What is a plunger valve?

What is a plunger valve?

Plunger valve is composed of valve body, valve cover, valve stem, plunger, hole rack, sealing ring, handwheel and other parts. When the handwheel rotates, the valve opens and closes by driving the plunger up and down in the middle of the hole rack by the valve stem. The interference fit between the plunger and the sealing ring is adopted in the valve. By adjusting the flange bolt in the pressure cap, the lateral force produced by the compression of the sealing ring is sealed with the orifice in the valve body and the outer circle of the plunger, thus ensuring the sealing of the valve, eliminating the leakage inside and outside, and at the same time, the opening moment of the valve is small, so that the valve can be opened and closed quickly. Compared with globe valve, plunger valve has long service life and labor saving operation. But the regulating stroke is longer than the globe valve, so throttling control is more difficult than the globe valve. Neither is suitable for places with clear requirements for regulation.

20190415031026 49782 - What is a plunger valve?

Working Principle of Plunger Valve
Globe valves VS plunger valves
Characteristic of plunger valve
Types of plunger valves
Technical parameters of plunger valve
Size of Plunger valve
Use of Plunger Valve

The closure of the plunger valve consists of a stainless steel plunger, two elastic sealing rings and a metal separator. The sealing effect is achieved by the close cooperation of the plunger and the sealing ring. The plunger is inserted in two sealing rings and the sealing area is much larger than that of the ordinary globe valve. When the plunger valve is switched on and off, the plunger moves slowly in the sealing ring, and the contact surface is almost not worn out. When the plunger is closed, the plunger is inserted into the lower density. Seal ring, cut off the flow channel; when opened, although the plunger is separated from the lower seal ring, it is still hidden in the upper seal ring, keeping away from the outside world, so as not to leak.
Because the plunger surface is processed by high precision cylindrical grinder. The sealing ring adopts a new non-toxic sealing material with strong elasticity and high wear resistance, so the sealing is reliable and durable. The service life of the plunger valve is improved.

Working Principle of Plunger Valve

Plunger valve is also known as piston valve. Its opening and closing parts are driven by the valve stem, and it is a valve that moves up and down linearly along the axis of the seat (sealing ring). The performance is the same as that of the globe valve, which can also play a certain role in throttling besides being used for closing the flow.
The plunger valve is based on the radial sealing principle. It has the advantages of simple structure, flexible opening and closing, good sealing, convenient disassembly and maintenance, and long service life. In a plunger valve, when the valve is opened, the medium can begin to flow only when all the plungers leave the sealing ring. Therefore, the seat seal surface will not be damaged by fluid erosion. When the valve closes, the plunger can scrape the solid particles attached to the seat, so the plunger valve can be used for media containing suspended particles. When the seal is damaged, the plunger and seat can be replaced on site, so that a new plunger valve can be obtained without machining. Like globe valves, plunger valves can control flow well. If the flow rate needs to be adjusted sensitively, a needle-shaped lengthening section can be installed on the plunger. Plunger valves can also be used to cut off and connect fluids when they can accept the fluid resistance generated by a curved channel.
The plunger valve is simple in structure and consists of body, bonnet, plunger, stem, guide sleeve, upper and lower sealing rings, stem nut and handwheel.
When the handwheel is rotated, the valve stem drives the plunger to and fro in the upper and lower sealing rings to complete the opening and closing of the valve. A proper interference fit is adopted between plunger and sealing ring, sealing ring and valve body. By adjusting the pressure of fixed bolt on valve cover, the sealing ring is compressed. The inner ring is tightly “clinging” to the outer fitting surface of plunger and the outer ring is tightly attached to the inner fitting surface of valve body. Thus, the radial force generated on the sealing ring is greater than the fluid pressure, thus ensuring the sealing performance.
Because the non-metallic sealing ring uses non-toxic new sealing material with strong resilience and high wear resistance, the sealing is reliable and durable. Metal sealed plunger valve is welded with alloy steel or cemented carbide on the conical surface of the valve seat, so the service performance range of the valve is improved comprehensively.
Structural characteristics of plunger valve
The plunger valve is simple in structure and consists of body, bonnet, plunger, stem, guide sleeve, upper and lower sealing rings, stem nut and handwheel.

Compared with globe valves, plunger valves have the following advantages:

  • (1) The sealing pair of plunger valve is composed of metal and non-metal, and the specific pressure of the seal is small, so it is easy to meet the sealing requirements.
  • (2) The specific pressure of the seal depends on the interference between the seals, and the specific pressure of the seal can be adjusted by the cover bolt.
  • (3) It is not easy to accumulate impurities in the medium at the sealing surface, which can ensure the sealing performance.
  • (4) Seals are made of wear-resistant materials and have longer service life than globe valves.

Easy maintenance, in addition to replacing the sealing ring when necessary, unlike globe valves, the valve disc and seat need not be grinded.

