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Flow control and pressure regulating valves
Product serial number
1
Product description
Parameters
VT-LT942X piston type flow regulator-Product Description:
1. Overview
The valve is suitable for many media, such as clean water, raw water, sewage, seawater, oil, etc.; Wide range of applicable medium temperature (conveying medium temperature: -50~135oC); It can be widely used in any pipeline system in water conservancy, electric power, water supply and drainage, metallurgy, chemical industry and other industries that requires precise adjustment, safe pressure reduction or flow regulation, and safety two-in-one. It can also be used as a variety of special-purpose valves such as outlet control valves at the bottom of dams, turbine inlet and bypass control valves, shut-off valves under high pressure and high flow rates, and pre-pump check valves.
Citation:
GB/T 1220 stainless steel rod
GB/T 1047 Definition and use of pipe elements DN (Tolerance Dimensions).
GB/T 1048 Definition and use of PN (nominal pressure) for piping elements
GB/T 12220 General Purpose Valve Mark
GB/T 12223 Connection of drive device for partial rotary valve
GB/T 12225 General valve -- Technical conditions for copper alloy castings
GB/T 12227 General valve -- Technical conditions for ductile iron castings
GB/T 12229 General valve -- Technical conditions for carbon steel castings
GB/T 13927 General valve -- Pressure test
GB/T 17241.6 Integral cast iron pipe flange
GB/T 17241.7 Technical conditions for cast iron pipe flanges
JB/T106 Marking and Painting of Valves
JB/T5300 General Purpose Valve Material
JB/T7928 General Purpose Valve Supply Requirements
GB/T 17219 "Safety evaluation standards for drinking water transmission and distribution equipment and protective materials"
Second, the main technical performance
1. The basic principle and structure diagram of piston type pressure regulator are shown in the following figure:
The valve is mainly composed of the main valve composed of valve body, outlet valve body, valve seat, piston, squirrel cage, valve stem, crank, connecting rod, shaft sleeve, guide rail, piston frame and sealing ring, plus electric drive device, PLC control system and pressure sensor (flow meter).
The adjustment of the valve is mainly by changing the medium flow area between the closing part (piston) and the sealing surface of the valve seat, so as to achieve the purpose of regulating the flow rate. The valve body is designed with an inner and outer cylindrical structure, which makes the structure of the valve more in line with the water flow control technology. The adjusting mechanism is a crank slider mechanism, and the sliding block of the closing piece is a cylindrical piston, which can be guided by a guide rail in the cylinder in the valve body to move axially along the center of the pipeline, so as to change the flow area to realize the control and adjustment function. The cavity of the valve body is a streamlined central axis symmetrical flow channel, so that the fluid is well guided in the valve body, with low water resistance and low head loss. The cross-section of the water flow at any position in the valve cavity is annular. The annular throttle surface of the piston in any position ensures the linear operation of the valve. The crank slider mechanism operates stably and reliably, the output torque is constant, and the closing is first fast and then slow, so there is no water hammer.
2. Structural design of adjusting parts
The design of the control valve is generally determined according to the system pressure conditions and the maximum and minimum flow conditions. The requirements and technical conditions vary greatly from one condition to another. When the traditional control valve is used for flow regulation and pressure control, it is extremely difficult to accurately control the output, which is determined by the structure of the control part and the operation and execution mode of the traditional control valve. The piston type flow regulating valve can adapt to the requirements of different working conditions, and has excellent performance and good adaptability, we design the valve body into sections, and the closing adjustment part is designed as a combined split structure. When the system has different requirements, only the shut-off adjustment part needs to be replaced or a small amount of adjustment design can be satisfied. Through the analysis of the operating characteristics of the control valve, we determined that the piston type flow regulating and pressure regulating valve was designed into two standard types: squirrel cage type and fan blade ring type. (Figure 2). 
When the system has special requirements, the design can be modified with a little variation to meet its individual requirements. At the same time, it also solves various technical problems under certain high-demand working conditions, especially in high-precision, large differential pressure and large flow regulation. The pressure level of the piston type flow regulating pressure regulator can reach PN100 or above, and the pressure difference between the upstream and downstream of the valve can reach 4MPa. This bidding is a squirrel cage type.
3. Cavitation damage problem solving
Cavitation damage is a problem that has not been well solved by traditional control valves. The two adjusting structures of the piston type flow regulator and the fan blade type can effectively prevent cavitation damage (Figure 3).
The fan blade ring is made of uniformly distributed guide blades, which divides the upstream medium flow into multiple small streams, and does a spiral flow under the guidance of the fan blade ring. The medium flow is forced to change the flow direction, and the bubbles that produce cavitation are confined to the center of the pipeline, and the rupture of the unstable bubbles is not on the wall of the pipe and the valve, so there is no cavitation damage. The squirrel cage is a cylinder with holes extending out of the front of the piston, the holes are symmetrically and evenly distributed, and the number of holes depends on the working conditions. When the medium flow passes through the cylindrical rattle cage throttle channel, it is divided into multiple high-velocity fluids, which are sprayed radially towards the center of the cage, so that cavitation is confined to the center of the cage, so that there will be no cavitation damage to valves and pipes.
