The Purpose of a Diesel Fuel Inline Sight Glass

The purpose of a diesel fuel inline sight glass is to enable a mechanic to see how much fuel flows through the line. The fuel passes through the support head 12 and into bore 115, which flows against the glass 125. The sight glass is attached to a casing 110, which may have a bolt head on the closed end or external threads, which makes it easy to change the sight glass 100.


There are two types of sight glasses used in the diesel fuel industry. A bullseye sight glass is a variation of a flat sight glass used in oil tanks. Its design provides multiple views and allows light to penetrate the oil, allowing inspectors to see if there are any contaminants present. The bullseye sight glass is generally made of glass, polyamide, or acrylic. The bullseye sight glass is also helpful in detecting foaming in the fuel system, which is a sign of contamination.

The third type of sightglass is a 3-D version of a bullseye sightglass. A 3-D version allows a viewer to view oil levels in 360 degrees. Traditional sight glass made from brass is easily stained and difficult to see. Modern sight glasses make it easy to see the exact amount of oil inside an oil tank.

The durability of diesel fuel inline sight glass varies greatly, so check the specifications and ratings before purchasing. The most critical factors are thermal ratings, chemical resistance, and durability.


A columnar diesel fuel inline sight glass is an excellent way to monitor the fuel level in your diesel fuel tank. The sight glass features a clear body and 1-inch NPT threads on each end. It also includes a 3-micron breather. The sight glass also features tamper-proof level rings. These rings are made of a durable polycarbonate material called TritanTM.

Columnar sight glasses do not show foam. Because the oil entering a columnar comes from the bottom of the sump, you don’t have to worry about the sight glass being scratched or dented. A columnar sight glass also lets you check your oil level when running or idling.

Despite its superiority over bullseye sight glasses, columnar sight glasses can be more challenging to install. In addition, since they draw their oil from the bottom of the tank, columnar diesel fuel inline sight glasses are more expensive than bullseye sight glasses. Regardless of how you install the sight glass, it is essential to know that it is installed correctly to give accurate readings.


If you want to check the oil level in your diesel engine, you should use a sight glass. A sight glass shows the level of oil and contaminants in the oil. In addition, some magnets help you determine if your oil is dirty or has metal fragments.

Sight glasses are generally available in cross-type, inline, and tank. Stainless Products manufactures cross-type and inline sight windows for a variety of applications. Most are 3-A certified, come apart for easy cleaning, and are available with borosilicate glass viewports for various applications.

Fixed-type diesel fuel inline sight glass, also known as a fuel level gauge, allows for observing the liquid level in a diesel fuel tank. In addition to checking liquid status, modern industrial sight glasses can be used to monitor several other features. As a result, these devices are suited for various applications, including liquid-free processes.


An Acrylic diesel fuel inline sight glass is a manufactured item used for checking the grade of diesel fuel. It fits between standard tank truck flanges, enabling operators to see the fuel grade without opening the valve. It is made from a cast acrylic sheet machined to achieve optical clarity. It can operate in temperatures up to 65degC and has a pressure rating of 150 PSI.

These sight glasses are available in three and four-inch sizes. They feature durable cast aluminum housing and are suitable for use with diesel, gasoline, and ethanol blends. They also offer a minimum-level switch.

An inline sight glass can be inexpensively manufactured and has several advantages. For example, it enables a truck operator to check the fuel level from a distance visually and prevents them from discharging the wrong fluid.