Common pressure relief valve noise problem

Commonly used pressure valve noise problem pressure valve is used for a long  time will produce noise, pressure valve noise is three reasons, the following  small make up with you to talk about pressure valve noise. The commonly used  pressure relief valve is divided into membrane type, spring type and piston type  according to the structural form, according to the action form is divided into:  proportional type and constant pressure (adjustable) type. Constant pressure  (adjustable) pressure reducing valve has a kind of both dynamic pressure  reduction, static pressure reduction, and the pressure before the valve can be  left to change, and the pressure after the valve can be stable in the required  pressure pressure pressure regulator valve. When reducing pressure valve is used  for water supply zoning in the fire extinguishing water supply system, in order  to meet the requirements of static and dynamic pressure of the fire  extinguishing port in the code, it is advisable to use the adjustable film  reducing valve which can reduce dynamic pressure and static pressure, and also  has the function of stabilizing pressure.

Common pressure valve noise problems pressure valve noise can be divided into  the following three categories:

1. Pressure reducing valve mechanical vibration noise;

2. Fluid dynamics noise; 

3. Aerodynamic noise.

A common pressure valve noise problems caused by mechanical vibration  noise

Valve Supplier China

Pneumatic control valve parts in the flow of fluid will produce mechanical  vibration, mechanical vibration can be divided into two forms:

(1) low frequency vibration. This vibration is caused by the fluid flow and  pulsation of the medium, which is caused by the valve outlet velocity is too  fast, the pipeline layout is not reasonable and the valve parts are not rigid  enough.

(2) high-frequency vibration. This kind of vibration is in the natural  frequency of the valve and medium flow caused by the excitation frequency  consistent, hydraulic control valve will cause resonance, it is the pressure  reducing valve in a certain decompression range, and once the condition has a  little change, its noise change is very big. This kind of mechanical vibration  noise has nothing to do with the velocity of medium flow, which is mostly caused  by the unreasonable design of the pressure-reducing valve itself. The measures  to reduce the mechanical vibration noise are to design the clearance of valve  bushing and valve stem reasonably, machining accuracy, natural frequency of  valve and rigidity of moving parts, and to choose the correct materials.

We supply Cast steel Check Valve, Cast Steel Gate Valve, etc., welvome to puechase our valves.

Pneumatic control valve debugging

Pneumatic control valve debugging by valve supplier.

Pneumatic Drive Type Butterfly Valve before use, focus on the spring preload, neutral point, E/P converter, locator, etc., to meet the valve stroke, valve displacement linear, switching time, leakage and other performance indicators. Before commissioning, (1) the process pipeline must be purged strictly; (2) the handwheel mechanism should be in the "release" position; (3) check whether the pressure of reducing valve air supply meets the gas supply requirements.

1. BenchSet adjustment method

To prevent the valve from closing or opening, the actuator must be adjusted before it is installed into the valve body.

According to the upper and lower limits of pre-tightening force required by the valve nameplate, a simple special adjustment tool is used to adjust the initial spring force.

Open and close the valve several times by inflating the exhaust to ensure smooth movement of the pneumatic head.

Press the pneumatic head, record the pressure just moved by the pneumatic head connecting rod and compare it with the lower limit of pre-tightening force on the valve nameplate, adjust the spring pre-tightening force adjusting nut until the pressure reading when the pneumatic head connecting rod just moved is the lower limit.

Continue to increase the pressure to the upper limit and mark the stem as the pneumatic head link moves to the end of the body.

Slowly pneumatic air pressure drop back to the lower limit value, record the valve stem tags, the distance to the pneumatic head end of the connecting rod with the valve nameplate schedule is consistent, if consistent, adjusting spring pre-tightening force and prove that the valve closed or open enough force in natural state, or need to replace the spring, reinstall and according to the above steps to carry on the adjustment of the pre-tightening force.

