Submerged multi nozzle sleeve valve

Submerged porous sleeve pressure reducing valve

1. Working principle of submerged porous sleeve pressure reducing valve

2. What are the common faults of submerged porous sleeve pressure reducing valve

3. Troubleshooting method for submerged porous sleeve pressure reducing valve

4. What are the requirements for installing submerged porous sleeve pressure reducing valves

5. What are the precautions for submerged porous sleeve pressure reducing valves

Submerged porous sleeve pressure reducing valve is a valve that adjusts the inlet pressure to a certain required outlet pressure, and relies on the energy of the medium itself to automatically maintain stable outlet pressure. From the perspective of fluid mechanics, a pressure reducing valve is a throttling element with variable local resistance. By changing the throttling area, the flow velocity and kinetic energy of the fluid are altered, resulting in different pressure losses and achieving the purpose of pressure reduction. Then, relying on the adjustment of the control and regulation system, the fluctuation of the pressure behind the valve is balanced with the spring force, so that the pressure behind the valve remains constant within a certain error range.

Working principle of submerged porous sleeve pressure reducing valve

The working principle is that the pressure reducing valve reduces water pressure by relying on the local resistance of the flow channel inside the valve to the water flow. The range of water pressure reduction is automatically adjusted by the inlet and outlet water pressure difference on both sides of the thin film or piston connected to the valve disc. The principle of fixed ratio pressure reduction is to use the water pressure ratio control of the floating piston in the valve body, and the pressure reduction ratio at the inlet and outlet ends is inversely proportional to the area ratio of the piston on the inlet and outlet sides. This pressure reducing valve works smoothly without vibrationThere is no spring inside the valve body, so there is no concern of spring corrosion or metal fatigue failure; Good sealing performance without leakage, thus reducing both dynamic pressure (when water flows) and static pressure (when flow rate is 0); Especially when reducing pressure without affecting water flow.

A pressure reducing valve is a type of valve that adjusts the flow rate of the medium by controlling the opening of the opening and closing components inside the valve body, reducing the pressure of the medium. At the same time, the opening of the opening and closing components is adjusted by the pressure behind the valve to maintain the pressure within a certain range. Cooling water is sprayed into the valve body or behind the valve to reduce the temperature of the medium. This type of valve is called a pressure reducing and temperature reducing valve, which maintains the outlet pressure and temperature values within a certain range when the inlet pressure continues to change.

What are the common faults of submerged porous sleeve pressure reducing valve

(1) Export pressure is almost equal to import pressure, without pressure reduction

This fault phenomenon is manifested as: the inlet and outlet pressures of the pressure reducing valve are almost equal, and the outlet pressure does not change with the rotation adjustment of the pressure regulating handle. The causes and elimination methods are as follows.

　　① Due to burrs on the main valve core or the edge of the sunken groove in the valve body hole, or dirt stuck in the gap between the main valve core and the valve body hole, or due to excessive tolerance of the main valve core or valve hole shape, hydraulic clamping occurs, and the main valve core is stuck at the maximum opening position. Due to the large opening, the oil does not reduce pressure. At this point, methods such as deburring, cleaning, and repairing the valve hole and valve core accuracy can be adopted according to the above situation to eliminate it.

　　② Due to the tight fit between the main valve core and the valve hole, or the valve hole or core being pulled during assembly, the valve core may be stuck in the maximum opening position. At this time, a reasonable clearance can be selected. The clearance between pressure reducing valves is generally between 0.007-0.015mm. Before fitting, the valve hole can be ground appropriately before fitting the valve core.

　　③ The short damping hole or valve seat hole of the main valve core is blocked, and the automatic adjustment function is lost. The spring force of the main valve pushes the main valve to the maximum opening, becoming a straight through unobstructed flow, and the inlet pressure is equal to the outlet pressure. The damping hole can be blown through with a diameter of 1 or Omm steel wire or compressed air, cleaned and reassembled.

　　④ The damping element with a damping hole for the pressure reducing valve is pressed into the main valve core, and may be ejected due to insufficient interference during use. After flushing out, the pressure in the inlet and outlet chambers is equal (without damping), and the force area on the valve core is equal. However, there is a spring in the outlet chamber, so the main valve core is always in the maximum opening position, making the outlet pressure equal to the inlet pressure. At this point, it is necessary to reprocess the damping component with a slightly larger outer diameter and re press it into the main valve core.

　　⑤ The oil drain hole of the pressure reducing valve is plugged with an oil plug when it leaves the factory. When this oil plug is not unscrewed and used, it traps oil in the upper chamber (spring chamber) of the main valve core, causing the main valve core to be at its maximum opening without reducing pressure. The pressure reducing valve is the same as this. If the installation plate of the J-type plate valve is designed without connecting the L port to the oil tank, this phenomenon may also occur.