Characteristic of plunger valve

Plunger valve has good sealing performance, compact structure, flexible and open the door, long service life and convenient maintenance; but relatively high prices.
The standard selection of plunger valve:

  • Requirements for use in high requirements for sealing;
  • In the use of water, steam, oil (UJ41W-16 (25) C) nitric acid, acetic acid and other media (UJ41W-16 (25) P/R).

The scope of application of the plunger valve

Plunger valve series valve The product is suitable for electric power, metallurgy, chemical industry, oil refining, chemical, textile, light industry, food industry, pressure is less than 16-25kgf/cm2, the temperature of water, steam, oil pipe below 250 DEG C as the opening and closing device of medium flow, but also can be used as the flow regulation.

Types of plunger valves

Plunger valves can be divided into metal and non-metal sealing plunger valves according to sealing materials. According to the structure, it can be divided into two categories: disc balanced and disc unbalanced. Disc unbalanced can be divided into straight-through plunger valve, three-way plunger valve, angle plunger valve, direct-current plunger valve and Z-channel plunger valve. Disc balanced can be divided into direct-current valve disc balanced plunger valve and angle valve balanced plunger valve.
1. Metal sealed plunger valve
The sealing pair of the metal sealed plunger valve consists of the plunger after precision grinding and polishing and the hard seat surface after surfacing.
2. Non-metallic sealed plunger valve
The performance characteristics of non-metallic sealed plunger valve are as follows:
The sealing pair of non-metallic sealed plunger valve consists of upper and lower two soft sealing rings and plunger. When the plunger is in the inner hole of the sealing ring, the sealing ring around the plunger is compressed by the load applied on the valve cover by the cover nut, thus ensuring the sealing. When the valve is opened and the plunger is withdrawn, the material of the sealing ring restores its original state under the elastic action. The plunger is connected with the valve stem after precision grinding and polishing. Sealing ring uses new non-toxic non-metallic materials, which has the functions of pressure resistance, wear resistance and self-lubrication. It has good sealing performance and long service life.
(1) Good sealing
The sealing pair of the plunger valve consists of a stainless steel plunger, two elastic sealing rings and a metal support ring which can keep the fixed distance between the upper and lower sealing rings. The plunger, like a bottle stopper, is inserted into two sealing rings. The sealing force between valve body and sealing ring, plunger and sealing ring is provided by fasteners connecting valve body and valve cover, which keep them close to each other and form bottle plug effect.
In plunger valve, the contact surface between plunger and sealing ring is cylindrical, and its sealing surface area is large. Because the sealing rings used in plunger valves have the advantages of good resilience, high strength, small coefficient of thermal expansion and good self-lubrication, the sealing performance of plunger valves is greatly improved.
In addition, during the working process of the plunger valve, the plunger is in the upper seal ring. The upward and downward reciprocating motion of the plunger is guided by the upper seal ring, which ensures that the sealing surface is uniform in force and stable in operation, and will not cause leakage due to improper use of the operator to damage the sealing surface.
(2) Wear resistance
When closing the plunger valve, the stem drives the plunger plug sealing ring, just like plugging the bottle plug into the bottle mouth. No matter how much force is exerted to rotate the handwheel, the sealing force between the plunger and the sealing ring will not be affected. The degree of pre-tightening during assembly is still maintained between them, that is, the working surface of the piston valve is not affected by external factors. When opening and closing the plunger valve, the plunger moves slowly in the sealing ring, and the contact surface between the plunger and the sealing ring hardly wears.
Fine impurities in the fluid do not damage the plunger valve. When the valve is closed, the plunger enters the sealing ring and scrapes the suspended particles from the fluid attached to the inner surface of the sealing ring.

(3) Convenient disassembly and maintenance

There is a certain adjustment gap between the valve body and the cover of the plunger valve. Once the seal ring is worn and there is a gap between the seal ring and the plunger mating surface which causes leakage, only the valve is in the closed state, and then tighten the nut on the cover slightly to make the seal ring compress and deform again, and re-tighten the outside mating surface of the plunger, it can continue to use. When the clearance is adjusted to zero, the sealing ring is replaced, which can greatly reduce the maintenance time and workload.
Because of the different material and thermal expansion coefficient between the sealing ring and the valve body and plunger, the plunger valve will cause instantaneous leakage in the alternating cold and hot parts. But on the whole, the plunger valve has flexible opening and closing, good sealing effect and convenient maintenance and disassembly, which is very suitable in actual production.
(4) Easy to open and close, flexible to operate.
The sealing ring material selected by the plunger valve has the advantages of small thermal expansion coefficient, good self-lubrication, high strength, small friction coefficient, acid-alkali resistance, and not easy to aging. In addition, the contact surface roughness of the sealing parts is higher, so the closing force of the plunger valve is only slightly greater than the medium pressure, so the opening and closing of the plunger valve is convenient and flexible.

Technical parameters of plunger valve

Name UJ41H-16C performance specification: UJ41H (Y) -25 performance specification:
Nominal pressure (PN): 1.6Mpa 2.5-4Mpa
Low pressure seal test pressure: 0.6Mpa 0.6Mpa
Strength test pressure (PT): 2.4Mpa 3.75-6Mpa
Applicable medium: Steam, water, oil Steam, water, oil

Connection, main structure size of plunger valve

20190415030042 66353 - What is a plunger valve?


