The industrial pipelines, tanks, and vessels can have their processes visually inspected thanks to the sight glasses made by PresSure Products Company. Our sight windows are made to overcome the major drawbacks of similar designs, giving consumers a readily maintained installation with substantial safety margins, unlike most other units, which just have a piece of glass sandwiched between two metal flanges.

Custom safety sight glasses can be made to match your exact needs, and the majority of our items have Factory Mutual approval.

Call (800) 624-9043 to place an order for any of the standard models listed below. Click on any item to view the product description, engineering specifications, construction materials, and unit image.

How does Sight Glass Works?

Let’s consider the water level indicator in a coffee maker. While not always visible from the outside like a traditional sight glass, it serves a similar purpose by providing a visual indication of the water level inside the coffee maker’s reservoir.

Here’s how it works:

Many coffee makers have a small transparent window or markings on the side of the reservoir, indicating the water level.

As you fill the reservoir with water, the level rises, becoming visible through the indicator window. Users can see at a glance how much water is available for brewing.

Instead of guessing the water level or needing to open the reservoir, users can simply look at the indicator window to know when it’s time to refill.

This feature ensures that users always have enough water to make coffee without overfilling or running out unexpectedly, allowing for smooth and uninterrupted brewing.

In this example, the water level indicator in a coffee maker demonstrates how sight glass principles are applied in everyday appliances, offering a practical and convenient way to monitor fluid levels for optimal usage.

TYPES OF SIGHT GLASS

A sight glass is like a window into a closed container or pipeline, allowing you to see what’s inside without opening it. It’s often made of transparent glass or plastic and is installed directly into the wall of the container or pipeline. Imagine it like a window on the side of a house, but instead of looking outside, you’re peering into a tank, pipe, or vessel.

When there’s liquid or gas inside the container or flowing through the pipeline, you can see it through the sight glass. This visual access helps operators monitor levels, flow rates, and conditions without needing to physically open the system, which could be dangerous or disruptive.

For instance, in a chemical plant, workers can use sight glasses to check if the right chemicals are at the correct levels. In food processing, they can ensure that liquids are flowing smoothly without contamination. It’s a simple but crucial tool for maintaining safety, efficiency, and quality control in various industries where being able to see what’s happening inside a closed system is essential.

Model L Sight Glass

For the majority of sight window applications, Model L is one of our most affordable options. Available with a single piece or laminated two piece lens, 150 PSI class ANSI B16.5 flange connection or weld pad connection, and pressure ratings of 100 or 150 PSI.

Model L- Flange Sight Glass

Materials of Construction:

Flange: 316 or 304 Stainless Steel SA-182; Carbon Steel SA-105
Lens: Two-Piece Laminated Tempered Soda Lime (standard); Tempered or Annealed Borosilicate; Polycarbonate and Acrylic.
Lens Cushion Gaskets: Teflon®; Grafoil®; Gylon®; Blue-Gard®; etc.
Seal: Teflon®; Viton®; Silicone (all standard); EPDM and others (special order).

The Model L Flange is designed to meet pressure requirements from full vacuum to 100 psi while maintaining the safety of PresSure Products’ higher-pressure and temperature units. The Model L Flange unit accommodates typical 150 psi ANSI B16.5 (2″ to 8″) flanges and can withstand temperatures up to 450ºF. The wetted components are the seal, the bottom cushion gasket, and the glass lens, which are kept in place by either a carbon steel or stainless steel flange. The unit can be equipped with a silicone, Viton®, Teflon®, or EPDM seal, and various construction materials are available to fulfill your process requirements.

Applications needing DIN standards or non-ANSI flanges are available upon request; no metal parts come into contact with the process, so no mating gaskets are necessary.

Model L- Weld Sight Glass

Materials of Construction:

Body: 316 or 304 Stainless Steel SA-351 or SA-240; Carbon Steel PVQ and SA-516 Grade 70; Hastelloy; Alloy 20; Titanium; Monel; etc.
Retainer Cap: 316 or 304 Stainless Steel SA-351; Carbon Steel PVQ.
Lens: Two-Piece Laminated Tempered Soda Lime (standard); Tempered or Annealed Borosilicate; Polycarbonate and Acrylic.
Lens Cushion Gaskets: Teflon®; Grafoil®; Gylon®; Blue-Gard®; etc.
Seal: Teflon®; Viton®; Silicone (all standard); EPDM and others (special order).
Retainer Cap Bolts: 18-8 Stainless Steel; Carbon Steel SA-193

With the safety of PresSure Products’ higher pressure units, the Model L Weld is designed to meet pressure requirements from complete vacuum to 100 psi. This device is intended to be welded to either new or old equipment, or it can be integrated into a pipeline system, manway cover, vessel wall, or vessel head. It can be ordered with the weldment shaped to match a particular radius, either spherical or cylindrical. The device is suited for temperatures up to 450ÂºF and is made for sizes ranging from 2″ to 8″.

