What is a Steam Trap?

Have you ever heard of a steam trap? It may sound like a complicated piece of equipment, but it plays a crucial role in the functioning of steam systems.

Basic Operation

A steam trap is a device used in steam systems to remove condensate and prevent steam from escaping. It operates based on the principle of density.

When steam enters the trap, it rises to the top, whereas condensate, which is denser, collects at the bottom. The trap contains a valve that opens to release the condensate and then closes to prevent any steam from escaping. This process is crucial for maintaining the efficiency and safety of steam systems.

It’s important to regularly inspect and maintain steam traps to ensure their proper functioning. A malfunctioning steam trap can lead to reduced system efficiency, increased energy costs, and even safety hazards.

Is There More Than One Type of Steam Trap Available?

There are several different types of steam traps available, each with its own unique benefits and drawbacks.

Mechanical Trap

The most common type of steam trap is the mechanical trap, which uses a valve to open and close based on the level of condensate in the system. This type of steam trap usually operates in one of two ways: either by using a temperature-sensitive element to open and close the valve or by using a weighted element that opens when condensate is present and closes when steam is present.

Thermostatic Trap

The thermostatic trap’s operation is based on the difference in temperature between the steam and the condensate. When the temperature of the condensate exceeds a specific set point, the trap opens, allowing the condensate to be discharged. The trap then closes once the temperature drops below the set point, preventing steam from escaping.

Inverted Bucket Traps

Inverted bucket steam traps work by using the principle of buoyancy to control the flow of steam and condensate in a system.

The way they work is simple yet effective. The trap consists of a bucket that is inverted over a valve. When steam enters the trap, it fills up the bucket and causes it to float, which in turn opens the valve and allows the steam to pass through. As condensate accumulates in the trap, the bucket sinks, closing the valve and preventing the escape of steam.

Float & Thermostatic Trap

The float and thermostatic steam trap works by using a float and a thermostatic element to control the flow of condensate.

The float rises and falls with the level of condensate, opening and closing the valve to control the discharge of condensate. Meanwhile, the thermostatic element responds to changes in temperature, regulating the flow of steam and preventing overheating of the system.

Bimetallic Trap

A bimetallic steam trap works by using two different metals with different coefficients of thermal expansion.

When steam flows through the trap, the bimetallic strip expands and opens the valve, allowing the condensate to be removed. When the steam cools and condenses, the strip contracts and closes the valve, preventing the steam from escaping.

Why are Steam Traps Installed?

Steam traps are installed to remove condensate and other non-condensable gases from the system.

Without steam traps, condensate would accumulate in the pipes, which could cause damage or reduce the efficiency of the system.

By removing the condensate, steam traps help to maintain the integrity and efficiency of the system.

In addition, steam traps also help to conserve energy by ensuring that only steam, not condensate, is used to heat the system.

What's Wrong with Using a Manual Valve?

Using a manual valve instead of a steam trap can lead to inefficiencies and safety concerns. Opening and closing a manual valve requires manual intervention, which can lead to human error and inconsistent control of steam flow.

Manual valves also do not have the ability to automatically adjust to changes in steam pressure or temperature, leading to potential damage to equipment and a decrease in energy efficiency.

Furthermore, manual valves cannot provide the same level of safety features as steam traps. Steam traps automatically discharge condensate, which can prevent water hammer and corrosion. They also have the ability to automatically shut off steam flow in the event of a malfunction or blockage.


In conclusion, a steam trap may seem like a small and insignificant component, but it plays a crucial role in ensuring the efficiency and safety of steam systems. By understanding what a steam trap is and how it works, you can make informed decisions about maintaining and optimising your steam system. So, keep an eye on your steam traps and keep the steam flowing!