Threaded Sight Flow Indicators
Last Updated: April 1, 2025
Description
Threaded Sight Flow Indicators are devices used to provide a visual indication of the flow of liquids through a pipeline. They are equipped with visual indicators such as flappers or propellers that move in response to the flow of the medium, allowing operators to observe the flow direction and rate. These indicators are typically designed for use with clear, translucent, or dark fluids.
Working Principle
Threaded Sight Flow Indicators operate by incorporating visual elements like flappers or propellers that react to the flow of the medium. When the fluid flows through the indicator, these elements move, providing a visual confirmation of flow direction and rate. The movement of these components is directly related to the flow, making it easy for operators to monitor the process. This type of indicator is particularly useful because it does not require a power supply and offers a simple, reliable method for on-site flow monitoring.
Applications
Threaded Sight Flow Indicators are used in various applications where visual confirmation of fluid flow is necessary. For example, they are often installed in soil remediation systems to visually confirm the presence of flow, with streamers fluttering within the chamber when flow is present. They are also used downstream of injection systems to verify the presence of process additives in pipelines.
Advantages over other Sight Flow Indicators
One of the main advantages of Threaded Sight Flow Indicators is their ability to handle high pressures and provide dependable on-site flow monitoring without the need for a power supply. They are also low-cost solutions that offer low pressure loss, making them suitable for a wide range of applications. Additionally, they are capable of measuring liquids, gases, or steam, providing versatility in different industrial settings.
Limitations
Threaded Sight Flow Indicators have certain limitations, such as susceptibility to sticking over time due to fouling contaminants. The presence of nooks and crannies in the flow stream can lead to clogging and contamination of subsequent samples. They are not suitable for media that could coat the measuring tube or interfere with the sight glass, and their measuring accuracy can be affected by process conditions and fluid properties.
Considerations
When considering the use of Threaded Sight Flow Indicators, it is important to evaluate factors such as initial costs, operating expenses, and durability. These indicators are generally low-cost and do not require a power supply, which can reduce operating expenses. However, their durability may be compromised by fouling contaminants, leading to potential maintenance and replacement costs. Accuracy can be influenced by the specific properties of the fluid being measured, and regular calibration may be necessary to ensure reliable performance.
from Kaydon Filtration Corporation
The Model 4B Gravity Sight Feed Oiler offers a clear oil flow view with fine tune-control. The Model 4B allows oil flow by gravity to a lubrication point. The double-window design permits observation of the oil stream from either side. This oiler provides trouble-free service with little or no... [See More]
- Connection Type: Threaded
- Thread Size: 0.5000
- Flow Indicator Style:: Drip Tube
- Pressure Range: 125
from Plast-O-Matic Valves, Inc.
Series GX Single-wall sight glass for liquids compatible with acrylic. 1/2 ″ – 3 ″ sizes, NPT or socket connections in PVC or polypro. Fluttering streamers optional. Series GY Double-wall sight glass for liquids compatible with Pyrex inner wall. 1/2 ″ – 3 ″ sizes,... [See More]
- Connection Type: Threaded
- Thread Size: 0.5000
- Flow Indicator Style:: Full View
- Length (Face to Face): 4.75
from Kaydon Filtration Corporation
Kaydon Model 825 Overflow Sights are designed for convenient observation of liquid flow and are extremely practical for maintaining a desired or fixed level of liquid circulating in a system. The metal top has a 1/2" NPT vent connection to connect into the reservoir above the maximum liquid level... [See More]
- Connection Type: Threaded
- Thread Size: 2 to 3
- Flow Indicator Style:: Plain; Full View
- Body Materials: Other; Cast Iron Body
from Kaydon Filtration Corporation
The Model 902A Pressure Feed Oiler is a combination of a metering valve and flow indicator. It is used for the distribution and supply of oil under pressure to lube points of use, such as bearings and gears. It is particularly useful where several lubrication points are served from the same piping... [See More]
- Connection Type: Threaded
- Thread Size: 0.7500
- Flow Indicator Style:: Plain; Full View
- Pressure Range: 125
from OPW Engineered Systems
OPW has been manufacturing sight flow indicators for over 60 years. Our experience has led to many innovations in design and manufacturing, making VISI-FLO ® the most thoroughly-engineered Sight Flow Indicator on the market. VISI-FLO ’s are available in two series: the Standard 1400... [See More]
- Connection Type: Threaded
- Thread Size: 0.2500 to 4
- Flow Indicator Style:: Flapper (optional feature); Rotor (optional feature); Drip Tube (optional feature)
- Pressure Range: 135 to 200
from Oil-Rite Corp.