2. Setting of NEUTRALPOINIT

The neutral point is that the handwheel is adjusted to the position that does not affect the automatic adjustment. It may be a point or an area. Too high a neutral point will cause internal leakage, and too low a setting will easily lead to insufficient flow. Usually valve isolation or automatic failure, often by destroying the neutral point of pneumatic control valve to achieve the valve fully open, fully closed or maintain a certain degree of opening. Usually have only need to handle the neutral point of roller skating piece of the neutral point of a pointer on the scale on the neutral line, also can be adjusted by hand ", loss of air pressure to open the pneumatic valve "neutral point set, should make the pneumatic valve in a loss of air pressure, full open position the handwheel clockwise in the direction of the clearance of rotating until feel resistance under the instructions manual lever to guide bush check, and then counter-clockwise 1/2 circle rotate in the direction of the open"; Set the neutral point of the pneumatic valve in the direction of deaeration and turn the handwheel counterclockwise to the open direction until the resistance is felt, indicating that the manual rod reaches the stop position of the guide sleeve, and then rotate 1/2 turn clockwise to the direction of the close. Adjust to the neutral point position with the hand wheel lever lock lock.

3. Check electrical converter (E/P)

The current source is used to provide 4mA ~ 20mA dc current signal, and the SAR provides compressed air.

Take the positive action pneumatic control valve as an example to carry on the following adjustment, its output pressure must meet the precision requirements.

Zero adjustment, input 4mA current signal, turn the zero adjustment screw to read the pressure gauge data until the output pressure is 20kPa.

Adjust range, input 20mA current signal, adjust range adjustment screw until output pressure 100kPa.

Linear check, input 8, 12, 16mA, output pressure is 40, 60, 80kPa.

Repeat until the precision requirement is met.

4. Check valve positioner

Take the pressure signal of 20kPa ~ 100kPa from E/P converter as the input signal of the locator. First open the air source of the locator to check the smooth operation of the locator.

Adjust the input signal to half of the range, open the air source, then the locator rotating arm should be in the horizontal position, the valve should be 50% open, otherwise check whether there is a leak or whether the locator CAM installation is proper.

Adjust zero so that the positioner is entered at zero, loosen the nozzle lock screw, and adjust the nozzle until the valve corresponds to the fully closed (or fully open) position.

Adjust the range so that the positioner input is full, adjust the position of nozzle baffle, so that the valve corresponds to the full open (or closed) position.

Check whether the valve meets the requirements of 0%, 25%, 50%, 75% and 100% opening at the input pressure of 20, 40, 60, 80 and 100kPa respectively, or make repeated adjustment.

Test method and procedure for seat leakage of v-type ball valve

1. Preparation,

Prepare the pressure flange corresponding to the High Temperature Ball Valves China tested and check whether the o-ring is intact. If damaged, timely replace it;

Be prepared to test the leakage with a measuring cup or flowmeter that is more accurate than ±10% of the reading value of the leakage allowed by the valve being tested.

2. The v-type ball valve under test is fixed with the pressure testing flange

Lift the tested v-shaped ball valve on the pressure test equipment (special plane) with lifting equipment, and properly position the "O" ring and clamp it. (note: v-shaped ball valve is not allowed to be separated from lifting equipment before the end of the test)

Clamp the pressure testing flange and v-shaped ball valve tested with bolts and nuts.

3. Input the specified signal pressure to the air chamber of the actuator and apply the required valve closing torque to make the v-type ball valve in the closed position. Actuator input signal pressure values are shown in table 2.

4. Input test medium for v-shaped ball valve under test, and adjust the medium pressure to the specified value:

Metal seal: test medium is normal temperature water or air;

Soft seal: test medium is air;

When the test medium is normal temperature water, the test pressure is 1.1pn.

When the test medium is air, the test pressure is 0.6mpa.

Note: when the test medium is normal temperature water, anti-rust agent should be added in the water to prevent rust.

5, the measured v-type ball valve input media pressure, make v-type ball spool action 2 ~ 3 times after closing, when the leakage of v-type ball valve is stable, measured at the outlet of v-type ball valve leakage.

6. Apply test pressure according to the specified flow direction;

7. Remove the v-shaped ball valve to be measured from the pressure test machine, empty the residual water in the valve, and blow dry the residual water with compressed air.

What is the definition and working principle of the regulating valve?

In the process of using the pneumatic ball valve to adjust the valve, what is its working principle and what is the definition of the regulating valve? Below High Temperature Ball Valves China will sort out the definition of the regulating valve and the working principle.

The throttle valve is one of the widely used valves. It is popular because it has small friction between the sealing surfaces during opening and closing, is relatively durable, has low opening height, is easy to manufacture, and is easy to maintain. Medium and low pressure, and suitable for high pressure. The closing principle of the regulating valve is that the valve sealing surface is closely adhered to the sealing surface of the valve seat by the pressure of the valve bar to prevent the medium from flowing.

