Types of Valves Used for Standard Boilers and Their Functions
Valve or valve is a device that is installed on a piping system, which functions to regulate and direct the flow rate of the fluid by opening, closing or partially closing the fluid flow. Valves have an important role in an industry such as controlling water for the purpose of heating water in a boiler.
Valve can be operated manually, both by using the handle, pedal lever and so on. Besides being operated manually, the valve can be operated automatically using the principle of pressure and temperature. These changes will affect the diaphragm, spring or piston so that it will automatically move the valve with the system open and close.
1. Gate Valve steam boiler
Gate valve is a type of valve that is used to open the flow by lifting the closing gate which is round or rectangular. Gate Valve is a type of valve that is most often used in piping systems whose function is to open and close the flow.
The gate valve is not to adjust the rate of a fluid flow by opening half or a quarter of its position, so the gate position on this valve must be completely open (fully open) or completely closed (fully close). If the gate position is half open, turbulence will occur in the flow and this turbulence will cause:
a) There will be erosion of the gate corners.
this turbulence fluid flow rate can erode gate angles that can cause erosion and eventually the valve cannot work perfectly.
b) There is a change in the position of the closing gate holder.
The closing gate will be swinging towards the position of the seat, so that over time its position will change to the stand so that when the valve closes, the closing gate will not be in the right position, so it can cause passing.
2. Globe Valve steam boiler
Globe Valve is a type of valve that is used to regulate the flow rate of fluid in a pipe. The basic principle of a globe valve operation is the perpendicular movement of the disk from its stand. This ensures that the ring-shaped space between the disk and seat ring is gradually as close as Valve is closed.
There are three main types of Globe Valve body designs, namely: Z-body, Y-body and Angle-body:
Z-Body design is the most commonly used type, with a Z-shaped diaphragm. The position of the horizontal disk stand and movement of the disk are perpendicular to the axis of the pipe or disk holder. The symmetrical shape makes it easy to make, install or repair.
Y-Body design is an alternative to high pressure drop. The position of the disk holder and stem has a 45˚ angle from the direction of the fluid flow. This type is very suitable for high pressure
Design Angle-Body is a basic modification of Z-Valve. This type is used to transfer flow from vertical to horizontal.
The advantages of using a globe valve are:
Ability to close well.
throttling capability (adjusting flow rate) Good enough.
The main disadvantages of using globe valves are:
The pressure drop is higher than the gate valve
Large-size valves require enough power or larger actuators to operate
Butterfly Valve is a valve that can be used to isolate or regulate flow. The closing mechanism takes the form of a disk. The operating system is similar to a ball valve, which allows it to close quickly. Butterfly Valve is generally preferred because the price is cheaper than other types of valve. This valve design is lighter in weight than other valve types. Maintenance costs are usually lower because of the minimal number of moving parts.
The Butterfly Valve is easy and fast to operate because the 90o rotation is driven by the handwheel by moving the disk from fully closed to fully open position.
Butterfly Valve is perfect for handling large flows of liquids or gases at relatively low pressures and for handling large quantities of suspended solids.
4. Check Valve
Check valve is a tool used to make fluid flow only flow in one direction or to prevent reversed flow / back flow. When the fluid flow rate corresponds to its direction, the flow rate will make a plug or disk open. If there is pressure coming from the opposite direction, the plug or disk will close.
Check valve types:
a. Swing Check Valve
This type of check valve consists of a disk the size of a pipe used, and is designed to hang on the hinge at the top. If there is a forward flow or foward flow, the disk will be driven by pressure so that it can open and fluid can flow towards the outlet channel. Whereas in the event of a reverse flow, fluid pressure will push the disk to close tightly so that no fluid flows. The higher the back pressure the more tightly the disc is attached to the stand.
b. Lift Check Valve
Use for steam, gas, and liquid fluids that have high flow. In its configuration similar to a globe valve, only the globe valve rotation of the disk or valve can be manipulated while in the elevator check valve is not (because the globe valve is a type of rotary valve and control valve).
The inlet and outlet ports are separated by a cone-shaped plug located on a stand, generally made of metal. When a foward flow occurs, the plug will be driven by fluid pressure so that it escapes from the stand and fluid will flow to the outlet channel. Whereas if there is a reverse flow, the pressure of the fluda will put the plug on the stand, the greater the pressure the meeting the position of the plug in the seat is tight, so the fluid cannot flow.
the material from the plug holder is metal, this takes into account very little leakage from the check valve. Generally the lift check valve is used for gas fluid applications because of the small level of leakage. The use of this type of elevator check valve in the industry is to prevent condensate backflow to steam traps that can cause corrosion in steam turbines. The advantage of using the lift check valve is the simplicity of the design and requires little maintenance. The disadvantage is that the installation of a check valve type of lift is only suitable for large diameter horizontal pipes.
c. Back water check valve
Back water valve, widely used in underground water drainage systems that prevent backflow from drains during a flood. When the flood drain will be full and high pressure, allowing backflow to occur, by using a back water valve, this can be handled properly.
d. Swing Type Wafer Check Valve
In the use of the swing check valve and the lift check valve are limited only to large size pipes (DN80 or more diameter). so the solution is to use a wafer check valve. By using a wafer ceck valve can be used tubing with a size that cones on one side so that it can be applied to pipes that are smaller in size.
e. Disk Check valve
This type of valve consists of body, spring, spring retainer and disc. The principle works is when there is a flow flow, the disk will be driven by fluid pressure and push the spring so that there is a gap that causes fluid flow from the inlet to the outlet. Conversely if reverse flow occurs, fluid pressure will push the disk so that it closes the fluid flow
the pressure difference is needed to open and close the valve of this type and this is determined by the type of spring used. In addition to standard spring, there are also several spring options available:
No spring – Used where the pressure difference in the valve is small.
Nimonic spring – Used in high temperature applications.
Heavy duty spring – This increases the opening pressure required. When installed on a boiler water feed line, it can be used to prevent boiler steam from being flooded when they are unpressurised.
f. Split disc check valve
This type of check valve consists of a disk whose center is a shaft that allows the disk to move as if it is divided into two if driven from the right direction (foward flow) and closes tightly when pressed from the wrong direction (reverse flow).
5. Safety Valve
A safety valve is a type of valve whose mechanism automatically releases substances from a boiler, pressure vessel, or a system, when the pressure or temperature exceeds a predetermined limit.
How the Pressure Safety Valve works:
The pressure savety valve has three main parts, namely inlet, outlet and spring set. Pressurized fluid is on the PSV inlet. The PSV position closes as long as the fluid pressure is smaller than the spring pressure on the spring set. Conversely if the fluid pressure is higher than the pressure spring set then the springset will move up and open the valve which will throw pressure through the outlet until the maximum fluid pressure is equal to the pressure spring set
Strainer is a type of filter tool whose function is that when the pump sucks water, dirt or other material is not sucked into the pump which can cause pump impeller damage.