Full Vision Flow Sights are used in oil lines to allow visual observation of the flow and clarity of oil. The large size of the flow sight permits maximum visibility of the oil, even from a distance. They are often used at elevated heights to tell at a glance whether oil is circulating. Liquid flows... [See More]
- Connection Type: Threaded
- Thread Size: 1
- Flow Indicator Style:: Full View
- Pressure Range: 125
from DME Company
Visual Flow indicators provide simple, effective. confirmation of coolant flow in mold systems. Prevent. dangerous and costly blocked pipe situations. Bright, visual orange spinning rotor. Operating temperature 212 ºF (100 ºC) max. Pressure 100psi max. 1 ⁄4" or 1 ⁄2" ports. [See More]
- Connection Type: Threaded
- Thread Size: 0.2500 to 0.5000
- Flow Indicator Style:: Rotor
- Pressure Range: 100
from Gems Sensors & Controls
Accurate Flow Rate Indication with Integral Visual Confirmation. 0-10 VDC Analog Signal @ 1 mA Max. Gems ™ Sensors popularized the RotorFlow ’s ® paddlewheel design by combining high visibility rotors with solid-state electronics that are packaged into compact, panel mounting... [See More]
- Connection Type: Threaded
- Thread Size: 0.2500 to 1
- Flow Indicator Style:: Rotor
- Length (Face to Face): 2.32 to 2.95
from ERDCO Engineering Corporation
See-Flo ® Flow Indicators show you at a glance, the color, clarity and flow of liquids in process lines. An alloy vane indicator is flexed in proportion to flow through the variable area indicator housing. The large tempered glass window permits easy observation of fluid conditions and vane... [See More]
- Connection Type: Threaded; Flanged (optional feature)
- Thread Size: 0.5000 to 12
- Flow Indicator Style:: Flapper
- Length (Face to Face): 5.17 to 12
from Clark Solutions
The DG08 mechanical flow indicator is used for visual verification of the flow of liquids or gases. The liquid or gas being monitored lifts the PTFE ball from its valve seat. As the flow increases, the ball in the domed sight glass becomes increasingly visible. These devices are made of high-quality... [See More]
- Connection Type: Threaded
- Length (Face to Face): 3.1 to 4.9
- Thread Size: 0.2500 to 1.5
- Pressure Range: 0.0 to 232
from KOBOLD Instruments, Inc.
Product Features. Transparent Glass Cylinder For Liquids. Maximum Pressure 230 PSIG. Self-cleaning Mechanism for the Glass Cylinder. Universal Mountablity. KOBOLD's new DAA visual flow indicator features a self-cleaning mechanism to insure full visibility of the rotor at all times. Most types of... [See More]
- Connection Type: Threaded
- Thread Size: 0.2500 to 1.5
- Flow Indicator Style:: Rotor
- Pressure Range: 230
from LJ Star
A 360 ° full-view flow indicator with threaded connection for pipe sizes 1/2 ″ to 2 ″. The design permits observation from almost any direction under ambient light. It is equipped with an impact-deterrent shield as standard. Pressure ratings range from 100 to 150 PSI depending on... [See More]
- Connection Type: Threaded
- Thread Size: 0.1250 to 2
- Flow Indicator Style:: Plain; Drip Tube (optional feature); Full View
- Pressure Range: 100 to 150
from OPW Engineered Systems
OPW has been manufacturing sight flow indicators for over 60 years. Our experience has led to many innovations in design and manufacturing, making VISI-FLO ® the most thoroughly-engineered Sight Flow Indicator on the market. VISI-FLO ’s are available in two series: the Standard 1400... [See More]
- Connection Type: Threaded
- Pressure Range: 200 to 400
- Flow Indicator Style:: Flapper (optional feature); Rotor (optional feature); Drip Tube (optional feature)
- Material Temperature Range: -20 to 500
from Oil-Rite Corp.
