Types Of Safety Values that you should know..

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A safety valve is a device used in many different areas of mechanical engineering and industrial processes. It is generally known as a relief valve (analogous to a float switch) and used in emergency rescue services. The main difference with their operation principle: the safety valve relieves the hydraulic pressure in the system (from the boiler), it is often a pressure relief device for fluid vessels and when the set limit value is reached then the valve reverses almost completely. This action prevents an explosion from taking place. In a steam turbine the pressure will rise when pressure is low and lower when the pressure is high.

In this article we shall discuss about the working principle of a safety valve. The principle is quite similar to that of a spring that is used to stop a piston or the shaft rotating. In case of a safety valve the principle is the same. The difference is that a safety valve uses an electric motor to raise or lower the set pressure. For the purpose of explanation we assume that the boiler is operating at normal level.


There are many different varieties of safety valves available. They are available in different sizes such as NPT, PT, SMT, GPM and GSH. The most common types are NPT and SMT. The characteristics of these varieties are discussed in below.


NPT safety valves are available in both closed and open styles. In closed style they have a cover which is located above the boiler area. The cover has an adjustable flap and a valve seat. This arrangement enables you to regulate the shut off pressure and the curtain area. This is suitable if the pressure is very high and you need to shut down the boiler before it causes any damage to your equipment.


On the other hand, the safety valve known as PT is positioned on the opposite side of the main cylinder. It prevents the pressure from increasing automatically as it controls the amount of air inlet. PT safety valve works in the similar manner as the SMT variety but is placed opposite to the hot water cylinder. In this type of safety valve there is a relief valve which shuts down the hot water system automatically when there is a drop in the static pressure. The most important advantage of PT safety valve is that it provides pressure protection against the shock hazard.


SMT safety valves are often installed with steam engines. In such cases, the steam pressure is high and the boiler cannot handle the high pressure. In order to prevent the boiler from being damaged, the manufacturers install safety valves which are designed to regulate the steam pressure. The most common variety for SMT safety valves is the open top variety. This type features a relief valve which comes in the form of a rectangular cover.


The open top safety valve is one of the most commonly installed safety valves and can be found in residential and commercial applications. The safety relief valve which comes as a rectangular cover is located between the ball and cover cylinder and acts as a safety valve for high fluid pressure. This type of safety valve has been used since the 1950s.


As discussed above, the variation in the types of safety valve available makes it impossible to generalize the operation of all safety relief valves. Each application will have its own unique set of circumstances which will necessitate a specific design. When using a safety valve for high pressure situations, it is very important to make sure that there is not excessive buildup of static pressure or excessive reduction in fluid pressure. In such cases, you should ensure that the setting of your safety valve is appropriate for the application.

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