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    BCST your Sight Glass Valve Supplier

    BCST sight glass valve is a kind of indicator for flow or level  , an apparent tube thru which the operator of a tank , pipe or boiler can look at the quantity of liquid contained within. Often called sight viewing glasses, they offer you a way to appearance the flow or levels of liquids or gases which may be passing thru the essential parts of your design, and sincerely something else that sight glass windows additionally need to allow you to.

    With their super use, sight glass valves have turn out to be vital to operations such as steam pipelines, chemical processing, food processing, steam boilers, pharmaceutical industries, and beverage industries. Beyond the one application, sight glass valves are beneficial anywhere that you chose to see the appearance of your equipment.

    BCST your One-Stop Sight Glass Valve Manufacturer

    Double window sight glass valve

    Double Window Sight Glass Valve

    Paddle Wheel Sight glass valve

    Paddle Wheel Sight Glass Valve

    Sanitary Sight Glass Valve

    Thread Sight glass valve

    Thread Sight Glass Valve

    tubular sight glass valve

    Tubular Sight Glass Valve

    Wheel Sight Glass Valve

    BCST your BEST Sight Glass Valve Supplier

    BCST is one amongst the leading reliable and stable sight glass valves manufacturers in China. If you’re searching for an experienced manufacturer for your next project, with strong technical background, professional team, and budget-friendly products, BCST is your most suitable choice.

    BCST can provide different products supported customers’ requests. From packaging to delivery, you’ll receive BCST’s most detailed service. BCST’s technical team will provide you with professional guidance during usage or installation. With ATEX, ISO, SIL2, RoHS, and CNEX, BCST will provide you high-quality sight glass valves at a competitive price.

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    BCST Quality Control For Sight Glass Valve

    • Technical software caculation
    • Technical team meeting
    • CAD drawing confirmation  


    • Installation
    • Calibration
    • Chemical Analysis
    • Mechanical Propery
    • dimension Checks
    • Visual Checks
    • Non-destruction Examination

    Hydrostatic Test

    • Shell test
    • Sealing test
    • Leakage test
    • Air test
    • Function test
    • CNC machining
    • Visual checks
    • Dimensional checks
    • Liquid penetration test

    Outlook Treatment

    • Surface Polish
    • Painting
    • Visual inspection
    • Thickness checks
    • Visual checks
    • Liquid penetration
    • Test
    • Hardness test
    • Lapping
    • Dimensional checks


    • Marking
    • Exported wooden box

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    BCST Sight Glass Valve Application

    Sight Glass Valve -FAQ

    What are different types of sight glass valves?

    A sight glass valve is used to see the liquid inside a tank or machine. These sight glass valves are available in two different forms, the first one is a bullseye, and the other is columnar. You can use them to check the oil or water level in the tank. Sight glass valves help you monitor the liquid without opening the machine, making the procedure safe.

    You can mount a columnar sight glass valve outside the tank, which is unprotected. On the other hand, the bullseye sight glass valve has no drawbacks, but sometimes they do not give you appropriate reading.

    So let’s see what different types of sight glass valves are.


    It has a specific installation method. You can install a bullseye sight glass valve in the tank by making a hole on the top. Then the sight glass is joined on to the spot, and it appears as a bolt with a glass head. Some bullseye sight glass valves have a glass line showing the liquid level when the equipment is working. This sight glass valve helps you to notice foaming in your system. And you can diagnose the problem and stop severe damage.

    Bullseye Sight Glass Valve

    Columnar sight glass valve:

    This kind of sight glass valve is composed of vertical tubes mounted outside the tank. With the help of a columnar valve, you can see a more considerable amount of liquid than the bullseye sight glass valve. These sight glass valves are attached near the bottom of the tank, where they can be damaged. Another problem that can occur is they don’t show the foaming problem.

    The benefit of a columnar sight glass valve is that you can mark the correct liquid level for the machine when working or idle.

    BS and W Bowls:

    BS and w is the abbreviation of bottom sediment and water. These valves sight glass valves are minor than columnar valves. These valves are also mounted at the bottom of the tank. It also includes a magnet that draws some metallic contaminants to them. As these sight glass valves are attached to the bottom of the tank, it is a huge possibility for them to get damaged.

    3D sight glass valves:

    This kind of sight glass valve is a bullseye sight glass valve. These sight glass valves are not flat but extend outward from the tank. With the help of these valves, you can view the liquid from multiple angles. Most of these sight glass valves are glass, acrylic, or polyamide. These valves can bear extreme pressure and temperature. 