Full Vision Flow Sights are used in oil lines to allow visual observation of the flow and clarity of oil. The large size of the flow sight permits maximum visibility of the oil, even from a distance. They are often used at elevated heights to tell at a glance whether oil is circulating. The valves... [See More]
- Connection Type: Threaded
- Thread Size: 0.3750
- Flow Indicator Style:: Full View
- Pressure Range: 125
from Gems Sensors & Controls
Bright Visual Flow Confirmation. Flow Ranges From 0.1 GPM to 60.0 GPM. Removable Lens for Quick Cleanout. Available in Brass, Stainless Steel or High Performance Plastic Housings. This is RotorFlow ® in its most basic form — a bright orange rotor turning with fluid flow. Simple, direct and... [See More]
- Connection Type: Threaded
- Thread Size: 0.2500 to 1
- Flow Indicator Style:: Rotor
- Length (Face to Face): 2.32 to 4.76
from ERDCO Engineering Corporation
See-Flo ® meters indicate flow rate and permit visual inspection of water, air or other transparent fluids. For general purpose industrial service, See-Flo ® meters handle a wide range of process fluids in vertical or horizontal piping runs. [See More]
- Connection Type: Threaded; Flanged (optional feature)
- Thread Size: 0.5000 to 12
- Flow Indicator Style:: Flapper
- Length (Face to Face): 5.17 to 12
from Clark Solutions
The DG06 flow indicator allows visual and quantitative monitoring of liquid flows. The device has two large glass panes – one on each side – and each with a scale attached. A stainless steel flap mounted in the flow chamber is lifted when there is flow and the current flow rate is... [See More]
- Connection Type: Threaded
- Thread Size: 0.2500 to 2
- Flow Indicator Style:: Flapper
- Length (Face to Face): 3.74 to 8.66
from KOBOLD Instruments, Inc.
Product Features. Clearly Visible Flow Indication. Low Minimum Indicated Flow. Rotatable Even in Operation. Applicable with a Large Variety of Media. KOBOLD'S DAF paddle wheel flow indicator is recommended whenever optical flow indication (no flow measurement) is required. The construction of the... [See More]
- Connection Type: Threaded
- Thread Size: 0.1250 to 1.75
- Flow Indicator Style:: Rotor
- Pressure Range: 145 to 235
from LJ Star
Standard Inline Flow-Indicator Sight Glass with Threaded Connection. The most common style of flow indicator for industrial application allows visual observation of process flow through a pair of sight glasses mounted on a casted metal body. [See More]
- Connection Type: Threaded
- Thread Size: 0.5000 to 2
- Flow Indicator Style:: Plain; Flapper (optional feature); Rotor (optional feature); Drip Tube (optional feature)
- Pressure Range: 150 to 300
from OPW Engineered Systems
OPW's 1600 Series Sight Flow Indicators are manufactured of quality materials and safety tested to assure long, dependable service at economical prices. Good for monitoring critical fluid flow, lubricant, coolant lines and sprinkler systems. Standard Features. Brass construction. Single and double... [See More]
- Connection Type: Threaded
- Thread Size: 0.1250 to 2
- Flow Indicator Style:: Rotor
- Pressure Range: 125
from Oil-Rite Corp.
Full Vision Flow Sights are used in oil lines to allow visual observation of the flow and clarity of oil. The large size of the flow sight permits maximum visibility of the oil, even from a distance. They are often used at elevated heights to tell at a glance whether oil is circulating. The valves... [See More]
- Connection Type: Threaded
- Thread Size: 1.25
- Flow Indicator Style:: Full View
- Pressure Range: 125
from Gems Sensors & Controls
Accurate Flow Rate Indication with Integral Visual Confirmation. 4.5 to 24 VDC Pulsed Output. Gems ™ Sensors popularized the RotorFlow ’s ® paddlewheel design by combining high visibility rotors with solid-state electronics that are packaged into compact, panel mounting housings. [See More]
- Connection Type: Threaded
- Thread Size: 0.2500 to 1
- Flow Indicator Style:: Rotor
- Length (Face to Face): 1.37 to 2
from Clark Solutions
DG10 sight glasses are used to visually monitor the flow of liquids in pipe systems. Depending on the type of liquid and flow volume, these devices are used with a fully clear bore or with a flap or rotor (for transparent liquids). DG10 sight glasses permit reliable monitoring of the function and... [See More]
- Connection Type: Threaded
- Thread Size: 0.2500 to 2
- Flow Indicator Style:: Plain (optional feature); Rotor (optional feature)
- Length (Face to Face): 3.94 to 9.06
from KOBOLD Instruments, Inc.
Product Features. No Features Available [See More]
- Connection Type: Threaded
- Pressure Range: 230
- Flow Indicator Style:: Rotor
- Material Temperature Range: 176
from Oil-Rite Corp.
