Nominal size and nominal pressure valves are classified according to structural principles

Nominal size and nominal pressure valves are classified according to structural principles

Nominal size DN is the numerical dimension of all piping accessories in a piping system to distinguish those parts indicated by thread or outer diameter. Nominal diameter is a rounded number used as a reference and is not identical to the machining size. PN is a numerical symbol associated with pressure. It is a convenient round number for reference. All pipe fittings with the same nominal diameter DN indicated by the same nominal pressure P and value shall have the same connection size corresponding to the end connection type.
Nominal diameter
Nominal size DN is the numerical dimension of all piping accessories in a piping system to distinguish those parts indicated by thread or outer diameter. Nominal diameter is a rounded number used as a reference and is not identical to the machining size.
Nominal sizes are marked with the letter “DN” followed by a numeric mark. If the nominal diameter is 250mm, it should be marked as DN250. Nominal size series of valves are specified in Table 1-44.
Table 1-44 Valve nominal Size series (GB/T1047-1995) (mm)
Note: bold characters in the table are commonly used nominal sizes.
Nominal pressure
PN is a numerical symbol associated with pressure. It is a convenient round number for reference. All pipe fittings with the same nominal diameter DN indicated by the same nominal pressure P and value shall have the same connection size corresponding to the end connection type.
In China, when the nominal pressure is involved, for the sake of clarity, the unit of measurement is usually given as “MPa”.
In Britain, the United States and other countries, although the concept of nominal pressure has been included in the relevant standards, but the actual use of the British system is still the >
There is a “K” grade system in Japanese standards, such as 10K,20K,40K, etc. The concept of pressure level is the same as the pressure level system in the British system, but the unit of measurement is metric. The relationship between “K “level and pressure level is shown in Table 1-46.
Nominal pressure series of valves are shown in Table 1-47
Table 1-45 >
Table 1-46 “K” class and >
Table 1-47 Nominal pressure series of valves
(GB/T1048 1990)
Valves are divided into gate valve, butterfly valve, rotary valve, globe valve, check valve, safety valve, pressure reducing valve, steam trap, diaphragm valve, multi-purpose valve and so on. Gate valves can be divided into wedge gate valves, lifting rod gate valves, rotary rod gate valves, fast opening and closing gate valves, shrink gate valves and other valves, see the table below for details.
Valves are classified according to structural principles
Valves are divided into: gate valve, butterfly valve, rotary valve, globe valve, check valve, safety valve, pressure reducing valve, steam trap, diaphragm valve, multi-purpose valve and so on. Gate valves can be divided into wedge gate valves, lifting rod gate valves, rotary rod gate valves, fast opening and closing gate valves, shrink gate valves and other valves, see the table below for details.
Single disc gate valve gate wedge gate valve gate valve flexible disc gate lifting lever gate valve rotating lever gate valve rapid opening and closing valve reducing gate valve gate valve parallel veneer parallel type lifting lever lifting lever with flow guide hole without diversion hole rotating rod with diversion holes parallel to the rotating rod no diversion Kong Shuang plate lifting lever lifting lever with flow guide hole without diversion hole rotating rod rotating rod with flow guide hole without diversion hole butterfly valve Center line butterfly valve eccentric butterfly valve single eccentric butterfly valve double eccentric butterfly valve triple eccentric butterfly valve rotary valve floating ball valve fixed ball valve Elastic ball valve cock valve pressure balance type plug valve tight type plug valve packing type plug valve self-sealing plug valve oil seal type plug valve globe valve Top threaded stem globe valve Bottom threaded stem Globe valve Straight-through globe valve Angle globe valve Three-way globe valve straight-flow globe valve plunger globe valve needle globe valve check valve Swing check valve single swing check valve double disc swing check valve lift check valve at the end of valve spring load lift check valve spring load circular disc lift check valve annular flow more shuttle lift check valve check valve butterfly check valve veneer butterfly check valve pipeline double plate butterfly check valve check valve nozzle type check valve air exhaust check valve slow close check valve diaphragm type check valve cone Circular knitting film type check valve diaphragm type check valve ball check valves single ball ball check valve ball ball check valves and weight safety valve relief valve spring safety valve micro impulse safety valve and safety valve and all safety valve fully enclosed semi-enclosed safety valve relief valve open the relief valve pressure reducing valve piston type pressure reducing valve diaphragm pressure reducing valve gas bag type pressure reducing valve steam trap Mechanical type steam trap free ball float trap lever ball float steam trap free half ball float trap exposure up float type steam trap exposure down float type steam trap hot static type steam trap bellows type steam trap bellows trap double metal plate type steam trap thermodynamic steam trap disc type pulse type steam trap Steam trap labyrinth or hole plate steam trap diaphragm valve globe diaphragm valve roof diaphragm valve disc diaphragm valve multi-purpose valve globe check valve globe check valve globe check valve globe check valve safety valve check ball valve