What is a valve? A valve is a device that regulates the flow of a liquid by opening or closing or partially obstructing the flow in its pathway. They are used in many appliances where unidirectional flow needs to be achieved and the flow from opposite direction could be prevented.
What is a gate valve?
The gate valve is a type of valve that is widely used in pipelines. A gate valve has a variety of functions when fitted in a pipeline but its main role is to connect and shut off the medium. The gate valve mechanism doesn’t have much effect on regulating the flow of the liquid, after it can completely get connected or shut off the medium. Due to its property, the gate valve has found many applications across a wide range of devices. Be it a pressure application, the gate valve could be used. Or it can also be used in an application where pressure and calibre are involved. That’s why it has a much wider range of applications than the other types of valves.
When are they used?
These valves are often used when there is a requirement of minimum pressure loss and the free bore is required. As it has been already mentioned above, the gate valve operates via connecting or shutting off the medium. When the gate valve is opened fully, the valve connects the medium and there is no obstruction in place. This, in turn, results in very less amount of pressure loss. The gate valves are used in a wide range of devices which are associated with pipelines supplying water, gas etc.
Types of gate valves:
Based on numerous aspects, one can choose gate valves from a variety of options. But all these can be divided into two main categories. One is parallel gate valves and the other one is wedge-shaped gate valves. These two has a different structure and thus comes with their own set of features.
• The parallel gate valves use a flat gate in between two parallel seats. The popular type of gate valve is also of the parallel mechanism which has a knife gate valve as well. The knife gate valve is designed with a sharp edge at the bottom of the gate
• In contrast to parallel gate valves, the wedge-shaped gate valves have two inclined seats whereas, in the case of parallel gate valves, the two seats are parallel in nature. The wedge-shaped gate valve is crafted with a slightly mismatched inclined gate to suit the purpose best.
Advantages of gate valves:
The advantages of gate valves multiply the usage of gate valves in the field of pipelines. They are used in water supply, gas supply etc. The gate valves are useful in connecting and shutting off the medium and this property of the gate valve gives them the advantage. Another aspect of the gate valve is, these valves are often used when there is a need to minimize pressure loss and the free bore is required. Here are the few of the advantages that the gate valves hold above others.
• As it has been already said, the resistance that is offered by the gate valve is very small. This minimum pressure loss property makes it a suitable candidate for the processess where there is a requirement of minimum loss of pressure. The loss of pressure is minimum in case of gate valve because the body of the valve is a straight one and no change of direction takes place in the valve. Had there been a change in the course of the medium, there would have been a loss of pressure as the change in course can lead to a loss of pressure. But in the case of gate valve, there is no such change in the course and this makes gate valves most fitting for the circumstances where there is a requirement of minimum loss of the amount of pressure.
• The gate valve works through the connecting and shutting of the medium. The performance of any valve depends on the sealing mechanism. A better sealing mechanism leads to a better performance of the valve. The sealing mechanism of the gate valve is much better than those of other valves and hence, the gate valve is widely used in different fields. The opening and closing mechanism of the gate valve is also more convenient in case of gate valve than the other types of valves.
• Due to the property of less amount of pressure loss and connecting and shutting off the medium, the gate valve is also used in various types of applications. For example, excluding steam, oil and another medium, it is also used in the flow of granular solid which has a large viscosity. The gate valve could also be used as venting valve and low vacuum system valve. Due to this wide range of properties for which, the gate valves are especially used in different types of circumstances and they are getting more and more roles in different fields.
Disadvantages of gate vales:
With all the advantages in place, the gate valve also has some disadvantages also. These disadvantages may include:
• The opening and closing time of the gate valve is too long and hence, in some cases where the valves do need to operate in a swift manner, the gate valves fails to serve that purpose. The prolonged opening and closing time also make it unsuitable for the flows where you need to connect and shut the medium off immediately.
• Though the sealing mechanism of the gate valve is much better than any other types of valves, due to being itself prone to scratch, over the time, the gate valve may lose its efficiency. There will be friction between the plate of the valve and the two-sealing surface and over the course of time, it will lead to wear and tear. Thus, the sealing mechanism will fail to work at optimal performance.
Despite certain major drawbacks, gate valves have a number of considerable advantages.