(1) Terminology of steam traps

Load rate: The percentage of the actual heat condensate displacement during the test time to the maximum heat condensate displacement under the test pressure.

(2) Capacity and safety rate of steam traps

When selecting steam traps, it is necessary to fully understand the forms, purposes, and characteristics of steam using equipment such as steam delivery pipes and various heat exchangers, and accurately grasp the capacity of the equipment itself, which is a prerequisite. If the capacity of the steam using equipment is known, the capacity of the steam trap used can also be determined. The capacity of the steam trap must be determined according to the following principles:
Capacity of steam usage equipment (condensate production) × Safety rate=capacity of steam trap.
The safety rate is the estimated Factor of safety that can ensure the normal operation of the steam trap when there is an error between the actual condensate production of the steam using equipment and the marked capacity when determining the capacity of the steam trap. This safety rate is not simply stipulated in theory and cannot be calculated; It is not entirely based on empirical data. Generally speaking, the best way to consider safety is to directly inquire with the manufacturer of the drain valve. If the safety rate of the steam trap is not appropriate when selecting it, causing the capacity of the steam trap to be too large or insufficient, it will have extremely negative consequences.
If the safety rate is too high, that is, when installing and using steam traps with excessive capacity, the following drawbacks will occur:
The capacity of steam traps can increase costs.
If the steam trap is operated intermittently, excessive capacity will prolong the operation cycle of the trap, increase the average retention of condensate, and reduce the capacity of the steam equipment.
For steam traps that operate continuously (proportionally) like floating ball traps, due to the small opening of the valve disc, excessive capacity can cause galling on the valve seat (when high-speed fluid passes through narrow gaps, the contact surface corrodes and forms grooves), causing damage to the valve seat and causing leakage.
Shorten the service life of steam traps.
On the contrary, if the safety rate is too low, it will cause the capacity of the drain valve used to be too small, and the following faults will occur:
Unable to adapt to the load changes of steam using equipment, resulting in a significant decrease in operational efficiency.
The condensed water through the drain valve often reaches the maximum limit, making the valve disc and valve seat prone to corrosive damage.
Shorten the service life of steam traps.
Therefore, when selecting steam traps, it is not only necessary to conduct comprehensive research on the type and capacity of the traps, but also to receive guidance from the trap manufacturer.

(3) Selection of steam trap valves

When selecting steam traps, the shortest form of use must be selected according to the type of steam usage device and usage conditions. Therefore, it is necessary to correctly grasp the characteristics and usage conditions of steam usage devices. When determining the type of steam trap, it is necessary to have a detailed understanding of the following items in order to select a steam trap that meets the usage requirements.
The condensate load of the steam usage device and the load characteristics of the condensate.
Steam conditions: pressure, temperature, saturated steam or Superheated steam.
Back pressure condition: Discharge or recovery of condensate into the atmosphere (what is the back pressure).
Valve body material.
Connection form.
Safety rate.
Others: the corrosiveness of condensed water; The possibility of water hammer generation; Will freezing occur; Are there clear requirements for noise and environmental pollution; The difficulty of maintenance and inspection, etc.
In addition, when selecting steam traps, attention should be paid to the selection conditions of steam traps, namely:
Choose a type that meets the usage conditions.
Choose a capacity that is suitable for the usage conditions.
Choose good durability that meets the requirements of usage conditions.
Choose products that are easy to repair.