Selection principles and applicable occasions of butterfly valves

What is a butterfly valve?

Butterfly valve, also called flap valve, is a kind of regulating valve with simple structure. It can also be used for on-off control of low-pressure pipeline media. Butterfly valve refers to a kind of valve whose closing part (disc or butterfly plate) is a disc, which rotates around the valve shaft to achieve opening and closing. It mainly plays a role of cutting off and throttling on the pipeline. The butterfly valve opening and closing part is a disc-shaped butterfly plate, which rotates around its own axis in the valve body to achieve the purpose of opening and closing or adjustment. Butterfly valves are suitable for pipelines transporting various corrosive and non-corrosive fluid media in engineering systems such as generators, coal gas, natural gas, liquefied petroleum gas, city gas, cold and hot air, chemical smelting and power generation and environmental protection, for regulation and interception the flow of the medium.

Where the butterfly valve is applicable

Butterfly valves are suitable for flow regulation. Since the pressure loss of the butterfly valve in the pipeline is relatively large, about three times that of the gate valve, when selecting the butterfly valve, the influence of the pressure loss of the pipeline system should be fully considered, and the strength of the butterfly plate to withstand the pressure of the pipeline medium when it is closed should also be considered sex. In addition, it is necessary to consider the limitation of the working temperature of the elastic valve seat material at high temperature.
The structural length and overall height of the butterfly valve are small, the opening and closing speed is fast, and it has good fluid control characteristics. The structural principle of the butterfly valve is most suitable for making large-diameter valves. When a butterfly valve is required to control flow, the most important thing is to correctly select the size and type of the butterfly valve so that it can work properly and effectively.
Generally, in throttling, regulating control and mud medium, short structure length and fast opening and closing speed (1/4r) are required. Low pressure cut-off (small pressure difference), butterfly valve is recommended.
In the case of two-position adjustment, narrowed passage, low noise, cavitation and vaporization, a small amount of leakage to the atmosphere, and abrasive media, butterfly valves can be used.
When using butterfly valve under special conditions such as throttling adjustment, strict sealing or severe wear, low temperature (cryogenic) and other operating conditions, a special design for triple eccentric or double eccentric with a specially designed metal seal with adjusting device is required Butterfly valve.
The center line butterfly valve is suitable for fresh water, sewage, sea water, salt water, steam, natural gas, food, medicine, oil and various products that require complete sealing, zero gas test leakage, high life requirements, and working temperature of -10~150℃ Acid-base and other pipelines.
The soft-sealed eccentric butterfly valve is suitable for the two-way opening and closing and adjustment of ventilation and dust removal pipelines. It is widely used in gas pipelines and waterways in metallurgy, light industry, electric power, and petrochemical systems.
The metal-to-metal wire sealing double eccentric butterfly valve is suitable for urban heating, steam, water and gas, oil, acid and alkali pipelines, as a regulating and intercepting device.
In addition to being used as a large-scale pressure swing adsorption (PSA) gas separation device program control valve, the metal-to-metal seal triple eccentric butterfly valve can also be widely used in petroleum, petrochemical, chemical, metallurgy, electric power and other fields. It is a gate valve, stop valve, etc. Good alternative product.

Selection principle of butterfly valve

  • 1. Since the butterfly valve has a relatively large pressure loss compared to the gate valve, it is suitable for piping systems with less stringent pressure loss requirements.
  • 2. Since the butterfly valve can be used for flow adjustment, it is suitable for selection in pipelines that require flow adjustment.
  • 3. Due to the limitation of the structure of the butterfly valve and the sealing material, it is not suitable for high temperature and high pressure pipeline system. Generally, the working temperature is below 300℃, and the nominal pressure is below PN40.
  • 4. Since the structure length of the butterfly valve is relatively short and can be made into a large diameter, it is appropriate to choose a butterfly valve in the occasions where the structure length is required to be short or a large diameter valve (such as DN1000 or more).
  • 5. Since the butterfly valve can be opened or closed by only rotating 90°, the butterfly valve should be used in the occasions requiring fast opening and closing.

