Valve terms and its performance parameters

Valve terms and its performance parameters:


No.

Terminology

Instructions

1

The main performance parameters

Indicates the main parameters of the valve, such as nominal pressure, nominal passage, working temperature

2

Nominal pressure

Is a pressure-related designation number expressed as a number. It is a convenient circular integer for reference purposes.

3

Nominal diameter

Is a numerically represented size common to all accessories in a piping system to distinguish those parts represented by threads or outer diameters. The nominal diameter is a convenient round number for reference, and it is not strictly related to the processing size.

4

Working pressure

The pressure of the valve at the applicable medium temperature

5

Operating temperature

The temperature of the valve under the applicable medium

6

Suitable medium

Valve applicable media

7

proper temperature

Suitable media and temperature range for valves

8

Shell test

Pressure test of the entire valve housing, which is a combination of a valve body and a bonnet. The purpose is to verify the tightness of the valve body and the valve cover and the pressure resistance of the entire housing including the joint between the valve body and the valve cover.

9

Shell test pressure

The pressure at which the valve conducts the shell test

10

Seal test

Testing of the sealing performance of opening and closing parts and valve body seals

11

Seal test pressure

The pressure specified when the valve conducts the sealing test

12

Upper seal test

Testing of the sealing performance of the valve stem and the bonnet sealing pair

13

Leakage

For the valve seal test, within the specified duration from the sealing surface

14

Goodness of fit

The ratio of the radial minimum contact width of the sealing pair to the minimum sealing surface width in the sealing pair

15

Types of

Classification of valves by application or main structural features

16

model

According to the type, transmission mode, structural characteristics of the connection type, valve seat sealing surface material and nominal pressure, etc.

17

The main dimensions

Valve opening and closing height, handwheel diameter, connection size, etc.

18

Connection size

The size of the pipe connection part of the valve

19

Setting pressure

The predetermined pressure at which the relief valve begins to open under operating conditions. At this pressure, the force to open the valve flap and the force to hold the valve flap in place on the valve seat are balanced

20

Over pressure

Refers to the increase in pressure over the setting pressure of the safety valve, usually expressed as a percentage of the set pressure

twenty one

Return pressure

The valve flap is again in contact with the valve seat, ie when the opening height becomes zero, the static pressure at the inlet

twenty two

Open and close pressure difference

The difference between the setting pressure of the safety valve and the pressure of the return seat, usually expressed as a percentage of the setting pressure

twenty three

Cold test differential pressure

The safety valve is adjusted on the test bench to the static pressure at the inlet when it starts to open. This pressure contains corrections for operating conditions such as back pressure and temperature.

twenty four

Discharge pressure

Set pressure plus pressure

25

Back pressure

It is the pressure formed at the outlet of the valve when the medium flows into the discharge system through the safety valve.

26

Additional back pressure

The static pressure present at the outlet of the safety valve when the device is operating is caused by other pressure sources in the exhaust system.

27

Open height

Actual lift of disc from closed position

28

Starting lift

Refers to the initial lift, which causes the first displacement indication on the displacement transducer or similar instrument

29

Flow area

Refers to the minimum cross-sectional area (but not the "curtain" area) between the valve's inlet end and the seat's sealing surface. It is used to calculate the theoretical displacement without any resistance effect.

30

Flow path diameter

Corresponds to the diameter of the flow area

31

Curtain area

Cylindrical or conical shaped passage area formed between the sealing surfaces when the valve plate rises above the valve seat

32

Theoretical displacement

The calculated discharge capacity of the theoretical nozzle with the cross-sectional area of the flow passage equal to the flow area of the safety valve

33

Displacement coefficient

The ratio of actual displacement to theoretical displacement

34

Rated displacement coefficient

The product of displacement coefficient and reduction factor (take 0.9)

35

Rated displacement

The part of the actual displacement that is allowed to be used as a reference for the safety valve, ie, the value calculated by the following a, b, or c

a, actual displacement × reduction coefficient (take 0.9)

b, theoretical displacement × displacement coefficient × reduction coefficient (take 0.9)

c, theoretical displacement × rated displacement coefficient

36

Equivalent calculation

When the pressure, temperature or characteristics of the fluid is different from the rated displacement of the mine, the calculated displacement of the safety valve

37

Frequency jump

The safety valve clapper rapidly moves back and forth, and the valve seat contacts the valve seat during movement.

