Sight flow indicator is a device installed in the pipe & which provides a means of verifying the flow direction & the approximate flow. The ability to see what is happening inside the pipe is very useful for the process operators. This is a very simple & cost effective device & provides a means to the operators to observe color & clarity of process fluids through the window.
This may or may not have passive components which are set in motion by the direction of flow. Thus, giving the operator an idea of flow direction & also the approximate estimate of flow intensity.
Flow indicators without indication components are used wherever observing the flow characteristics is more important than verifying the flow rate.
This is also called as 360 deg. Sight flow indicator / Tubelar type sight flow indicator, since it allows the operator to view the fluid from any angle. This can be installed in any position to observe the flow in any direction.
It is particularly suitable for low pressure systems with moderate flow rates. Care should be taken that this type of SFI shall be installed in the pipe where there is low mechanical strain.
This is available from 1” to 4” size. The materials shall be suitable for the fluid. The glass used shall be selected based on the operating temperature. Soda lime glass can be used upto 150 deg. C & Borosilicate glass upto 300 deg. C.
This type of indicator has 02 opposing windows so that the operator can see the intervening fluid lightened from behind either by ambient light or any other means. This is named as plain as it does not have any flow indication devices. Unlike full view type, this can be used at high pressure, high temperature application & harsh fluid applications.
Double window type sight flow indicator, can be supplied in flanged end connection OR socket weld connection OR butt welded end connection, as per requirement.
Line sizes of 1” to 12” are covered in by this type with 150# & 300# pressure rating. Material selection will be as per the fluid flowing inside. PTFE coating can be provided as per requirement of process.
Flow indicator when fitted with a hinged flapper visible through the sight glass, is called as SFI with flapper type indicator. When there is a flow, the flapper deflects in the direction of flow & remains at zero position when there is no flow.
With the position of flapper, the operator can have an approximate gauge of flow rate, since the flapper position is directly proportional to the force due to flow rate. This style is best suited for horizontal pipelines but may also be used in vertical pipelines with flow in upward direction. For downward flow direction, flapper type SFI is not suitable.
Typical applications of the indicator are found for flow of transparent solutions OR gas flow OR dark fluids for which it is difficult to observe the flow. These are useful for the flow in one direction only. Other details are similar to double window plain type sight flow indicator.
Flow indicator when fitted with a rotor or impeller that is turned or rotated with the flow rate, is called as SFI with rotary indicator. The rotors are mounted inside the indicator such that the operator can observe the direction & approximate speed of flow.
Similar to flapper type indicator, this finds its application in flow of transparent solutions OR gases OR even dark fluids.
This is advantageous over flapper type indicator in the way that it can be used for both horizontal as well as vertical pipeline with flow in any direction. This can also be used with bidirectional flow. It is not advisable to use at very low flow, because the rotor may not rotate at lower flow rates. All other details are same as double window plain type sight flow indicator.
This is a special type of sight flow indicator, designed for the drip observation. Drips & low volume intermittent flow can be observed with the help of this type of sight flow indicator. Typically this is used in distillation OR condensation application.
Since the gravitational effect is the basis of its design, this type is used only in applications where the flow is vertically downwards. All other details are same as double window plain type sight flow indicator.
In this type of sight flow indicator, a ball or number of balls are used as an indicator. The bass is clearly visible through the window & thus the flow direction can be predicted. Suspension of balls in the fluid indicates the flow & in the absence of flow rate the balls are in the rest position.
Again the concept of gravity is used for this type also & hence it is used for the flow in vertically upward flow only. Typically it is used for lower line sizes with slow flow & not for high flow rates. Line sizes may be ¼” to 1.5” & the end connection may be threaded or socket welded. For better identification, the balls used may be with different colors rather than one color. We are specialised in sight flow indicators in India