DN50-DN400 butterfly valve structure size drawing and data sheet:

1 1P13116305G00 - Selection principles and applicable occasions of butterfly valves

Specification
ΦD1
n-Φ
ΦD2
ΦD3
L
H
H1
H2
L1
L2
B-f
Φd
mm
in
PN10
PN16
PN10
PN16
PN10
PN16
DN50
2″
125 
4-18
165
102
108
203
120
65
195
165
20-3
145
DN65
2.5″
145 
4-18
185
122
112
223
130
65
195
165
20-3
145
DN80
3″
160
4-18
8-18
200
132
114
245
145
65
195
165
22-3
145
DN100
4″
180
8-18
220
158
127
269
155
65
195
165
24-3
145
DN125
5″
210 
8-18
250
184
140
295
170
65
195
165
26-3
145
DN150
6″
240
8-22
285
212
140
333
190
65
195
165
26-3
145
DN200
8″
295
8-22
12-22
340
268
152
375
205
80
287
270
26-3
280
DN250
10″
350
355
12-22
12-26
395
405
320
165
433
235
80
287
270
28-3
280
DN300
12″
400
410
12-22
12-26
445
460
370
178
503
280
80
300
380
28-4
280
DN350
14″
460
470
16-22
16-26
505
520
430
190
589
310
80
300
380
30-4
280
DN400
16″
515
525
16-26
16-30
565
580
482
216
640
340
103
450
450
32-4
400

Structure size drawing and data sheet of large diameter DN450-DN1000 butterfly valve

1 1P131163I0207 - Selection principles and applicable occasions of butterfly valves

Specification
ΦD1
n-Φ
ΦD2
ΦD3
L
H
H1
H2
L1
L2
B-f
Φd
mm
in
PN10
PN16
PN10
PN16
PN10
PN16
DN450
18″
565
585
20-26
20-30
615
640
545
222
720
375
172
480
490
32-4
300
DN500
20″
620
650
20-26
20-33
670
715
609
229
785
430
172
480
490
34-4
300
DN600
24″
725
770
20-30
20-37
780
840
720
267
910
500
210
480
490
36-5
300
DN700
28″
840
24-30
24-37
895
910
800
292
1038
560
290
640
660
40-5
400
DN800
32″
950
24-34
24-40
1015
1025
905
318
1149
620
290
640
660
44-5
400
DN900
36″
1050
28-34
28-40
1115
1125
1001
330
1249
665
360
750
860
46-5
300
DN1000
40″
1160
1170
28-37
28-43
1230
1255
1112
410
1392
735
410
850
900
46-5
300

Precautions for butterfly valve installation

  • 1. The pipe clamp flange standard must conform to the butterfly valve standard;
  • 2. Before use and installation, check whether the use conditions are consistent with the performance of the butterfly valve;
  • 3. Clean the inner cavity and sealing surface of the valve before installation to prevent dirt and debris from adhering;
  • 4. Both ends of the valve seat protrude from the end face of the valve body as flange sealing gaskets, no need to add sealing gaskets when installing the butterfly valve;
  • 5. This butterfly valve can be installed on horizontal, vertical and any angle pipeline, and can be used in two directions;
  • 6. The butterfly valve must not be installed at the corner of the pipeline, and it is not allowed to install it upside down;
  • 7. The butterfly valve must be in the closed position during installation to ensure that the butterfly plate does not collide with the pipe flange, etc.;
  • 8. Confirm that the flange welding is correct. After the butterfly valve is installed, it is not allowed to re-weld the flange to avoid scalding the rubber parts and the anti-corrosion coating;
  • 9. If the butterfly valve opens and closes abnormally, the cause should be found out, the fault should be eliminated, and methods such as knocking, smashing, prying, handle extension arm and other methods should not be used to forcibly open and close.

Source: China Butterfly 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
selection principles and applicable occasions of butterfly valves - Selection principles and applicable occasions of butterfly valves
Article Name
Selection principles and applicable occasions of butterfly valves
Description
The structural length and overall height of the butterfly valve are small, the opening and closing speed is fast, and it has good fluid control characteristics. The structural principle of the butterfly valve is most suitable for making large-diameter valves. When the butterfly valve is required to control flow, the most important thing is to correctly select the size and type of the butterfly valve so that it can work properly and effectively.
Author
Publisher Name
www.steeljrv.com
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