38

Flutter

Safety valve clapper rapidly moves back and forth, the valve does not touch the seat in motion

39

Static features

The relationship between the outlet pressure of the pressure reducing valve, the inlet pressure, and the flow rate under steady flow conditions

40

Dynamic characteristics

Under the influence of sudden change of inlet pressure, flow rate, or other disturbance factors, the pressure of outlet valve is related to the flow rate.

41

Traffic characteristics

In the steady flow state, when the inlet pressure and other parameters are constant, the pressure of the relief valve as a function of the flow rate

42

Pressure characteristics

Under steady flow conditions, when the flow rate and other parameters are constant, the pressure of the relief valve as a function of the inlet pressure

43

Static characteristic deviation

The change of outlet pressure caused by the change of parameters such as inlet pressure and flow rate of pressure reducing valve under steady flow state

44

Flow characteristic deviation

In the steady flow state, when the inlet pressure and other parameters are unchanged, the outlet pressure change value caused by the change of the pressure reducing valve flow rate

45

Pressure characteristic deviation

In the steady flow state, when the flow rate and other parameters are constant, the outlet pressure change caused by the change of the inlet pressure of the pressure reducing valve

46

Relative static deviation

Pressure regulator valve static characteristic deviation and given outlet pressure ratio

47

Relative flow characteristic deviation

Pressure valve flow rate deviation ratio given outlet pressure

48

Relative pressure characteristic deviation

Pressure valve pressure characteristic deviation and given outlet pressure ratio

49

Pressure increase factor

Relief valve pressure drops from nominal to zero (less than the allowable leakage)

50

Maximum flow

The upper limit of the flow that can be reached when the deviation is within the specified range at a given outlet pressure

51

Decompression ratio

The ratio of the absolute pressure of the inlet and outlet of the pressure reducing valve

52

Closing pressure

The media stops flowing and the outlet pressure when the pressure relief valve is fully closed

53

Maximum allowable pressure

The maximum pressure that the steam trap housing can withstand for a given temperature

54

Working pressure

Pressure at the inlet of the trap at operating conditions

55

Maximum working pressure

Under the correct operating conditions, the maximum pressure at the inlet end of the trap. It is given by the manufacturer

56

Minimum working pressure

Under the correct action conditions, the minimum working pressure at the inlet end of the trap

57

Work back pressure

Under operating conditions, the pressure at the outlet end of the trap

58

Maximum working back pressure

The maximum pressure at the outlet end of the trap at the maximum operating pressure

59

Back pressure rate

Percentage of working back pressure and working pressure

60

Highest back pressure rate

Percentage of maximum working back pressure and maximum working pressure

61

Working pressure difference

Difference between working pressure and working back pressure

62

Maximum pressure difference

Maximum difference between working pressure and working back pressure

63

Minimum pressure difference

Minimum difference between working pressure and working back pressure

64

Operating temperature

Trap inlet temperature at operating conditions

65

Maximum operating temperature

Saturation temperature corresponding to the highest working pressure

66

Maximum allowable temperature

Maximum temperature at which the trap can last for a given pressure

67

Open valve temperature

Drain temperature test, inlet temperature when the trap opens

68

Close valve temperature

Drain temperature test, inlet temperature when the trap closes

69

Drainage temperature

Traps continuously discharge hot condensation water

70

Maximum drainage temperature

Maximum temperature at which the steam trap can continuously discharge hot condensate under the highest working pressure

71

Undercooling

The absolute value of the difference between the condensate temperature and the saturation temperature at the corresponding pressure

72

Open valve overcooling

The absolute value of the difference between the valve opening temperature and the saturation temperature at the corresponding pressure

73

Maximum coldness

Maximum value of valve open subcooling

74

Minimum degree of undercooling

Closed valve overcooling

75

Condensate water discharge

Maximum importance of condensate discharge within 1 h of a trap at a given pressure differential and 20°C

76

Thermal condensation displacement

The maximum importance of condensing water in the trap 1h at a given pressure difference and temperature

77

Steam leakage

The amount of fresh steam leaking from the trap per unit of time

78

No load leakage

Steam leakage in fully saturated steam before the trap

79

Loaded steam leakage

Steam trap steam leakage at a given load rate

80

No load leakage rate

No-load steam leakage and the corresponding pressure maximum percentage of hot condensate water discharge

81

Load leakage rate

The percentage of load steam leakage and the actual thermal condensate discharge during the test time

82

Load factor

The actual thermal condensate discharge at the test time as a percentage of the maximum thermal condensate discharge at the test pressure