In one of my earlier videos, I explained how you can generate 20 control valves data sheets within one minute through ProMax. In this video, I will further explain how you can complete all the mechanical details so that they are ready to send out for quote.
As I explained in my previous video, it is very easy to import process data into the service conditions section in this excel spread sheet. We fill out two control valves process data in seconds. Let us focus on this level control valve LV-400.
There are totally nine (9) mechanical data sections in a standard ISA valve data sheet, Service conditions, Line, Valve body, Trim, Actuator, Positional, Switches, Instrument Air and Test section.
In the line section, you need to input the inlet and outlet pipe diameter. If you know the pipe schedule, you can put it there as well. If the normal operating temperature is higher than 150 F or lower than 32 F, you probably want to put the insulation.
Generally speaking, three valve types are used for control valve. Most of the time, the control valve type is Globe. You can also select ball or butterfly type if you are sure. Valve size is typically one size smaller than the pipe size, but we will let the valve vendor to confirm. For the Max pressure/temperature, you can simply input the design pressure and temperature of the valve upstream equipment. Valve body is normally carbon steel, but it can be stainless steel for cryogenic conditions. Valves are normally connected to the pipes through the raised face flange to prevent leakage. In addition, you also need to specify the flange class.
Now let's move to the Trim section. There are three kinds of Characteristics, equal percentage, linear and quick opening. Equal percentage is most popular for most cases. Linear valves are primarily used for liquid level control, while quick opening valves are primarily used for ON and Off valves. In addition, the trim can be either balanced or unbalanced. Balanced valves gives smaller actuator, but more expense.
Regarding the Actuator type, it can be either pneumatic, hydraulic or motor driven. Most of the time, the valve is driven pneumatically by instrument air. Control valves are modulating valves. Instrument air pressure is normally within 70 to 120 psig range. Actuator is normally parallel to pipe to reduce piping interference. Hand wheel is not normally necessary. When instrument air fails, the valve can either fail open or close. Normally the input signal is 4 to 20 mini amps, where 4 mini amps means valve is closed.
Positioner can be either a I/P type or P/P type. With the I/P type, the positioner converts the 4 to 20 mini amps signal into the valve position and the pressure to operate the actuator. P/P type translates the input pressure into another pressure to operate the actuator to arrive the desired position. Sometimes you might want to include a pressure gauge.
Switches are normally for ON/OFF ESD valves.
With dirty instrument air, you might want to have an air filter, in addition, a pressure gauge is preferred to regulate the instrument air supply pressure.
For a control valve, Class IV leakage should be sufficient for most cases.
Put down today's date and your name. Congratulations, this valve is ready to sent out for quote.
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For those who can't see the embedded video in this blog, please watch this video on youtube.com at http://youtu.be/2bYJcb148G4
For those who can't see the embedded video in this blog, please watch this video on youtube.com at http://youtu.be/2bYJcb148G4
