What occasions are open rod gate valves and dark rod gate valves suitable for?

The difference between open rod gate valve and dark rod gate valve:

1. The open rod gate valve can see the screw rod, but the dark rod can not see the lead screw;

2. The open rod gate valve is used to lift or lower the valve disc through the threaded transmission between the valve stem and the steering wheel; When the dark rod gate valve is switched, the steering wheel and the valve stem are connected together and relatively immovable, and it is driven by the valve stem to rotate at the fixed point to drive the valve disc to lift up and down to complete the opening and closing;

3. The transmission thread of the dark rod gate valve is located inside the valve body, and in the process of opening and closing, the valve stem only rotates, and the gate plate rises and falls in the valve body; The valve stem of the open rod gate valve drives the gate plate to rise and fall together, and the transmission thread on the valve stem is outside the valve body, and the opening and closing and position of the gate can be intuitively judged according to the movement direction and position of the valve stem;

4. The height of the dark rod gate valve is small; Exposed rod gate valves require a large installation space;

5. The structure of the open rod gate valve is beneficial to the lubrication of the valve stem, and the degree of opening and closing is obvious; The stem thread of the dark rod gate valve not only cannot be lubricated, but also directly accepts the erosion of the medium and is easy to be damaged. Therefore, open rod gate valves are more widely used. Concealed rod gate valves are suitable for large diameters or where installation space is limited.

For valves, there are open rods and dark rods, and the differences are as follows:

1. The structure is different.

The stem nut of the valve open rod is on the valve cover or bracket, and when the gate is opened and closed, the stem nut is rotated to realize the lifting of the valve stem.

The stem nut of the valve rod is in the valve body and is in direct contact with the medium. When opening and closing the gate, it is achieved by rotating the valve stem.

2. The advantages are different.

The stem nut of the valve open rod, this structure is beneficial to the lubrication of the valve stem, and the degree of opening and closing is obvious.

The stem nut of the valve concealed rod and the height of the gate valve always remain the same, so the installation space is small. This structure should be equipped with an opening and closing indicator to indicate the degree of opening and closing. The disadvantage of this structure is that the stem thread not only cannot be lubricated, but also directly accepts the erosion of the medium and is easily damaged.

3. The applicable scenarios are different.

The stem nut of the valve open rod is used in a wide range of applications and is suitable for most scenarios.

The stem nut of the valve concealed rod is suitable for large diameter or gate valves with limited installation space.

The difference between open and dark rods.

Generally, it is used for gate valves, and the so-called open rod means that the stem head will rise and fall when opening and closing the valve. That is, you can see the movement of the valve stem (not rotating, only lifting).The so-called dark rod means that the valve stem will only rotate when opening and closing the valve, but will not rise or fall.

The open rod is the stem head that rises and falls when the valve is opened and closed. That is, you can see the movement of the valve stem (not rotating, only lifting).The so-called dark rod means that the valve stem will only rotate when opening and closing the valve, but will not rise or fall. The model of the open rod is Z44 and the model of the dark rod is Z45.

The most essential difference between the open rod and the dark rod is that the medium of the open rod is not in contact with the valve stem thread, and the dark rod is in contact, and the gate valve of the dark rod is usually used for infrequent opening and closing, and the installation space is small. That is, you can see the movement of the valve stem (not rotating, only lifting).The so-called dark rod means that the valve stem will only rotate when opening and closing the valve.

The valve of the dark rod can also be made into a situation where the stem thread is not in contact with the medium.

The simple identification method is: the dark rod is the stem nut in contact with the medium. The stem nut of the open rod does not touch.

Exposed rod globe valve.

The thread of the shut-off valve stem is on the outside of the valve body. Its advantage is that the valve stem is not eroded by the medium, which is convenient for lubrication, and this structure is more common.

Concealed rod globe valve.

The thread of the stem of the globe valve is in the valve body. The stem threads of this structure are in direct contact with the medium, are susceptible to erosion, and cannot be lubricated. This structure is used in small calibers and places where the temperature is not high.

The difference is still similar to that of open rod gate valves and dark rod gate valves. The structural forms are all low in and high out, with straight-through, DC and angular types.

1. The lifting screw of the dark rod gate valve only rotates without moving up and down, and the exposed is only a rod, and its nut is fixed on the ram, and the ram is lifted by the rotation of the screw, and there is no visible gantry; The transmission thread of the dark rod gate valve is located inside the valve body, and in the process of opening and closing, the valve stem only rotates, and the gate plate is lifted and lowered in the valve body. As a result, the height dimensions of the valve are small.

The lifting screw of the open rod gate valve is exposed, and the nut is close to the handwheel and is fixed (not rotating or axially moving), and the ram is lifted by rotating the screw, and the screw rod and the ram have only relative rotational motion and no relative axial displacement, and the appearance is a door-shaped bracket.

2. The dark rod valve is that the lead screw cannot be seen, and the open rod is the one that can see the screw rod.

3. When the dark rod valve is opened and closed, the steering wheel and the valve stem are connected together and relatively immovable, and it is through the rotation of the valve stem at the fixed point to drive the valve disc to lift up and down the gate to complete the opening and closing. Exposed rod valves raise or lower the disc through the threaded transmission between the stem and the steering wheel.

4. The valve stem of the open rod gate valve drives the gate plate to rise and fall together, and the transmission thread on the valve stem is outside the valve body, so the opening and closing and position of the gate can be intuitively judged according to the movement direction and position of the valve stem, and the transmission thread is convenient for lubrication and is not subject to fluid corrosion, but it requires a large installation space.

The first-class fire engineer examination memorizes the mantra of the bright rod gate valve and the dark rod gate valve.

Crown valve pushing.

The functionality is the same.

The only difference is.

The open rod gate valve can be opened from the appearance, whether the valve is closed or open, and the open rod is generally used for fire fighting.

It is clear whether the valve is open or closed at the first time.

The dark rod had to be tried manually.