A see-through glass tube or window mounted in a tank or boiler system, the sight glass allows you to see and monitor what is inside of the container or vessel to ensure safety and optimum quality. This function makes sight glasses critical in ensuring smooth and safe operation, regardless of the application.

The sight glass, also known as sight glass window, is particularly useful in keeping tabs of fluids in a pipe system and pressure in boilers. In a heating system, the sight glass is used to monitor the condition of heating elements and pilot lights. Sight glasses are commonly used in different industries, including pharmaceuticals, wastewater treatment and management, biofuels, automotive, and many more.

Common Types of Sight Glasses

The sight glass moniker is often applied to different components that allow users to observe the level or condition of fluid inside a tank, pipe, or vessel. Below are the various items commonly referred to as sight glasses:

• Circular Sight Window

The typical sight windows are circular. It looks like a ship's port window and is directly installed onto the vessels and tanks' sidewalls for an unobstructed view of the interior and contents.

• Liquid-level Gauge

The liquid-level gauge is designed for easier monitoring of the fluid level in a tank or vessel. This type of sight glass is popular in automotive, trucking, and other industries with storage tanks or containment systems. 

Some liquid-level gauges are equipped with glass on two opposing sides and lights positioned at the back portion to help the viewer see what's happening inside. Others use a single-sided unit with a slotted "reflex" gauge glass, which makes the gas/liquid boundary easily identifiable in low-light conditions. 

• Fused Sight Glass

A subset of the circular type, the fused sight glass has the lens and the metal ring fused at high temperatures to form one discrete unit. The glass fitted into this unit has a lower thermal expansion coefficient than the metal ring. After the glass is melted into the metal ring, the metal ring's contraction inflicts bulk compression on the glass, therefore increasing its bulk strength.

• Sight Flow Indicator

This type of sight glass aids with the observation of fluids that move through a pipe, hence the term 'flow indicator'. It is composed of a tubular glass sandwiched by two flanges using long threaded rods. This type of sight glass enables users to inspect fluid from any angle. However, sight-flow indicators are not ideal for high-pressure applications as their use is limited to the tensile strength of the tubular glass.

Factors to Consider When Choosing a Sight Glass

To ensure optimal performance and service life from the new sight glass, you need to consider the following factors before purchasing:

• Material 

The materials used in making sight glass for automotive applications differ per part. The glass part can be made of transparent glass, acrylic, polycarbonate, or a combination of glass-ceramic materials. The body, on the other hand, is commonly made of carbon steel and stainless steel.

When getting one, you should go for the material that offers superb optical quality and remarkable resistance to temperature changes, impacts, prolonged exposure to damaging elements, and the rigors of regular use.  

• Pressure

When buying a new sight glass, always consider the pressure capabilities of the entire assembly. This is often determined by the glass material, glass thickness, and the unsupported diameter. 

• Mode of installation 

The sight glass can be installed in three ways: 

1. Weld-on. If the sight glass is welded into place, make sure that the sight glass hole's size matches the vessel into which it will be welded into.  
2. Bolt-on. For a bolt-on sight glass, see to it that the existing bolt holes match the holes of the flange the sight glass will be bolted into. Take note also of the pressure limitations of the flange type used.
3. Clamp-on. This type of sight glass is commonly used in the pharmaceutical industry as it can easily be disassembled for cleaning.  

What Makes the Alemite Sight Glass with Snap Valve Different?

The Alemite Sight Glass is manufactured by a company that is backed by 100 years of product excellence. It is made from clear, acrylic material and is designed to make visual checking of condensed oil an easy feat. The Alemite sight glass is fitted with a brass snap valve that allows quick draining of fluid and closes when released.

Ideal for use on both manifold blocks and bearing housing drains, this sight glass includes a ½-inch NPT(m) adapter. This adapter provides a solid attachment point between the sight glass and aluminum manifold blocks. 

Here are the other factors that make this clear acrylic sight glass outperform the competition:    

• Excellent optical clarity. The transparent acrylic material is a practical glass alternative as it offers glass-like brilliance, clarity, and transparency. It also boasts superior weathering properties than other transparent plastics.
• Good impact and chemical resistance. This sight glass stands up to high levels of stress for short periods and is among the most scratch-resistant thermoplastics.
• Outstanding corrosion resistance. Acrylic resists years of exposure to corrosive and abrasive elements without losing its surface gloss, transparency, and shape. 
• Lightweight. This sight glass is durable yet lightweight, so it will not add significant weight to your vehicle. 

Where to Buy the Alemite Sight Glass with Snap Valve Online? 

The sight glass is not among the vehicle's wearable components, so it may take you a while to replace the stock component in your fleet. But if the inevitable happens and you find yourself looking for a new one, don't think twice in getting it from FinditParts. We carry a wide range of top-quality Alemite products, including your needed Sight Glass with snap valve. Visit our site now and discover our low prices, reasonable shipping rates, and best deals especially for bulk purchases. We are open to serve you 24/7, so you can place your order at your most convenient time.