In industrial process lines, it is often important to visually confirm whether fluid is flowing through the pipeline. Operators may need to observe flow direction, continuity, color, clarity or movement directly from the line. For this purpose, a reliable flow monitoring device provides practical support for process safety, maintenance and system control.
The EFD Flow Sight Glass Series is designed to monitor flow inside process pipelines. With its stainless steel body, double-sided glass structure and different connection options, EFD provides a simple and durable solution for visual flow observation in industrial applications.
What Is the EFD Series?
The EFD series is a flow monitoring indicator used to observe the flow inside a pipe. It allows operators to visually check the movement of the fluid in the process line.
The product family includes EFD 10, EFD 20 and EFD 30 models.
EFD 10 is the threaded type.
EFD 20 is the flanged type.
EFD 30 is the mini type.
This model variety allows users to select the correct flow sight glass according to connection type, line size, pressure requirement and application area.
Why Visual Flow Monitoring Matters
In many systems, electrical signals alone may not be enough. Operators may also need direct visual confirmation of flow.
A flow sight glass helps users check whether the medium is moving, whether there is interruption in the line, whether air bubbles are present, or whether the fluid condition has changed.
This makes EFD useful in process lines where simple, direct and continuous visual monitoring is required.
Application Areas
The EFD series can be used in a wide range of fluid applications. The catalog lists application areas such as cold water, hot water, steam, compressed air, fuel oil, pharmaceutical industry and food industry.
It can also be used for general fluid monitoring applications in process lines.
Because the selection depends on the fluid characteristics, users should evaluate the chemical structure, temperature, pressure and process conditions before choosing the correct model and material configuration.
Material Structure
The standard body material of EFD is 304 stainless steel. As an option, 316 stainless steel can be selected.
The sight glass material is heat-treated glass, and the device has a double-sided glass structure. This allows flow to be observed from both sides.
The standard gasket material is Klingrid. Optional gasket materials include PTFE or spiral wound metal gasket.
These material options allow EFD to be adapted to different industrial fluids and process conditions.
Pressure and Temperature Ratings
The standard maximum working temperature of the EFD series is 200 °C.
As an option, the maximum working temperature can be increased to 300 °C.
The standard maximum working pressure is 16 bar. Optional pressure versions are available up to 40 bar.
This makes the EFD series suitable for many process lines where visual monitoring is required under moderate or demanding operating conditions.
EFD 10 Threaded Type
EFD 10 is the threaded type flow sight glass.
It is available with threaded process connections from R 1/2" to R 2". The catalog provides dimensional values according to connection size.
For R 1/2", the total length is 120 mm, body diameter is 60 mm, glass diameter is 50 mm, height is 82.5 mm, K dimension is 30 mm, and wrench size is 27 mm.
For larger sizes such as R 2", the total length is 220 mm, body diameter is 115 mm, glass diameter is 100 mm, height is 155 mm, K dimension is 52.5 mm, and wrench size is 70 mm.
EFD 10 is suitable for applications where threaded installation is preferred.
EFD 20 Flanged Type
EFD 20 is the flanged type flow sight glass.
It is available with flange connections from DN15 to DN50. The dimensions are similar to EFD 10 according to line size, but the connection structure is flanged.
For DN15, the total length is 120 mm, body diameter is 60 mm, glass diameter is 50 mm, height is 82.5 mm, and K dimension is 30 mm.
For DN50, the total length is 220 mm, body diameter is 115 mm, glass diameter is 100 mm, height is 155 mm, and K dimension is 52.5 mm.
EFD 20 is suitable for process lines where flanged mounting is required for stronger mechanical connection or plant standard compatibility.
EFD 30 Mini Type
EFD 30 is the mini type flow display model.
The body material is 304 stainless steel. Available connection sizes are R 1/4" female, R 3/8" female and R 1/2" female.
The total length is maximum 85 mm. The sight tube is borosilicate glass. The paddle material is polypropylene, with a 5-blade structure.
The maximum working pressure is 4 bar, and the maximum working temperature is 80 °C. The O-ring material is NBR.
EFD 30 is suitable for smaller flow lines where compact visual indication is required.
EFD 30 Flow Capacity
The catalog lists flow capacity values for EFD 30 according to connection size.
For R 1/4", the flow rate is 14 L/hour.
For R 3/8", the flow rate is 18 L/hour.
For R 1/2", the flow rate is 28 L/hour.
All three versions have 85 mm total length, 22 mm indicator length, 24 mm wrench size and approximately 0.3 kg weight.
This makes EFD 30 a compact option for low-flow visual monitoring.
Optional Flow Switch Integration
The catalog states that a flow switch can optionally be mounted on the body.
This allows the visual monitoring function to be combined with electrical flow detection when required. In this way, users can both observe flow visually and receive a contact signal for control or alarm purposes.
This option is useful when the process requires operator visibility and automation feedback at the same time.
Installation Recommendation
For healthy operation, the catalog recommends installing a strainer in the line.
This is important because dirt, particles or foreign materials in the fluid may affect the sight glass, sealing surfaces or optional flow switch operation.
Correct installation and fluid compatibility evaluation are important for long service life and reliable observation.
Model Selection
When selecting an EFD model, users should consider the fluid type, operating pressure, operating temperature, connection type and required line size.
EFD 10 is suitable for threaded process lines.
EFD 20 is suitable for flanged process lines.
EFD 30 is suitable for compact and low-flow applications.
Material selection should also be evaluated. Standard 304 stainless steel is suitable for many general applications, while 316 stainless steel may be preferred for more demanding or corrosive fluids.
Ordering Flexibility
The EFD ordering structure allows users to define the model, certificate, process connection, sensor connection, body material, maximum working pressure, maximum working temperature, sight glass type and optional features.
Process connection options include threaded sizes from R 1/4" to R 2" and flanged sizes from DN15 PN16 to DN50 PN16.
Body material options include 304 stainless steel as standard and 316 stainless steel as an option.
Maximum working pressure options include 16 bar, 25 bar and 40 bar. Maximum working temperature options include 200 °C and 300 °C.
Sight glass options include tempered glass versions for PN16, PN25 and PN40.
Why Choose the EFD Series?
The EFD series is a strong choice when an application requires direct visual flow observation in process pipelines.
Its stainless steel body, double-sided glass structure, threaded and flanged model options, high-temperature capability and optional high-pressure versions make it suitable for many industrial sectors.
For operators who need a simple and reliable visual confirmation of flow, EFD provides a practical and durable solution.
Conclusion
The EFD Flow Sight Glass Series is designed for visual monitoring of flow inside industrial process pipelines. With EFD 10 threaded type, EFD 20 flanged type and EFD 30 mini type options, the series covers different installation and application needs.
With standard 304 stainless steel body, optional 316 stainless steel, heat-treated double-sided glass, standard 16 bar / 200 °C rating and optional configurations up to 40 bar / 300 °C, EFD offers a reliable solution for cold and hot water, steam, compressed air, fuel oil, pharmaceutical, food and general fluid applications.