    3D sight glass valves

    Multifunctional sight glass valve:

    This kind of sight glass valve has the ability you can remove their parts and easily able to clean them and inspect them.

    Why should you use a sight glass valve?

    When you use a sight glass valve, you don’t need an opening and closing system, so moisture and debris cannot enter the tank when you try to examine the process. When you notice the colour of the liquid in sight glass valve, you can see the dirt or size of contaminants inside the liquid. If you suddenly notice dirt, you must know you will face the problem. Some sight glass valve has a magnet that helps you decide if the things inside the system are standard or need to be solved.

    It’s great to check the level of the liquid in your system. A sight glass valve makes it very easy to maintain the proper amount of fluid in the tank.

    What should be the minimum water level in the boiler sight glass valve?

    The boiler always needs the proper amount of water to work correctly. If you cannot notice the minimum amount of water in the sight glass valve, you will not get the appropriate heat that you expect from the boiler. So you should maintain the water level inside the boiler.

    The water level in the sight glass valve should be the exact amount of liquid. i.e., it should show that the tank is half full, but it should not be more than three-quarters full. You should check the tank with the help of a sight glass valve and drain the tank every two weeks. So that sediment left in the tank should drain out the residue left. After that, if any dirt is left, you can notice it again with the help of a sight glass valve. If the sediment is deep in the bottom, the water will be lower because the sight glass valve will show you the exact amount of water in the boiler.

    If your system contains an automatic feeder, you can even check the water level inside the sight glass valve because the feeder cannot maintain the proper water level in your system.

    What are filter drier and sight glass valves?

    The filter drier and sight glass valve are a pair of standard fitting in liquid pipelines. The filter drier and sight glass vales are very important in fluid lines, but their importance is mainly underestimated. The function of these two is this. They protect the refrigeration system. They indicate problems that can affect the refrigerator system. It suggests the level of moisture or any. contamination in the system.

    The function of sight glass valve:

    Sight glass valve is associated with filter drier in a specific way. Sight glass valve is generally fitted in liquid line in a system with expansion valve. It is adjusted in a fluid line immediately after the filter drier. But you can adopt a sight glass valve anywhere on the liquid line, but you should keep in mind that its placing should be closed to the expansion valve.

    A sight glass valve with an indicator has two functions. It checks the moisture level of the refrigerator; it also shows that liquid refrigerant is present properly. If the moisture is ok, then the indicator’s colour turns green.

    If the sight glass valve indicator shows yellow colour, there should be some issue with moisture content in the refrigerator. Excess moisture can create icing in the expansion valve if the evaporating temperature is 0˚C. Excess water in the system can react with the oil used in a standard refrigerator, forming acid.

    The sight glass valve also shows the shortage of refrigerant in the liquid line. And you can resolve the issues related to the refrigerator after indication by sight glass valve.

    Different Forms of sight glass valves:

    Standard sight glass valves come with solder fitting and flare fitting with male threads. And also male and female fittings for direct connection to filter drier. You can also get a sight glass valve without housings for screw-in installation, and they are also available in the saddle-mount version. You can install Saddle-mount sight glass valves on large diameter pipes. And besides that, you will use suitable adopters.

    Installation of sight glass valve on solder connection:

    When you install a sight glass valve on a solder connection, you should take special care in this regard. If you use a hard-to-solder with a nitrogen blanket, you should install a sight glass valve. It will prevent scale formulation in pipe or sight glass valve. You should use nitrogen in the sight glass valve. If you ignore the use of nitrogen, then a black coating will appear on the inner surface.

    What are A/C sight glass valve diagnoses?

    You can install A/C and refrigerator sight glass valves on the pipe where liquid flows. But if you install the sight glass valve at condensing unit, it can help you in any trouble. Sight glass valves are available in two basic styles first one is plane with moisture indicator. Let’s check the plane sight glass valve with a moisture indicator. A plain sight glass valve is used to prevent the proper movement of the refrigerant. And the sight glass valve with indicator indicates the moisture level in the system. It contains a minor element that changes colour in the presence of moisture.

    What you see in sight glass valve can tell you about any problems accrued in the system. But do not use the sight glass valve for diagnoses purpose and to diagnose R134a systems.

    If you feel that the sight glass valve is precise, you must know that one of three conditions can exist. The first condition is the system is empty. The second is that the system is whole, and the third condition is that the system is overcharged. If you notice the foam, then the charge will be low, and if you notice a few bubbles, the system will be ok. It’s normal to see a few bubbles when the compressor is working. It would help if you took it as usual.