DN (mm)
The size (mm)
UJ41H-16C, Y, P, R
Fifteen Twenty Twenty-five Thirty-two Forty Fifty Sixty-five Eighty One hundred One hundred and twenty-five One hundred and fifty Two hundred Two hundred and fifty Three hundred Three hundred and fifty Four hundred
L One hundred and thirty One hundred and fifty One hundred and sixty One hundred and eighty Two hundred Two hundred and thirty Two hundred and ninety Three hundred and ten Three hundred and fifty Four hundred Four hundred and eighty Four hundred and ninety-five Six hundred and twenty-two Six hundred and ninety-eight Seven hundred and eighty-seven Nine hundred and fourteen
H One hundred and seventy One hundred and ninety Two hundred and ten Two hundred and fifty Two hundred and seventy Three hundred Three hundred and forty Three hundred and eighty Four hundred and twenty Four hundred and fifty Five hundred and forty Six hundred and forty Seven hundred and forty Eight hundred and fifty Nine hundred and seventy One thousand and one hundred
W One hundred One hundred One hundred and twenty One hundred and forty One hundred and sixty One hundred and eighty Two hundred Two hundred and forty Two hundred and seventy Three hundred and ten Three hundred and forty Four hundred Five hundred and twenty Six hundred and forty Seven hundred and sixty Nine hundred
D Ninety-five One hundred and five One hundred and fifteen One hundred and thirty-five One hundred and forty-five One hundred and sixty One hundred and eighty One hundred and ninety-five Two hundred and fifteen Two hundred and forty-five Two hundred and eighty Three hundred and thirty-five Four hundred and five Four hundred and sixty Five hundred and twenty Five hundred and eighty
K Sixty-five Seventy-five Eighty-five One hundred One hundred and ten One hundred and twenty-five One hundred and forty-five One hundred and sixty One hundred and eighty Two hundred and ten Two hundred and forty Two hundred and ninety-five Three hundred and fifty-five Four hundred and ten Four hundred and seventy Five hundred and twenty-five
D1 Forty-five Fifty-five Sixty-five Seventy-eight Eighty-five One hundred One hundred and twenty One hundred and thirty-five One hundred and fifty-five One hundred and eighty-five Two hundred and ten Two hundred and sixty-five Three hundred and twenty Three hundred and seventy-five Four hundred and thirty-five Four hundred and eighty-five
T Fourteen Fourteen Fourteen Sixteen Sixteen Sixteen Eighteen Twenty Twenty Twenty-two Twenty-four Twenty-six Thirty Thirty Thirty-four Thirty-six
N-. 4-14 4-14 4-18 4-18 4-18 4-18 4-18 8-18 8-18 8-18 8-23 12-23 12-25 12-25 16-25 16-30
Weight (Qian Ke) Three point five Four point five Five point five Eight Eleven point five Fifteen Twenty-one Thirty Forty-two Fifty-five Ninety One hundred and forty-two Two hundred and ten Two hundred and ninety Five hundred  

Cautions for Use of Plunger Valve

Plunger valve is composed of valve body, valve cover, valve stem, plunger, hole rack, sealing ring, handwheel and other parts. The following points should be paid attention to when using:
The opening and closing direction of plunger valve should be clockwise closed.
The plunger valve in the pipe network is manual opening and closing. The opening and closing speed should not be too much. The large caliber plunger valve should also be within 200-600 revolutions.
In order to facilitate one person’s opening and closing operation, the maximum opening and closing moment should be 240N-m under the condition of pipeline working pressure.
The opening and closing end of the plunger valve shall be square tenon with standardized size and face to the ground. The solenoid valve with wheel disc is not suitable for underground pipeline network.

Display panel for opening and closing degree of plunger valve

The scale line of valve opening and closing degree should be cast on the cover of gearbox or on the shell of the display disk after changing direction, all facing the ground, and the scale line should be brushed with phosphor to show striking.
The material of the indicator needle can be made of stainless steel solenoid valve steel plate under better management. Otherwise, it is painted steel plate. Aluminum sheet should not be used.
The indicator needle is eye-catching and firmly fixed. Once the electric regulating valve is opened and closed accurately, it should be locked by rivet.
If the plunger valve is deeply buried and the distance between the operating mechanism and the display plate and the ground is more than 1.5m, the plunger valve should be equipped with a lengthening rod device, which is fixed firmly so that people can observe and operate from the ground. That is to say, the operation of opening and closing diaphragm pump in pipeline network is not suitable for downhole operation.

Source: China Plunger Valves Manufacturer – Yaang Pipe Industry Co., Limited (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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Summary
what is a plunger valve - What is a plunger valve?
Article Name
What is a plunger valve?
Description
Plunger valve is composed of valve body, valve cover, valve stem, plunger, hole rack, sealing ring, handwheel and other parts.
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www.steeljrv.com
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