The Model L Weld can be used with buttweld, socket-weld, pipe thread, or sanitary connections and comes with a silicone, viton®, Teflon®, or EPDM seal. It is possible to get units with an integrated spray ring or wiper.

Model B Sight Glass

With the ability to meet higher pressure and temperature requirements that other designs cannot, Model B is the most adaptable sight window available. Accessible in both weld pad connection and flange connection (ANSI B16.5 class 150, 300, or even higher, as well as other customized flanges).

Model B- Flange Sight Glass

Materials of Construction:

Flange: 316 or 304 Stainless Steel SA-182; Carbon Steel SA-105
Retainer Caps: 316 or 304 Stainless Steel SA-351; Carbon Steel SA-519
Compression Ring: 304 Stainless Steel SA-351; Carbon Steel SA-519
Lens: Two-Piece Laminated Tempered Soda Lime (Standard); Tempered or Annealed Borosilicate; Quartz; Lexan; Acrylic; Mica Shields
Lens Cushion Gaskets: Teflon®; Grafoil®; Gylon®; Blue-Gard®; etc.
Lens Packing: Combination Teflon® Impregnated and Viton® (Standard); Graphite; FDA Teflon®; etc.
Compression Screws: 18-8 Stainless Steel; Carbon Steel SA-193

The threaded lens retainer cap-equipped Model B flange unit is designed to fit into typical ANSI B16.5 (2″ to 24″) flange accommodations. Different building materials are available to satisfy your process needs, and units can be constructed to match your pressure and temperature requirements. Applications needing non-ANSI flanges or DIN specifications can be provided upon request.

Model B- Weld Sight Glass

Materials of Construction:

Lens Cushion Gaskets: Teflon; Grafoil; Gylon; Blue-Gard; etc.
Lens: Two-Piece Laminated Tempered Soda Lime (Standard); Tempered or
Annealed Borosilicate; Quartz; Lexan; Acrylic; Mica Shields
Body: 316 or 304 Stainless Steel SA-351 or SA-240; Carbon Steel PVQ; Hastelloy; Alloy 20; Titanium; Aluminum; etc.
Lens Packing: Combination Teflon Impregnated and Viton (Standard); Graphite; FDA Teflon; etc.
Compression Ring: 304 Stainless Steel SA-351; Carbon Steel SA-519
Lens Cushion Gaskets: Teflon; Grafoil; Gylon; Blue-Gard; etc.
Retainer Cap: 316 or 304 Stainless Steel SA-351 or SA-240; Carbon Steel PVQ; Hastelloy; Alloy 20; Titanium; Aluminum; etc.
Retainer Cap Bolts: 18-8 Stainless Steel; Carbon Steel SA-193
Compression Screws: 18-8 Stainless Steel; Carbon Steel SA-193

The Model B Weld unit, with its bolt-down lens retainer cap, is designed for adaptation to new or existing equipment to become an integral part of a vessel shell, vessel head, manway cover or in a pipeline system. It is available with the weldment contoured to fit a specific radius (cylindrical or spherical) and can be mounted flush with the interior or directly to the outside of the vessel shell. The unit may be designed in sizes from 2 to 24.” Units may be manufactured to meet your requirements for pressure and temperature, as well as the different types of construction that are available in order to respond to your process needs.

The Model B Weld can be utilized with other types of connections including butt-weld, socket-weld, pipe thread, or sanitary. The built in spray ring or wiper may be provided for the units.

Model I Sight Glass

Model I is an economical design for service in aggressive chemical environments that require very corrosion resistant (and expensive) metals. This design minimises the use of expensive materials, while meeting the necessary corrosion resistance and high temperature and pressure characteristics of Model B through the inclusion of an insert that separates the wetted area from a large portion of Structural Metal.

SANITARY SIGHT GLASS & FITTINGS

Pressure Products Company offers an extensive array of sanitary fittings and sight glasses with sanitary connections. Sanitary/tri-clamp connections reduce the likelihood of bacterial contamination for food and drug industry processes and are valued in other industries for their convenience.

General sanitary fittings and components are offered in 304 and 316 stainless steels. Sanitary sight glasses, sanitary flow indicators, and other custom items with sanitary connections are usually made of 300 series stainless steel. Other materials are available by request.

SIGHT FLOW INDICATORS

Pressure Products Company’s sight flow indicators are used in piping to provide 360-degree observation of material flow through a line. A typical configuration consists of two circular sight glasses positioned perpendicular to the direction of the flow and opposed to one another.

Our sight flow indicators reflect the advantages of our sight glass designs, namely the ease of sealing, maintenance, and availability in higher pressure/temperature combinations in larger sizes than any other manufacturer offers in the industry.