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Basic types of traps and mechanical traps

There are many types of traps, each with different properties. When using a steam trap, first select the special performance to meet the optimal operation of the steam heating equipment, and then consider other objective conditions, so that the choice of the trap you need is correct and effective. This article introduces the basic types of traps and mechanical traps.
Basic types of traps and mechanical traps
The basic function of the steam trap is to discharge the condensate, air and carbon dioxide gas in the steam system as quickly as possible; at the same time, the steam leakage is automatically prevented to the utmost. There are many types of traps, each with different properties. When using a steam trap, first select the special performance to meet the optimal operation of the steam heating equipment, and then consider other objective conditions, so that the choice of the trap you need is correct and effective.
According to the working principle of the steam trap, the Ward WODE steam trap can be converted into the following three types:
Mechanical type: Actions based on changes in the level of condensate in the steam trap, including:
Float type: the float is a closed hollow sphere
Open up float type: float is open barrel type
Open down float type: float is open to the barrel type
Thermostatic type: Acts on changes in liquid temperature, including:
Bimetal: sensitive original is bimetal
Steam pressure type: sensitive original is bellows or ink cartridge, filled with volatile liquid inside
Thermodynamic type: Acting on changes in the thermodynamic properties of the liquid.
Disc type: due to the different flow rates of liquid and gas under the same pressure, the different dynamic and static pressures generated drive the disk valve
Pulse type: When condensed water of different temperatures passes through the two-pole series orifice plate, different pressures are formed between the two-pole orifice plate to drive the valve flap to move.
There are many manufacturers of traps in China, and the connection sizes are mostly not uniform. Mainly divided into the following major categories:
(1) The general category based on JB/T2203-1999 "Train Structure Length". At present, most of the domestic steam trap manufacturers are designed and produced according to this standard. The maximum nominal diameter of the micro-open safety valve is D NI 00, and the maximum nominal diameter of the full-open safety valve is DN200. There are two specifications of DN65 and DN125 in the middle. According to the specifications of the valves produced by the factory and the information obtained, the nominal diameter of the micro-opening safety valve is up to DN250, and the nominal diameter of the full-opening safety valve is DN400.
No steam trap jargon to explain terminology noun interpretation
01 Maximum allowable pressure The highest pressure that the trap housing can withstand at a given temperature
02 Working pressure Pressure at the inlet end of the trap under working conditions
03 Maximum working pressure Under the correct operating conditions, the maximum pressure at the inlet end of the trap is given by the manufacturer.
04 Minimum working pressure Under the correct action, the lowest working pressure at the inlet end of the trap
05 Working back pressure Pressure at the outlet end of the trap under working conditions
06 Maximum working back pressure At the highest working pressure, the highest pressure at the outlet end of the trap can be operated correctly
07 Back pressure rate Percentage of working back pressure and working pressure
08 Maximum back pressure rate Percentage of maximum working back pressure and maximum working pressure
09 Working pressure difference The difference between working pressure and working back pressure
10 Maximum differential pressure Maximum difference between working pressure and working back pressure
11 Minimum differential pressure Minimum difference between working pressure and working back pressure
Steam trap working principle
12 Operating temperature Temperature at the inlet end of the trap under operating conditions
13 Maximum operating temperature The saturation temperature corresponding to the highest working pressure
14 Maximum allowable temperature The maximum temperature that the trap housing can withstand at a given temperature
15 valve opening temperature inlet temperature when the trap is open during the drain temperature test
16 Shutoff valve temperature The inlet temperature at which the trap is closed during the drain temperature test
17 Drainage temperature The temperature at which the trap can continuously discharge hot condensate
18 Maximum Drainage Temperature The maximum temperature at which the trap can continuously discharge hot condensate at the highest working pressure
19 Undercooling The absolute value of the difference between the condensate temperature and the saturation temperature at the corresponding pressure
20 Open valve undercooling The absolute value of the difference between the open valve temperature and the saturation under the corresponding pressure
21 OFF valve undercooling The absolute value of the difference between the closing valve temperature and the saturation temperature at the corresponding pressure
22 Maximum undercooling Maximum value in valve overcooling
23 Minimum subcooling The maximum value of the valve undercooling
24 Condensate Water Discharge The maximum weight of condensate that can be drained within one hour of a given differential pressure and 20 degrees.
25 Hot condensate displacement The maximum weight of condensate that can be drained within one hour of a given differential pressure and temperature.
26 Leakage The amount of fresh steam leaking from the trap per unit time
27 No-load leakage The amount of steam leaking under the condition of fully saturated steam before the trap
28 Loaded steam leakage The steam trap of a steam trap at a given load rate
29 No-load leakage rate The percentage of non-load leakage and the maximum amount of hot condensate discharge at the corresponding pressure
30 Loaded steam leakage rate The percentage of steam leakage in the load and the actual hot condensate discharge during the test period
31 Negative load The percentage of actual hot condensate discharge during the test period and the maximum hot condensate discharge at the test pressure
Mechanical type traps Mechanical type, also known as float type, utilizes the difference in density between condensed water and steam. By changing the level of condensed water, the float lifts the valve flap open or closed to achieve steam-blocking drainage. The mechanical type steam trap has a small degree of subcooling and is not affected by the working pressure and temperature change. Water is discharged, and no water is stored in the heating device, so that the heating device can achieve the best heat exchange efficiency. With a maximum back pressure of 80% and high working quality, it is the most ideal steam trap for production process heating equipment.
