flow rate, switching the directional control valve (part no.: 7). Measuring both pressure on the inlet and outlet port of the tested valve (part no.: 4) by pressure gauges (part no.: 3-1, 3-2). The differential pressure is unloading pressure. (The test is only for external pilot operated pressure relief valves, including modular style.)

When the flow rate through the tested pressure relief valve (part no.: 4) equals testing flow rate, then energized and de-energized the solenoid of pressure relief valve (part no.: 4). 

Reading the pressure value between the inlet port and outlet port of test valve (part no.: 4) with pressure gauges (part no.: 3-1, 3-2). The differential pressure worked out is unloading pressure (The test is only for solenoid operated pressure relief valves, including modular style.).

5. Pressure Loss Test – Turn the hand wheel of the tested pressure relief valve (part no.: 4) to loose status, confirming the flow rate through the tested valve (part no.: 4) equals test flow rate. To measure the pressure of inlet and outlet of tested pressure relief valve (part no.: 4) by pressure gauges (part no.: 3-1, 3-2), the pressure difference is operation pressure loss. 

6. Pressure Steady & Flow Characteristics – To adjust the pressure relief valve (part no.: 2) until the system pressure equals 115% of tested valve maximum pressure adjustment range. Regulating the tested valve to its maximum pressure range, making sure the flow rate through the tested valve (part no.: 4) is required fluid flow rate, them test the valve as per the terms below:

a. To lower the system pressure gradually by regulating the pressure relief valve (part no.: 2), measuring the tested pressure relief valve (part no.: 4) flow relief rate as soon as the system pressure lowers to its closed pressure at pressure closure rate.

b. Beginning to turn the pressure relief valve (part no.: 2) from no relief condition. Then increasing the system pressure gradually until the pressure is relatively to the open pressure at pressure open rate of tested pressure relief valve (part no.: 4), to measure the relief rate of the tested hydraulic pressure relief valve (part no.: 4).

7. Reliable Response Test – To adjust the pressure relief valve (part no.: 2) until the system pressure equals 115% upper value of tested valve (part no.: 4) maximum pressure adjustment range (Only for safety pressure valve), and the flow rate through tested pressure relief valve (part no.: 4) equals testing pressure. Then adjusting the tested valve 4 to its maximum pressure range, to de-energized and energized the solenoid, observing the unloading and loading pressure of the tested valve by pressure gauge (part no.: 3-1), trial and no less than three times (This test is only for the pressure relief valve with solenoid control type).

8. Leakage Test – a. Back pressure leakage test: To adjust the throttle valve (part no.: 6), holding the back pressure of 0.5MPa at the relief port of tested pressure relief valve (part no.: 4), turn the adjustment hand wheel of tested valve on or off and off to on about 3 minutes, there is no oil on a while paper.

b. Dynamic sealing test: Stuck a white page under the adjustment hand wheel and solenoid coil of tested pressure relief valve (part no.: 4), there is no oil droplets on the white paper while on the testing processing.
C. Static sealing test: After the test, affixed absorbent papers to in the static seal position, there should be no traces of oil.

2017-03-05T01:40:41+00:00