As one of the most important shut-off valves, the regulating valve plays an important role in the aerospace industry. As an important component of aerospace equipment, the regulating valve realizes the functions of medium conveying, cutting off and adjusting, and its sealing performance directly affects the safe and reliable operation of aerospace equipment. Studying the influencing factors and influence laws of the sealing characteristics of typical regulating valves, it has guiding significance for the structural design of the valve sealing pair, thus improving the sealing performance and reliability of the valve.

The above is the relevant description of the regulating valve. If you have any questions, please feel free to contact us. We will update you more and pay attention to our website.

[Valve supplier] How to solve the regulator leakage problem?

Cast Iron Check Valve Supplier shares that regulating valves are the main type of actuators that change fluid flow  through dynamic operation by receiving control signals from the regulating  control unit. Control valves are generally composed of actuators and valves. If  according to its matching actuator power, control valve can be divided into  pneumatic, electric, hydraulic three. Below we say the control valve several  common faults and solutions.

In the modern factory automation control system, the control valve, as the  terminal actuator of the automatic control system, receives the control signal  to realize the adjustment of chemical process. Its motion sensitivity is  directly related to the quality of the regulating system. According to the  actual statistics on the scene about 70% of the fault from the control valve.  Therefore, the factors and countermeasures affecting the safe operation of  control valve are summarized and analyzed in daily maintenance.

The following analysis of several common leakage fault phenomenon, put  forward countermeasures.

Leaks in the valve

Uncomfortable stem length. Open valve, stem too long stem up (or down)  distance is not enough, resulting in a gap between the valve core and the seat,  not enough contact, resulting in lax closure and leakage. The same air off valve  stem is too short, resulting in a gap between the valve core and the seat, not  enough contact, resulting in lax closure and leakage.

Solutions:

Should shorten (or extend) the control valve stem to make the control valve  length appropriate, so that it is no longer internal leakage.

Packing leakage

After the packing is loaded into the packing box, axial pressure is applied  to it through the gland. The packing is plastic, causing radial force and close  contact with the stem, but this contact is not very uniform. Some parts are  loose, some parts are tight, and some parts are not touching at all. Control  valve in the use of the process, there is a relative movement between the stem  and packing, this movement is called axial movement. In the process of use High Temperature Ball Valves China, with  the high temperature, high pressure and strong permeability of the fluid medium,  the control valve packing box is also the location of leakage phenomenon more.  The main cause of packing leakage is interfacial leakage, and there will be  leakage for textile packing (pressure media leak outward along the tiny gap  between packing fibers). The interface leakage between the stem and the packing  is caused by the gradual attenuation of the contact pressure of the packing, the  packing itself aging and other reasons, at this time the pressure medium will  leak outward along the contact gap between the packing and the stem.

Solutions:

In order to facilitate packing loading, a metal protective ring with small  erosion resistance clearance is placed at the bottom of packing box to prevent  packing from being pushed out by medium pressure. Stuffing box each part and the  packing contact part of the metal surface to finish processing, in order to  improve the surface finish, reduce the packing wear. Flexible graphite packing  is chosen, because of its good air tightness, friction small, use for a long  time after the change is small, the wear loss is small, easy maintenance, gland  bolts to tighten, do't change after the friction pressure resistance and heat  resistance, good internal media, contact with the valve stem and gland internal  metal corrosion pitting or not. In this way, effectively protect the valve stem  packing box seal, and ensure the reliability and long-term packing seal.

Spool, valve seat deformation leakage

The main cause of spool and seat leakage is the strengthening of corrosion  caused by casting or forging defects in the production of control valves. And  corrosive medium through, fluid medium erosion can also cause the leakage of the  control valve. Corrosion mainly exists in the form of erosion or cavitation.  When the corrosive medium through the control valve, it will produce erosion and  impact on the valve core, valve seat material into an oval or other shape, as  time goes by, leading to the valve core, valve seat is not matched, there is a  gap, close lax leakage.

Solutions:

The key to the valve core, valve seat material selection, quality. Choose  corrosion - resistant materials, pitting point, trachoma and other defects of  the product resolutely removed. If the valve core, valve seat deformation is not  too serious, can be ground by fine sandpaper, eliminate traces, improve the  sealing smoothness, in order to improve the sealing performance. If the damage  is serious, it should be replaced with a new valve.