Introducing our range of ZAES pressure gauge siphon tubes designed to protect instruments in steam and high temperature lines.

The pressure measurement in steam, thermal oils y high temperature fluids requires special protection to prevent damage to the instruments. Bourdon tube gauges are sensitive to excessive heat, as their internal mechanism is designed to work within safe thermal ranges. When the instrument is directly exposed to fluids above its limit, it suffers deformation, loss of accuracy and even irreversible mechanical failure.

To solve this industrial challenge, ZAES introduces its new range of siphon tubes, also known as siphons for pressure gauges, pigtail siphons o cooling tubes, These are essential to thermally insulate the instrument and ensure stable measurement over long periods of operation.

What is a pressure gauge siphon tube and why is it indispensable in steam?

Siphon tubes are fittings designed to create a condensate chamber between the process and the pressure gauge. This chamber is filled with a small volume of condensed fluid (usually water in the case of steam), which acts as a natural thermal insulator.

What happens if a siphon is not installed?

Without a siphon:

• The saturated or superheated vapour comes into direct contact with the pressure gauge.
• The Bourdon tube heats up above its permissible range.
• The internal mechanism is deformed affecting the calibration.
• Mechanical wear is accelerated.
• The instrument may break due to thermal shock.
• The reading becomes unstable or erroneous.

For this reason, international standards and gauge manufacturers recommend the mandatory use of siphons in all steam installations..

The ZAES range of siphon tubes: industrial solutions for steam and high temperatures

ZAES has developed a range of siphons designed to offer stable, durable thermal protection compatible with modern installations. This product family comprises:

1. U-type siphons“

Ideal for:

• vertical lines,
• boilers,
• saturated steam networks,
• installations where the instrument is fixed to a wall or panel.

Its shape generates a large condensate chamber, improving thermal insulation.

2. Pigtail traps (spiral)

These siphons have a spiral geometry that:

• absorbs vibrations,
• prolongs the path of the hot fluid,
• offers superior heat dissipation.

They are commonly used in:

• industrial furnaces,
• superheated steam,
• turbines,
• high pressure steam collectors.

3. Straight models for special installations

Some applications require linear siphons to avoid obstacles or to integrate into confined spaces. ZAES offers this type for compact installations or distributed instrumentation.

Top quality industrial materials

ZAES siphons are made of two key materials:

• Galvanised or carbon steel

Suitable for standard steam, low-medium pressure boilers and applications where corrosive fluids are not present.

• Stainless steel AISI 304 / 316

Recommended for:

• superheated steam,
• thermal oils,
• chemical processes,
• food plants,
• corrosive atmospheres,
• marine environments.

These variants guarantee mechanical strength, durability and operational safety even under extreme conditions.

Full compatibility: BSP and NPT connections

In industrial practice, not all installations share the same thread standard. ZAES has therefore launched its siphons in two versions:

• BSP thread (G) - European standard.
• NPT thread - standard used in America and in imported equipment.

This versatility avoids adapters, leakage and compatibility errors, facilitating direct integration into new or existing instrumentation.

Operational advantages of ZAES siphon tubes

ZAES siphons are designed to offer both technical and operational benefits:

1. Full thermal protection

The condensate inside the siphon acts as a barrier between the steam and the pressure gauge, preventing the instrument from reaching critical temperatures.

2. More stable readings

By avoiding thermal expansion of the Bourdon tube, the gauge needle remains stable and accurate.

3. Longer service life of the pressure gauge

A thermally protected pressure gauge can last from 3 to 5 times more than one exposed directly to steam.

4. Reduced need for recalibration

The protected instrumentation suffers less thermal stress, maintaining its calibration curve longer.

5. Quick and universal installation

No special tools or welding are required: it is simply inserted between the line and the instrument.

Where are ZAES siphons used?

Siphons are an essential part of any plant working with steam:

• Industrial boilers

From small heating boilers to firetube or watertube boilers.

• Steam distribution networks

In textile, food, chemical, pharmaceutical, etc. factories.

• Superheated steam systems

Where extreme heat can destroy instrumentation in minutes.

• Steam turbines

Where pressure stability is critical.

• Chemical and petrochemical plants

Hot fluids, aggressive atmospheres and constant thermal variations.

• Food industry

CIP/SIP processes, steam sterilisation, pasteurisation.

In each of these applications, the siphon is essential to avoid catastrophic gauge failures.

ZAES and the importance of a complete instrumentation ecosystem

Siphon tubes are part of a larger instrument protection strategy.
ZAES recommends combining:

• Siphon (thermal protection)
• Pressure cushioning (mechanical protection)
• Valve for pressure gauge (safe maintenance)

This combination creates a robust and stable system that protects the pressure gauge in all dimensions:

• temperature,
• pressure,
• vibration,
• maintenance.

ZAES versus international manufacturers

The new range positions ZAES as an efficient alternative to brands such as:

• WIKA
• Badotherm
• Winters
• Ashcroft

Offering:

• competitive prices,
• immediate availability,
• European design,
• BSP/NPT compatibility,
• specialised technical assistance,
• high-strength materials.

In a nutshell: ZAES siphons, indispensable protection for steam lines.

The ZAES siphon tubes represent an indispensable solution for any installation handling steam or hot fluids. Their robust design, thermal insulation capability and compatibility with industrial standards make them a key part of modern instrumentation.

With this new range, ZAES reinforces its leadership in the sector and offers industries a reliable tool to ensure accurate and durable pressure measurements.