For example, if you want to open a DN100, PN10 butterfly valve, the torque value is 35NM, and the handle length is 20cm (0.2m), then the required force is 170N, which is equivalent to 17kg.
The butterfly valve is a valve that can be opened and closed by turning the valve plate 1/4 turn, and the number of turns the handle is also 1/4 turn. Then the time required to open or close is determined by torque. The greater the torque, the slower the valve opens and closes. vice versa.
2. Worm gear actuated butterfly valve:
equipped on butterfly valves with DN≥50. A concept that affects the number of turns and speed of the worm gear butterfly valve is called "speed ratio".
The speed ratio refers to the ratio between the rotation of the actuator output shaft (handwheel) and the rotation of the butterfly valve plate. For example, the speed ratio of the DN100 turbine butterfly valve is 24:1, which means that the handwheel on the turbine box rotates 24 times and the butterfly plate rotates 1 circle (360°). However, the maximum opening angle of the butterfly plate is 90°, which is 1/4 circle. Therefore, the handwheel on the turbine box needs to be turned 6 times. In other words, 24:1 means that you only need to turn the handwheel of the turbine butterfly valve 6 turns to complete the opening or closing of the butterfly valve.
| DN | 50-150 | 200-250 | 300-350 | 400-450 |
| Reduce Rate | 24:1 | 30:1 | 50:1 | 80:1 |
“The bravest” is the most popular and touching movie in 2023. There is a detail that firefighters entered the center of the fire and manually turned 8,000 turns to close the valve. People who don't know the details may say "this is too exaggerated." In fact, the firefighter inspired the story “The bravest” in the story " turned the valve 80,000 turns, 6 hours before closing it.
Don’t be shocked by that number, in the movie it’s a gate valve, but today we’re talking about a butterfly valve. The number of revolutions required to close a butterfly valve of the same DN definitely does not need to be that many.
In short, the number of opening and closing turns and action time of the butterfly valve depend on many factors, such as the type of actuator, medium flow rate and pressure, etc., and need to be selected and adjusted according to the actual situation.
Before discussing the number of turns required to close a butterfly valve, let's first understand the tool needed to open a butterfly valve: the actuator. Different actuators have different numbers of turns used to close the butterfly valve, and the time required is also different.
Butterfly valve opening and closing time calculation formula The opening and closing time of the butterfly valve refers to the time it takes for the butterfly valve to complete from fully open to fully closed or from fully closed to fully open. The opening and closing time of the butterfly valve is related to the action speed of the actuator, fluid pressure and other factors.
t=(90/ω)*60,
Among them, t is the opening and closing time, 90 is the rotation angle of the butterfly valve, and ω is the angular velocity of the butterfly valve.
1. Handle operated butterfly valve:
Generally equipped on butterfly valves with DN ≤ 200 (the maximum size can be DN 300). At this point, we have to mention a concept called "torque".
Torque refers to the amount of force required to open or close a valve. This torque is affected by a variety of factors, including the size of the butterfly valve, the pressure and characteristics of the media, and friction within the valve assembly. Torque values are usually expressed in Newton meters (Nm).
|
Model |
Pressure for Butterfly Valve |
||
|
DN |
PN6 |
PN10 |
PN16 |
|
Torque,Nm |
|||
|
50 |
8 |
9 |
11 |
|
65 |
13 |
15 |
18 |
|
80 |
20 |
23 |
27 |
|
100 |
32 |
35 |
45 |
|
125 |
51 |
60 |
70 |
|
150 |
82 |
100 |
110 |
|
200 |
140 |
168 |
220 |
|
250 |
230 |
280 |
380 |
|
300 |
320 |
360 |
500 |
3. Electric actuated butterfly valve:
Equipped with DN50-DN3000. The type suitable for butterfly valves is a quarter-turn electric device (rotating angle 360 degrees). The important parameter is torque, and the unit is N.m.
The closing time of the electric butterfly valve is adjustable, depending on the power, load, speed, etc. of the actuator, and is generally no more than 30 seconds.
So how many turns does it take to close a butterfly valve? The opening and closing time of the butterfly valve depends on the motor speed. The output speed of the ZFA valve for ordinary electric equipment is 12/18/24/30/36/42/48/60 (R/min).
For example, if an electric head with a rotational speed of 18, and a closing time of 20 seconds, then the number of turns it closes is 6.
|
TYPE |
SPEC |
Output Torque N. m |
Output Rotating speed r/min |
Working Time |
Max Diamter of Stem |
Handwheel turns |
|
|
ZFA-QT1 |
QT06 |
60 |
0.86 |
17.5 |
22 |
8.5 |
|
|
QT09 |
90 |
||||||
|
ZFA-QT2 |
QT15 |
150 |
0.73/1.5 |
20/10 |
22 |
10.5 |
|
|
QT20 |
200 |
32 |
|||||
|
ZFA-QT3 |
QT30 |
300 |
0.57/1.2 |
26/13 |
32 |
12.8 |
|
|
QT40 |
400 |
||||||
|
QT50 |
500 |
||||||
|
QT60 |
600 |
14.5 |
|||||
|
ZFA-QT4 |
QT80 |
800 |
0.57/1.2 |
26/13 |
32 |
||
|
QT100 |
1000 |
Warm reminder: The electric switch of the valve requires torque to act on it. If the torque is small, it may not be able to open or close, so it is better to choose a large one than a small one.