    When you feel oil streaks in the sight glass valve, the compressor is pumping oil from the sump. If you notice that the sight glass valve is cloudy, the desiccant bag might burst. If you are using the R134a system and have a sight glass valve, you should avoid using it or try to diagnose, as it is customary to notice a bubble in this kind of system.

    How to install oil sight glass valves?

    Oil sight glass valves are installed in many different ways. To understand their installation process, let’s check other installation methods.

    Standard installation:

    Bottom sediment and water bowl:

    Suppose you want to install a sight glass valve in the tank, then you should Install it at the lowest level. Generally, sight glass valves are installed on the drain port. It would be best if you used a 90˚ piping elbow. The oil sight glass valve is installed below the oil reservoir, collects water and sediments sink, and contains the insight glass valve. It is harmful to water that the user can drain.

    Horizontal oil sight glass valve:

    You can install a Horizontal oil sight glass valve into the drain port. And it will collect the harmful water and sediments from the oil. You can install a horizontal oil sight glass valve if you don’t have enough vertical space to establish a standard oil sight glass valve.

    Standard Installation of Oil Level Indicator and sight glass valve:

    The oil level indicator indicates the appropriate oil level inside the oil reservoir. There is a breather cap on the top-level indicator that maintains pressure. It has a red and green sticker, which indicates the upper and lower level. You should install it vertically.

    A horizontal sight glass valve is installed at the bottom or lower level. And because of this installation of oil sight glass valve at the lower point, you can collect all the harmful water and sediment in sight glass valve.

    When installing ate on the drain valve, you can install both the oil level indicator and sight glass valve. And after that, you will be able to check the oil level, and also you can collect water sediments.

    What are level sight glass valves?

    Tubular level sight glass valves are designed to see the liquid level. It is made up of red line borosilicate tubing to see fluid levels. All valves use a stuffing box arrangement to seal the glass tube, and they have a ball check shut off to stop loss of vessel contents if the glass fails. This kind of sight glass valve controls operating pressure and temperature. These level sight glass Valves are rated for 500 PSIG at the temperature of 450˚F. 

    level sight glass valves

    The absolute pressure limitations belong to gauge glass. You can use a level sight glass valve with water and petroleum chemicals. Check your liquid compatibility with Buna seal materials.

    Tubler sight glass valves

    Who are the manufacturers of sight glass valves?

    China and India are top countries sight glass valve manufacturing countries. And when you talk about China, BCST is a top-ranking manufacturer and supplier of sight glass valves. The company is supplying sight glass valves to more than 100 countries globally.

    The sight glass valve is a unique instrument made by the company. It monitors the liquid level and contamination in the tank or boiler.

    It helps the user maintain the smooth flow of liquid and the whole system’s capability. So if you want to keep the liquid level, monitor its working, and solve the issues related to your system, you need a sight glass valve for this purposeSight glass valve fulfils your industrial needs. It helps you check the level of water or oil and drain out contamination from it.

    What are the things to consider while determining the best sight glass valve for your application?

    You should keep in mind the following points if you want to determine the best sight glass valve for you:

    Maximum temperature:

    You should select a sight glass valve according to your needs. Standard soda-lime sight glass valves are only suitable for the systems which need 300˚F.

    And if you are working at a high temperature, you should use borosilicate glass or quartz glass in your sight glass valves.

    Thermal shock in sight glass valve:

    When using sight glass valves at variable temperatures, you should use the sight glass valve with a material that can tolerate high or low temperatures. Using a sight glass valve made of borosilicate glass would be best. On the other hand, a plastic sight glass valve can sometimes handle temperature changes because of the material’s elasticity.

    Corrosion in sight glass valve:

    Sometimes acidic liquids affect the site glass valve, and it becomes cloudy. And this condition hinders its transparent look. It would help if you chose the sight glass valve with a material that can tolerate corrosive influence.

    Abrasion in sight glass valve:

    You should select a sight glass valve that may be composed of material that cannot get any effect of abrasion. You should check the sight glass valve visually or with ultrasonic equipment.

    Sight glass valve and pressure:

    It would be best to use fuse- a type sight glass valve in a high-pressure application to avoid glass failure.

    Impact of application on sight glass valve:

    Some items like food processing may impact against sight glass valve. If you see any scratches on the sight glass valve, you should replace it.

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