Full Vision Flow Sights are used in oil lines to allow visual observation of the flow and clarity of oil. The large size of the flow sight permits maximum visibility of the oil, even from a distance. They are often used at elevated heights to tell at a glance whether oil is circulating. The valves... [See More]
- Connection Type: Threaded
- Thread Size: 1
- Flow Indicator Style:: Full View
- Pressure Range: 125
from Gems Sensors & Controls
Combines Visual Confirmation of Flow with Dynamic, Electronic Switch Operation. Easy, Adjustable Switch Point Calibration: a Local LED Signals When Setpoint is Reached. RotorFlow ® Switches build an extra level of reliability and protection into your equipment. By principle of operation, the... [See More]
- Connection Type: Threaded
- Thread Size: 0.2500 to 1
- Flow Indicator Style:: Rotor
- Length (Face to Face): 2.32 to 2.95
from Clark Solutions
The DG02 mechanical flow indicator is used for visual verification of liquid flow. The rotational speed of the rotor is proportional to the liquid flow rate. The domed sight glass allows the rotor to be easily seen at any time. These devices are made of high-quality materials, allowing them to be... [See More]
- Connection Type: Threaded
- Thread Size: 0.2500 to 1
- Flow Indicator Style:: Rotor
- Length (Face to Face): 3 to 3.5
from KOBOLD Instruments, Inc.
Product Features. No Features Available [See More]
- Connection Type: Threaded
- Pressure Range: 230
- Flow Indicator Style:: Rotor
- Material Temperature Range: 176
from Oil-Rite Corp.
Full Vision Flow Sights are used in oil lines to allow visual observation of the flow and clarity of oil. The large size of the flow sight permits maximum visibility of the oil, even from a distance. They are often used at elevated heights to tell at a glance whether oil is circulating. Liquid flows... [See More]
- Connection Type: Threaded
- Thread Size: 1.25
- Flow Indicator Style:: Full View
- Pressure Range: 125
from KOBOLD Instruments, Inc.
Product Features. No Features Available. KOBOLD's DKB flow indicator is ideal for use in either air or fluid flow applications. The absence of wear components assures high reliability in installations unsuitable for indicators using bearings with a rotating wheel or turbine. The DKB is easily seen... [See More]
- Connection Type: Threaded
- Pressure Range: 85
- Thread Size: 0.1250 to 1
- Material Temperature Range: 250
from Oil-Rite Corp.
Full Vision Flow Sights are used in oil lines to allow visual observation of the flow and clarity of oil. The large size of the flow sight permits maximum visibility of the oil, even from a distance. They are often used at elevated heights to tell at a glance whether oil is circulating. Liquid flows... [See More]
- Connection Type: Threaded
- Thread Size: 1
- Flow Indicator Style:: Full View
- Pressure Range: 125
from KOBOLD Instruments, Inc.
Product Features. Horizontal Installation. Highly Visible. Economical. The DKF flow indicator is best suited to fluid flow applications requiring flow indication which can be easily seen from an elevated position. Our domed sight glass allows full 360 ° visibility from above. The bright paddle... [See More]
- Connection Type: Threaded
- Pressure Range: 85
- Flow Indicator Style:: Rotor
- Material Temperature Range: 250
from Oil-Rite Corp.
Full Vision Flow Sights are used in oil lines to allow visual observation of the flow and clarity of oil. The large size of the flow sight permits maximum visibility of the oil, even from a distance. They are often used at elevated heights to tell at a glance whether oil is circulating. Liquid flows... [See More]
- Connection Type: Threaded
- Thread Size: 0.2500
- Flow Indicator Style:: Full View
- Pressure Range: 30
from Oil-Rite Corp.
Over Flow Sights are used in oil lines to allow visual observation of the flow and clarity of the oil. They are often used on large ring oil or reservoir type bearings of steam turbines or gear boxes, but can be used for many other applications. Over Flow Sights are used with low pressure. The... [See More]
- Connection Type: Threaded
- Body Materials: Other; Acrylic
- Thread Size: 0.7500
from Oil-Rite Corp.
Over Flow Sights are used in oil lines to allow visual observation of the flow and clarity of the oil. They are often used on large ring oil or reservoir type bearings of steam turbines or gear boxes, but can be used for many other applications. Over Flow Sights are used with low pressure. The... [See More]
- Connection Type: Threaded
- Body Materials: Other; Acrylic
- Thread Size: 1