　　⑥ It is easy to install the valve cover in the wrong direction (90 ° or 180 °) when disassembling and repairing the pressure reducing valve, which can block the oil outlet and prevent oil discharge, resulting in the same trapped oil phenomenon as above, causing the main valve to be stuck at the maximum opening without pressure reduction. When repairing, simply install the valve cover in the correct direction.

　　⑦ When the direction of the pressure reducing valve top cover is installed incorrectly, it will cause the output oil hole to communicate with the drain hole, resulting in no pressure reduction. Attention should also be paid.

(2) The export pressure is very low, even if the pressure regulating handwheel is tightened, the pressure cannot rise

　　① The inlet and outlet of the submerged porous sleeve pressure reducing valve are connected in reverse: the installation plate design for the plate valve is incorrect, and the connection for the tube valve is incorrect. The inlet and outlet of the pressure reducing valve are exactly opposite to those of the Y-shaped relief valve. Please pay attention to the steel seal markings (Pl, P2, L, etc.) near the oil port on the valve when using it, or refer to the hydraulic component product catalog. Do not make design or connection errors.

　　② The inlet pressure is too low, and after passing through the pressure reducing valve core and throttling port, the output pressure from the outlet is even lower. At this time, the reason for the low inlet pressure should be identified (such as a malfunction of the relief valve).

　　③ If the load in the downstream circuit of the pressure reducing valve is too small and the pressure cannot be established, it is possible to consider connecting a throttle valve in series downstream of the pressure reducing valve to solve the problem.

　　④ The contact between the pilot valve (cone valve) and the valve seat fitting surface is poor due to the retention of dirt, resulting in poor sealing; Or the pilot cone valve has serious scratches, and the valve seat is out of roundness and has gaps, causing the pilot valve core to not fit tightly with the valve seat hole.

　　⑤ During disassembly and repair, the cone valve is missing or not installed in the valve seat hole. For this, the assembly or sealing condition of the cone valve can be checked.

　　⑥ The long damping hole on the main valve core is blocked by dirt, as shown in Figure 3-21. The oil in chamber P2 cannot flow into the main valve spring chamber through the long damping hole e, and the feedback pressure from chamber P2 cannot be transmitted to the pilot cone valve, causing the pilot valve to lose its regulating effect on the outlet pressure of the main valve. After the damping hole is blocked, the main valve P. The chamber loses the effect of the oil pressure p3, making the main valve a linear spool valve with weak spring force (only the main valve balance spring). Therefore, when the outlet pressure is very low, the force of the balance spring can be overcome to close the throttle port of the pressure reducing valve YMIN. In this way, the inlet pressure p1 is greatly reduced to p2 through the YMIN throttle port, and the outlet pressure cannot increase. The long damping hole should be unobstructed.

　　⑦ The pilot valve spring (pressure regulating spring) is mistakenly installed as a soft spring, or due to spring fatigue causing deformation or breakage, the p2 pressure cannot be adjusted high and can only be adjusted to a certain low set value, which is far below the maximum regulating pressure of the pressure reducing valve.

　　⑧ The pressure regulator handle cannot be fully tightened due to thread strain or insufficient effective depth, resulting in the inability to adjust the pressure to the maximum.

　　⑨ The sealing between the valve cover and valve body is poor, resulting in severe oil leakage. The possible causes may be missing or damaged O-rings, loose clamping screws, and errors in the flatness of the end face during valve cover processing, which are generally convex on all sides and concave in the middle.

　　⑩ The main valve core is stuck in a small opening position due to dirt, burrs, etc., resulting in low outlet pressure. Can be cleaned and deburred.

(3) Unstable voltage, large pressure oscillation, and sometimes loud noise

According to relevant standards, the pressure swing of the pressure reducing valve is± o, 1MPa, which is ± o, 3MPa. Exceeding this standard indicates large pressure oscillation and unstable pressure.

　　① The pressure reducing valve is a pilot operated valve, which is compatible with the relief valve. Therefore, the causes and elimination methods of large pressure oscillations can refer to the relevant parts of the relief valve.

　　② When the submerged porous sleeve pressure reducing valve is used beyond the rated flow rate, the main valve often oscillates, causing the pressure reducing valve to become unstable. At this time, the outlet pressure undergoes a cycle of "increasing pressure and decreasing pressure again and again", so it is necessary to choose a pressure reducing valve that is suitable for the model and specifications.

　　③ The back pressure on the oil drain port L is high, which can also cause pressure oscillations and instability. It is recommended to return oil separately from the oil drain pipe.

　　④ If the spring is deformed or has poor stiffness (due to poor heat treatment), resulting in large pressure fluctuations, a qualified spring can be replaced.

