SLR Float Steam Trap: Reliable Drainage Without Steam Locking

In applications such as drying cylinders on paper machines or rotating cylinders on corrugators, steam sometimes reaches the steam trap before the condensate, holding a float trap closed and stopping condensate discharge. An SLR float steam trap is a special float trap that solves this “steam locking” problem with an integral needle valve, ensuring uninterrupted condensate removal.

This article explains why steam locking occurs, how the SLR feature works, and covers the technical data and applications.

What Is Steam Locking and Why Does It Matter?

In rotating cylinders, condensate is removed through a siphon pipe inside the cylinder. When steam instead of condensate enters the siphon, it travels to the trap; with no condensate in its body, the float trap stays closed. Because the line between the cylinder and the trap remains filled with steam, condensate cannot flow to the trap and builds up inside the cylinder. This is called steam locking; heat transfer falls, the cylinder surface temperature becomes uneven and product quality suffers.

How Does the SLR Feature Work?

An SLR (Steam Lock Release) trap has a small bypass path in parallel with the main float valve, adjusted by a needle valve. The needle valve continuously passes a small, controlled amount of steam. This clears the steam from the trap inlet, allowing condensate to reach the trap so the float can keep operating normally.

• Float: Opens and closes the main orifice according to the condensate level, discharging condensate continuously in proportion to the load.
• Needle valve (SLR): Provides an adjustable, limited steam bypass to prevent steam locking.
• Thermostatic capsule: Discharges air and non-condensable gases at start-up, preventing air accumulation and the problems it causes.

Advantages

• Uninterrupted condensate discharge: With steam locking released, condensate does not collect in cylinders and similar equipment.
• Built-in air venting: The thermostatic capsule vents air and shortens heat-up time.
• Faster start-up: Because the thermostatic capsule also passes cold condensate below steam temperature, it assists the float valve with discharge during start-up.
• Durable materials: Ductile iron body and all-stainless-steel internals ensure long service life.

Technical Data

Applications

• Rotating drying cylinders
• Corrugated board machines
• Paper mills

Frequently Asked Questions

Conclusion

SLR float steam traps keep condensate flowing in rotating cylinder applications prone to steam locking, protecting heat transfer and product quality. For other models, browse our float steam traps product group, or call ORFA at +90 224 444 67 32 for help selecting the right trap.