Mechanical traps are free float type, free half float type, lever float type, inverted bucket type, etc.
1. Free float trap:
The free float trap has a simple structure, and there is only one stainless steel hollow float with fine moving parts inside. It is both a float and a starter, no fragile parts, and has a long service life. The YQ trap has a Y series automatic inside. The air exhaust device is very sensitive and can automatically discharge air and has high work quality.
When the equipment is started, the air in the pipeline is discharged through the Y series automatic air exhaust device. The low temperature condensed water enters the trap. The liquid level of the condensate rises, the float rises, the valve opens, the condensate is quickly discharged, and the steam enters quickly. The equipment and equipment are rapidly warmed up, and the temperature-sensitive liquid of the Y-series automatic air-discharging device expands, and the automatic air-discharging device is closed. The trap begins to work normally, and the float moves up and down with the condensate level, blocking steam drainage. The valve seat of the free float trap is always below the liquid level, forming a water seal, no steam leakage, and the energy saving effect is good. The minimum working pressure is 0.01Mpa, and it is not affected by temperature and working pressure fluctuations from 0.01Mpa to the maximum operating pressure range, and continuous drainage. It can discharge condensed water with saturated temperature, the minimum degree of subcooling is 0 °C, and there is no water in the heating equipment, which can make the heating equipment achieve the best heat exchange efficiency. With a back pressure of more than 85%, it is one of the most ideal steam traps for production process heating equipment.
2. Free semi-float trap:
The free semi-float trap has only one semi-floating ball barrel as the moving part, and the opening is downward, and the barrel is the opening and closing member and the sealing member. The entire spherical surface can be sealed, has a long service life, can resist water hammer, has no wearing parts, no faults, is durable, and has no steam leakage. The back pressure ratio is more than 80%, and the condensed water can be discharged at a saturated temperature. The minimum degree of subcooling is 0 ° C. There is no water in the heating equipment, which can make the heating equipment achieve the best heat exchange efficiency.
When the device is just started, the air and low-temperature condensate in the pipeline enter the trap through the launch tube. The bimetal evacuation element in the valve bounces the bucket, the valve opens, and the air and low-temperature condensate are quickly discharged. When the steam enters the barrel, the barrel generates upward buoyancy, and the temperature inside the valve rises, the bimetal evacuation element contracts, the ball floats to the valve port, and the valve closes. When the steam in the bucket becomes condensed water, the bucket loses buoyancy and sinks, the valve opens, and the condensate is quickly discharged. When the steam re-enters the barrel, the valve closes again, intermittently and continuously.
3. Rod float trap:
The basic characteristics of the lever float trap are the same as that of the free float type. The internal structure is that the float connecting rod drives the valve core, and the valve is opened and closed with the liquid level of the condensate. Lever-float trap uses double seat to increase condensate displacement
It has a large displacement and a maximum displacement of 100 tons/hour. It is the most ideal steam trap for large heating equipment.
4. Inverted bucket trap:
The inside of the inverted bucket type trap is an inverted bucket for the liquid level sensitive component, the bucket opening is downward, and the inverted bucket connecting the lever drives the valve core opening and closing valve. The inverted bucket type trap can discharge air, is not afraid of water hammer, and has good anti-fouling performance. The degree of undercooling is small, the leakage rate is less than 3%, the maximum back pressure is 75%, the connection is more, and the sensitivity is not as good as that of the free float trap. Because the inverted bucket type steam trap is closed by steam buoyancy, the working pressure difference is less than 0.1MPA, which is not suitable for use.
When the device is just started, the air in the pipeline and the low-temperature condensed water enter the trap, and the inverted bucket falls by its own weight. The inverted bucket connects the lever to drive the valve to open the valve, and the air and low-temperature condensate are quickly discharged. When the steam enters the inverted bucket, the steam of the inverted bucket generates upward buoyancy, and the inverted bucket rises to connect the lever to drive the valve core to close the valve. There is a small hole in the inverted bucket. When a part of the steam is discharged from the small hole, the other part of the steam generates condensed water. The inverted bucket loses buoyancy and sinks by its own weight. The inverted bucket connects the lever to drive the valve to open the valve. Work, intermittent drainage.
5. Combined superheated steam trap:
The combined superheated steam trap has two isolated valve chambers, which are connected by two stainless steel tubes to the upper and lower valve chambers. It is a combination of a floating ball type and an inverted bucket type steam trap. The valve structure is advanced and reasonable, in overheating, high pressure, Under the condition of small load, it can discharge the condensed water formed when the superheated steam disappears in time, effectively prevent the superheated steam from leaking, and the work quality is high. The maximum allowable temperature is 600 °C, the valve body is all stainless steel, the valve seat is made of hard alloy steel, and the service life is long. It is a special steam trap for superheated steam. It has obtained two national patents and filled the domestic blank.
When the condensed water enters the lower valve chamber, the float of the sub-valve rises with the liquid level, and the float ball closes the inlet of the steam pipe. The condensed water rises to the main valve chamber through the water inlet conduit, and the inverted bucket falls by its own weight, driving the valve core to open the main valve and discharging the condensed water. When the condensate level of the secondary valve chamber drops, the float drops with the liquid level and the secondary valve opens. The steam enters the inverted bucket in the upper main valve chamber from the inlet pipe, and the inverted bucket generates upward buoyancy, and the inverted bucket drives the valve core to close the main valve. When the condensate level of the secondary valve chamber rises again, the next cycle begins again, intermittently draining.

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