(4) After setting the work pressure, the pressure at the oil outlet increases automatically

In the pressure reducing control circuit, the outlet pressure of the pressure reducing valve is used to control the size of the control oil pressure of the electro-hydraulic reversing valve or external control sequence valve. When the electro-hydraulic reversing valve or external control sequence valve changes direction or works, the outlet flow rate of the pressure reducing valve becomes zero, but the pressure still needs to maintain the originally set pressure. In this case, since the outlet flow of the valve is zero, the flow through the pressure reducing port is only the pilot flow. Due to the low pilot flow rate, it is generallyWithin 2L/min, the pressure reducing port of the main valve is basically close to the fully closed position (with a very small opening), and the pilot flow flows out from the triangular groove or inclined cone surface. If the main valve core is too loose or worn out, the leakage will increase. According to the law of flow continuity, this part of the leakage must also flow from the damping hole of the main valve core, that is, the flow through the damping hole is composed of two parts: the pilot flow and the leakage. However, the damping hole area and the oil pressure in the main valve spring chamber remain unchanged (the oil pressure in the spring chamber is determined by the pre compression of the pressure regulating spring that has been adjusted). In order to increase the flow through the damping hole, it will inevitably cause an increase in the oil pressure in the lower chamber of the main valve. Therefore, when the outlet pressure of the pressure reducing valve is set, if the outlet flow rate is zero, the outlet pressure will increase due to loose fitting or excessive wear of the main valve core.

Troubleshooting method for submerged porous sleeve pressure reducing valve

Fault phenomenon: Unstable pressure fluctuations

Fault analysis:

1. Air mixed into the oil

2. Damping holes are sometimes blocked

3. The roundness of the slide valve and the inner hole of the valve body exceeds the specified limit, causing the valve to get stuck

4. The spring is deformed or stuck in the slide valve, making it difficult for the slide valve to move or the spring is too soft

5. The steel ball is not round, the steel ball does not fit well with the valve seat, or the cone valve is not installed correctly

Exclusion method:

1. Remove air from the oil

2. Clean the damping hole

3. Repair and research valve holes and slide valves

4. Replace the spring

5. Replace the steel ball or disassemble the cone valve for adjustment

Fault phenomenon: The secondary pressure does not rise high

Fault analysis:

1. Leakage and leakage

2. Poor contact between cone valve and valve seat

Exclusion method:

1. Replace seals, tighten screws, and ensure even torque distribution

2. Repair or replace

Fault phenomenon: does not have a pressure reducing effect

Fault analysis:

1. The oil drain port is blocked; The drain pipe is connected to the return pipe and has a return oil pressure

2. The main valve core is stuck in the fully open position

Exclusion method:

1. The drain pipe must be separated from the return pipe and returned to the oil tank separately

2. Repair and replace parts. Check the oil quality

What are the requirements for installing submerged porous sleeve pressure reducing valves

1. The installation of pressure reducing valves should be carried out after the water supply network has passed the pressure test and flushing.

2. Before installing the pressure reducing valve, it should be checked that its specifications and models are consistent with the design; There should be no looseness in the external control pipeline and the connecting parts of the directional valve; The appearance should be free of mechanical damage and foreign objects inside the valve should be removed.

3. The water flow direction of the pressure reducing valve should be consistent with the water flow of the water supply network.

4. Filters should be installed on the inlet side, and control valves should be installed before and after them.

5. Adjustable pressure reducing valves should be installed horizontally, with the valve cover facing upwards.

6. Proportional pressure reducing valves should be installed vertically; When installed horizontally, the orifice of a single breathing hole pressure reducing valve should be downward, and the orifice of a double breathing hole pressure reducing valve should be in a horizontal position.

7. When installing a pressure reducing valve without a pressure gauge, a pressure gauge should be installed adjacent to the front and rear of the valve.

What are the precautions for submerged porous sleeve pressure reducing valves

1. For the convenience of operation and maintenance, this valve is generally installed upright on a horizontal pipeline.

2. The installation of submerged porous sleeve pressure reducing valve must strictly follow the arrow direction on the valve body to maintain consistency with the fluid flow direction. If the water quality is not clean and contains some impurities, a filter must be installed at the upstream inlet of the pressure reducing valve.

3. To prevent overpressure behind the valve, a pressure reducing valve should be installed at a distance of no less than 4M from the valve outlet.

4. The pressure reducing valve plays a certain check role in the pipeline. In order to prevent the harm of water hammer, a small expansion tank can also be installed to prevent damage to the pipeline and valve. The filter must be installed in front of the inlet pipe of the pressure reducing valve, and the expansion tank must be installed after the outlet pipe of the pressure reducing valve!

5. If you need to install a pressure reducing valve in a hot water system, you must install a check valve between the pressure reducing valve and the expansion tank. This not only allows the expansion tank to absorb the increased volume of water due to thermal expansion, but also prevents the impact of hot water reflux or pressure fluctuations on the pressure reducing valve, ensuring its long-term normal operation.