Steam trap, also known as steam trap, is mainly used to automatically remove non condensable gases such as steam condensate and air from heating equipment or steam pipelines, while preventing steam leakage. The working principle of this device is based on density differences and the characteristics of thermal expansion and contraction. Steam trap valve mainly consists of two parts: valve body and valve core. When steam enters the trap valve, due to the high temperature and high pressure characteristics of steam, the thermal expansion and contraction effect will cause density differences inside and outside the valve core. The upper and lower parts of the valve core are respectively equipped with metal plates, which are tightly attached to the valve seat of the drain valve. When the steam temperature is high, the metal plate on the upper part of the valve core expands due to heat, reduces density, and separates from the valve seat to form a small gap, allowing steam to be discharged through the valve seat. When the steam temperature drops, the metal plate on the upper part of the valve core becomes smaller due to thermal shrinkage, and comes back into close contact with the valve seat, preventing the backflow of condensate water.
The selection of steam trap valves requires consideration of multiple factors, including flow requirements, operating temperature, environmental conditions, volume, operating mode, as well as maintenance and upkeep. When selecting a drain valve, it is necessary to ensure that it can adapt to the requirements of flow, pressure, temperature, etc. in the pipeline, and choose a brand and model that meets the requirements. At the same time, it is necessary to pay attention to the performance and maintenance of the drain valve to ensure the effectiveness and reliability of the equipment.
When installing steam traps, certain rules also need to be . For example, the direction of condensate flow should be consistent with the arrow mark on the installation of the drain valve. The installation position of the drain valve should be as low as possible below the condensate discharge point of the equipment. A filter should be installed in front of the steam drain valve to prevent blockage. A shut-off valve should be installed in front and behind the drain valve for easy disassembly and replacement. If condensate is recovered after the drain valve, the outlet pipe of the drain valve should be connected to the main pipe from above the recovery main pipe.
There are various types of steam trap valves, including:
Mechanical drain valve
Mechanical type, also known as float type, utilizes the density difference between condensate and steam, and through the change in condensate liquid level, the float rises and falls to drive the valve disc to open or close, achieving the purpose of blocking steam and draining water.
It can be divided into:

Float type drain valve

1. Power mechanical pump with built-in drain valve

The advantages and characteristics of built-in drain valves in power mechanical pumps
energy conservation
Recycling condensate to save energy and water resources. The elastic pressure mechanism quickly switches between the condensate water flowing into the pump body and the drainage to prevent delay and leakage of the power medium (steam).
Prevent "retention"
Steam equipment equipped with control valves tends to experience "stagnation", leading to process temperature fluctuations, water hammer, and pipeline corrosion. Installing a power mechanical pump with a built-in drain valve can eliminate this phenomenon.
Easy to operate
Built in steam trap valve, suitable for condensate water recovery with positive and negative pressure fluctuations in equipment. The device is driven by steam and does not require electricity. It can be installed in areas that require explosion-proof measures. No need to remove from the condensate recovery pipeline for maintenance.
2. Thermodynamic steam trap valve
This type of drain valve, based on the principle of phase change, relies on the different thermodynamic principles of flow rate and volume changes when steam and condensate pass through, causing different pressure differentials between the valve disc and the valve disc, driving the valve disc to open and close. Due to the fact that the working power of thermal power type steam traps comes from steam, steam waste is relatively high. Simple structure, water-resistant, with a maximum back of 50%, noisy, frequent valve operation, and short service life.
3. Thermostatic type drain valve

This type of drain valve utilizes the temperature difference between steam and condensate to cause deformation or expansion of the temperature sensing element, which drives the valve core to open and close. The subcooling degree of the thermal static type drain valve is relatively high, generally ranging from 15 degrees to 40 degrees. It can utilize a portion of the sensible heat in the condensate water, and there is always high-temperature condensate in front of the valve without steam leakage, resulting in significant energy-saving effects. It is the most ideal drain valve for steam pipelines, heat tracing pipelines, small heating equipment, heating equipment, and small heating equipment with low temperature requirements.