4. Operate the actuator and intelligent control system
The general control valve mostly adopts the mechanical proportional hydraulic control mode, which has the problems of slow response, low accuracy and high failure rate. We have adopted mature modern industrial control technology, computer and network communication technology and other modern technologies in the design of the control system of the piston type pressure regulating valve, and applied the modern control technology to the control system of the regulating valve for the first time (Figure 4). With the programmable controller (PLC) with multiple communication ports and analog modules as the core, various status information of the system is collected through various sensors, and the intelligent control of the valve is realized by using PLC programs. In the steady flow state, it is automatically adjusted by electromagnetic flowmeter tracking according to the downstream flow change, and the upstream and downstream pressure is monitored by the pressure transmitter. 
5. The sealing effect of the piston type pressure regulating valve is good, the main sealing pair is rubber seal, the leakage of the valve is zero, and there is no leakage and leakage pressure boost. Bi-directional bubble level seals are possible.
6. The body of the piston flow regulating valve is integrated casting, which is sturdy and durable. The valve is horizontally arranged, and the connection form with the pipeline is flange connection, and the flange connection size is implemented according to the national standard GB/T17241.6.
7. The piston type flow and pressure regulator has a built-in fluid guide to make the medium flow good, the overflow flow is large, and the cavitation resistance is resistant. The movable parts are located in the inner valve body
No jamming, good flow regime, low vibration noise when working, maximum noise less than 85dB
8. There are lifting lugs on the body of the piston type flow regulating valve, which is easy to install and maintain.
9. The transmission mode of the piston type regulator is driven by the motor, and the motor device is convenient, flexible, safe and reliable, and the manual operation torque is lower than the national standard. The electric device of the piston valve includes a motor, a reduction worm gear, a mechanical limit adjustment mechanism, a torque control mechanism, a stroke control mechanism and an opening indication mechanismSelf-locking worm gear gearbox, stable transmission, accurate positioning, reliable and durable.
10. Piston type flow regulating valve In the process of opening or closing the valve, the valve seat and the sealing ring do not rub against each other, and the valve has a long service life, not less than 20 years. The interval between overhauls shall not be less than 30,000 hours.
11. Electric device for piston valveImported mechatronics design is adopted, and the components are integrated in a closed actuator housing to meet the requirements of remote control and have signal output. (Able to accept remote contact control signals, execute control commands and feedback action signals).
The electric actuator adopts a graphic dot matrix LCD screen to digitally. Graphic display of torque, valve position, limit setting and other working status and alarm, in order to facilitate the user's operation. The electric actuator has the functions of torque protection, automatic phase protection, instantaneous reversal protection, power supply underphase protection, overheating protection, valve position and torque detection, etc., the electric actuator has the function of on-site manual operation of the valve switch
3. The main parts and materials of the piston flow regulating and regulating valve
|
serial number |
name |
Material |
serial number |
name |
Material |
|
1 |
Valve body |
Ductile iron QT450-10 |
9 |
Connecting rod |
1Cr18Ni9 |
|
2 |
Outlet valve body |
Ductile iron QT450-10 |
10 |
crank |
1Cr18Ni9 |
|
3 |
Pressing rings |
1Cr18Ni9 |
11 |
Flat keys |
1Cr18Ni9 |
|
4 |
Seat |
1Cr18Ni9 |
12 |
Sleeve |
QSn6.5-0.1 |
|
5 |
cylinder |
1Cr18Ni9 |
13 |
Outer connecting disk |
Ductile iron QT450-10 |
|
6 |
Seals |
nitrile rubber |
14 |
Stem |
1Cr18Ni9 |
|
7 |
Inner connecting disk |
1Cr18Ni9 |
15 |
Connecting pins |
1Cr18Ni9 |
|
8 |
piston |
1Cr18Ni9 |
16 |
Electric actuators |
/ |
Fourth, the main technical parameters of piston type flow regulating and pressure regulating valves
(1) Type: piston type
(2) Model: LT942X-16Q
(3) Adjustment structure: squirrel cage type
(4) Nominal diameter: DN400-DN1200
(5) Nominal pressure: PN 16
(6) Medium: water
(7) Valve sealing method: soft and hard double seal of metal/rubber
(8) Installation location: at the water distribution port of the water pipeline
(9) Valve installation direction: installed on the horizontal pipeline, the valve shaft is horizontal
(10) Direction of valve electric device: installed on the side of the valve
(11) The structural design pressure of the valve: 1.6MPa
5. Performance acceptance test:
The piston type flow regulating valve must do shell test, seal test and mechanical performance debugging test in the factory.
Housing test: the valve body should bear 1.5 times the nominal pressure for the specified duration, and the shell should not have structural damage and visible leakage;
Sealing test: the valve body bears 1.1 times the nominal pressure for the specified duration, and there shall be no visible leakage between the valve seat and the piston sealing pair;
Mechanical performance adjustment: drive the valve stem, within the swing of about 70°, the piston can move back and forth, so that the valve is fully open and fully closed; The debugging should be sensitive, and the parts should not have any jamming and abnormal noise;
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Add：12th Floor, No. 30, Lane 160, Yinkang Road, Minhang District, Shanghai
Tel：+86 21-54736126 21-54737190
+86 21-64988573 21-64988567
Email：sales@vattenvalve.com