Stainless Steel Syphon

Stainless Steel Syphon Product Overview

The SIYelectric Stainless Steel Syphon is an instrument protection accessory installed between a process pipeline and a pressure measuring instrument. It is mainly used to protect pressure gauges, pressure transmitters, pressure switches, gauge valves, and needle valves from direct exposure to high-temperature media.

In steam or hot liquid applications, the syphon creates a cooling section before the medium reaches the instrument. For steam pressure measurement, condensate can form inside the syphon and act as a protective barrier, preventing live steam from directly entering the pressure gauge or transmitter connection.

This product is widely used in boiler systems, steam pipelines, hot water systems, thermal oil systems, HVAC heating lines, power plants, chemical plants, food and beverage utilities, and general industrial pressure measurement points.

Product Description

A stainless steel syphon is normally made from a bent stainless steel tube with threaded connections at both ends. According to the shape and installation requirement, it may also be called a pressure gauge syphon, pigtail syphon, coil syphon, U type syphon, steam syphon, or pressure gauge cooling coil.

Its main purpose is to create distance and internal volume between the hot process medium and the pressure instrument. This helps reduce the process temperature transferred to the instrument and protects the sensing element, bourdon tube, diaphragm, sealing parts, or transmitter module.

For pressure transmitters, a syphon is often used when the process temperature is higher than the transmitter can directly withstand, but the application does not require a diaphragm seal or remote capillary seal. It is a simple and economical solution for many standard steam and hot liquid pressure measurement points.

A typical installation arrangement is:

Process Connection → Stainless Steel Syphon → Gauge Valve / Needle Valve → Pressure Gauge or Pressure Transmitter

For safer maintenance, a valve is often installed between the syphon and the instrument so the operator can isolate, vent, calibrate, or replace the pressure instrument more conveniently.

Common Names

This product may be referred to by different names in different markets:

For the website product title, Stainless Steel Syphon is suitable. In the content, these alternative names can be included naturally for SEO coverage.

Main Functions

Temperature Reduction

The syphon helps reduce the temperature transferred from the process line to the pressure instrument. This is especially important in steam, hot water, thermal oil, and high-temperature liquid systems.

For pressure transmitters, excessive temperature may damage the sensor, diaphragm, O-rings, electronic components, or filling oil. A stainless steel syphon helps create a cooling buffer before the medium reaches the transmitter.

Condensate Barrier for Steam Service

In steam applications, condensate can remain inside the syphon. This condensate layer prevents live steam from directly contacting the pressure gauge or pressure transmitter, helping protect the instrument from high temperature.

Minor Pulsation Damping

The bent or coiled tube structure can help absorb part of the pressure impact before it reaches the instrument. It is useful for reducing minor pulsation, vibration, and pressure shock.

For severe pulsation from pumps, compressors, or water hammer, a dedicated pressure snubber or pulsation dampener may still be required.

Instrument Protection

The syphon protects pressure instruments from direct process impact, high temperature, and sudden pressure changes. It can help improve measurement stability and extend the service life of the instrument.

Convenient Instrument Installation

Different syphon shapes and connection types allow flexible installation in pipelines, boiler systems, panels, and local pressure measurement points.

Common Types

Pigtail Syphon

The pigtail syphon has a circular coil shape. It is one of the most common types used for steam pressure measurement. The coil provides cooling length and space for condensate formation.

U Type Syphon

The U type syphon has a simple U-shaped tube structure. It is suitable for installations where the pressure instrument needs a compact cooling section but the coil type is not convenient.

Coil Syphon

The coil syphon provides a longer cooling path in a compact form. It is suitable for pressure gauges and pressure transmitters installed on steam or hot fluid lines.

Customized Syphon

Custom designs can be supplied according to site requirements, including tube size, coil diameter, thread type, length, material, pressure rating, and installation direction.

Technical Specifications

Applications

Pressure Transmitters

The stainless steel syphon is commonly used with pressure transmitters in steam, hot water, and thermal oil pressure measurement. It helps reduce the process temperature reaching the transmitter and protects the sensing element from direct high-temperature exposure.

Typical use:

Steam Line → Syphon → Needle Valve → Pressure Transmitter

This arrangement is often used when a standard threaded pressure transmitter is selected for a hot process line.

Pressure Gauges

The syphon is widely used before pressure gauges in steam lines, boiler systems, and high-temperature pipelines. It protects the gauge bourdon tube from direct steam temperature and helps improve gauge service life.

Pressure Switches

Used before pressure switches in hot process lines or pressure control systems to reduce thermal shock and protect the switching element.

Boiler and Steam Systems

Applied in boiler pressure monitoring, steam headers, steam distribution lines, condensate systems, and heat exchanger pressure measurement points.

Thermal Oil and Hot Water Systems

Suitable for hot oil pipelines, heating systems, hot water circulation systems, and high-temperature liquid process lines.

Industrial Process Systems

Used in chemical plants, power plants, food and beverage utilities, pharmaceutical utilities, HVAC heating systems, and general industrial pressure measurement applications.

Advantages

• Protects pressure transmitters, gauges, and switches from high process temperature.
• Creates a cooling buffer between the process medium and pressure instrument.
• Useful for steam pressure measurement by allowing condensate to form inside the syphon.
• Helps reduce minor pressure pulsation and pressure shock.
• Stainless steel construction provides corrosion resistance and mechanical strength.
• Available as pigtail syphon, coil syphon, U type syphon, or customized type.
• Can be used with gauge valves, needle valves, and instrument manifolds.
• Suitable for boilers, steam lines, hot water systems, and thermal oil pipelines.
• Simple and economical protection accessory for standard pressure measurement points.

Selection Notes

When selecting a stainless steel syphon, confirm the following details:

1. Instrument type
   Confirm whether the syphon will be used with a pressure gauge, pressure transmitter, or pressure switch.
2. Process temperature
   Confirm the process temperature and the maximum allowable temperature of the instrument. For very high temperatures, a diaphragm seal with capillary or other cooling structure may be required.
3. Process pressure
   The syphon pressure rating must match or exceed the maximum working pressure of the process line.
4. Medium type
   Syphons are commonly used for steam and hot liquids. For corrosive chemicals, material compatibility must be checked carefully.
5. Connection size and thread
   Common options include 1/2″ NPT, 1/4″ NPT, G1/2, M20×1.5, or customized threads.
6. Installation space
   Choose pigtail type, U type, or coil type according to the available space and instrument mounting direction.
7. Accessory combination
   A gauge valve or needle valve is often installed between the syphon and the pressure instrument for isolation, calibration, and maintenance.
8. Pulsation condition
   A syphon can reduce minor pulsation, but if the pipeline has strong pump pulsation, compressor pulsation, or water hammer, a dedicated snubber or pulsation dampener should be considered.