How to choose a drain valve

1、 Determine the pressure difference between the inlet and outlet of the steam trap valve based on actual operating conditions. The inlet pressure of a steam trap refers to the minimum working pressure at the valve inlet; The outlet pressure of the drain valve is the highest possible working back pressure behind the valve. The nominal pressure, nominal diameter, maximum allowable pressure, maximum allowable temperature, maximum working pressure, minimum working pressure, maximum back pressure rate, condensate flow rate, etc. of the drain valve should comply with the operating conditions of the steam pipeline network. When selecting a steam trap, consideration should also be given to the fact that the rated discharge capacity of the trap is equal to the condensate production of the steam using equipment multiplied by the selected ratio. The ratio selection is shown in the table below

2、 Determine the amount of condensation that may occur during normal operation based on process conditions, multiply it by a correction factor, and select a certain type of drain valve based on its drainage capacity.

3、 There are many types of drain valves with different structural principles, so different structural forms should be selected according to different usage scenarios (see Table 2)

In situations where condensate needs to be immediately drained:

For steam turbines, steam pumps, steam main pipelines, etc., it is not advisable to use steam traps with subcooling, such as pulse type steam traps and constant temperature corrugated pipe type steam traps

When the condensate water is below 15% of the rated maximum discharge capacity:

Pulse type drain valves should not be used because under these conditions, fresh steam is prone to flow out of the drain hole.

The attachments around offices, schools, research and residential areas require a quiet environment:

It is not advisable to use noisy thermal power drain valves. Constant temperature drain valves and floating ball drain valves should be selected because they operate slowly and have low impact force

• Drain valve for outdoor work:

Mechanical drain valves are generally not suitable for use. When necessary, antifreeze protection should be provided.

The steam device is not allowed to accumulate condensed water:

A drain valve that can continuously remove condensed water, such as a floating ball drain valve, should be selected.

In situations where both the removal of condensed water and the timely removal of non condensable gases are required:

A drain valve with dual functions of drainage and exhaust should be selected.

In the steam pipeline network, if it is necessary to use working back pressure to recover condensed water:

High back pressure rate drain valves, such as mechanical drain valves, should be selected.