Thermodynamic Steam Trap

The Batu Valve thermodynamic steam trap discharges the condensate in a steam line and retains the steam, preventing energy loss. Its construction is simple: the disc is its only moving part.

The steam trap is the first product Batu Valve manufactured, in 1978.

Batu Valve steam trap

Types: BST-100 (without strainer) · BST-Y (with strainer)

Size: DN 15 – 25 · R ½″ – R 1″

Pressure: PN 0.25 – 40

Body: Stainless steel (1.4301)

Moving part: Disc only

Maintenance: Every 6 months

Types

Type	Characteristics
Thermodynamic BST-100	Without strainer
Thermodynamic BST-Y	With strainer; DN 15 – 25, PN 0.25 – 40
Float type BST-S	DN 15 – 50, PN 16

Selection

The steam trap is selected from the capacity diagram. The following information is required for selection:

Inlet pressure of the steam system
Lift height after the trap and the back pressure it creates (1 bar for every 7 – 10 metres of height)
Pressure in the condensate line
Condensate capacity of the heat consumer (multiplied by a safety factor according to the type of application)

Installation and use

The direction arrow must point in the direction of steam flow.
A strainer is installed upstream of the trap.
It is installed on a horizontal line with the disc in the horizontal plane.
Water hardness is to be kept at 5 French degrees.

Operation check

Method	Observation
By sound	A few distinct clicks per minute are normal. A continuous flow sound indicates that the trap is passing steam; no sound at all indicates that it is blocked.
By temperature	Checked by temperature measurement.
Visually	Flash steam at the outlet must not be mistaken for leakage.

The operation of the steam trap is also checked with a flow indicator.

Common faults and causes

Fault	Cause
Continuous steam loss	Particle or score on the seating surface; the most common cause is the absence of a strainer at the inlet
No discharge	Trap blocked or differential pressure insufficient
Very frequent cycling	Trap oversized
Water hammer noise	Condensate accumulating in the collecting line; gradient and sizing are reviewed

Maintenance

The most important element to maintain is the surface on which the disc seats. A trap that has lost its performance passes steam.

The cap is opened anticlockwise with an open-end or ring spanner.
The cap and its threads are inspected.
The disc is removed. If its surface shows blackening, impact marks or scoring, it is cleaned on wet abrasive paper laid on flat glass.
The cleaning motion follows a figure of eight. If the surface is badly damaged the disc is replaced.
The body surface and the lower seating surface of the cap are cleaned in the same way.
The disc is centred on the body and the cap tightened.
On the type with strainer, the plug is removed and the screen is taken out and cleaned.

This maintenance is carried out every 6 months even if the trap is operating without fault.

Tools required: open-end or ring spanner, glass with a flat surface (250 × 350 × 4 mm), grade 0 wet abrasive paper and, where available, lapping compound.

Frequently asked questions

What is the function of a steam trap?Are a steam trap and a condensate trap the same?How is a failed steam trap identified?How often does a steam trap require maintenance?

It discharges the water that condenses in a steam line (condensate) and retains the steam in the line, thereby preventing energy loss.

Yes. Condensate trap is another widely used name for the steam trap.

By its sound: a few distinct clicks per minute are normal. A continuous flow sound indicates that it is passing steam; no sound indicates that it is blocked.

Maintenance is carried out every 6 months even when it is operating without fault: the disc and seating surface are cleaned and, on the type with strainer, the screen is cleaned.