When it comes to high-pressure industrial systems, sight glasses are more than just viewing windows—they’re mission-critical safety components. Selecting the wrong type can result in leaks, system failure, or even injury. At Electro-Seal, we manufacture high-performance custom sight glasses designed to withstand extreme pressure, temperature, and chemical exposure.
In this guide, we’ll walk you through how to choose the right sight glass for your high-pressure system—based on material, mounting, sealing method, and pressure rating.
What Is a Sight Glass and Why Does Pressure Rating Matter?
A sight glass is a transparent component installed in piping, tanks, or pressurized vessels to allow visual monitoring of liquids or gases. In high-pressure systems, these components must maintain visibility without compromising safety or structural integrity.
If a standard or improperly specified sight glass is used under high pressure, it can shatter or leak—resulting in equipment downtime or catastrophic failure.
That’s why high-pressure applications demand engineered glass materials, secure metal housings, and hermetic sealing techniques like those used in Electro-Seal’s fused glass-to-metal products.
- Determine Your System Pressure Requirements
The first step is to determine your system’s maximum operating pressure and peak pressure events. For example:
- Low pressure (<100 psi): Standard soda-lime glass may be sufficient.
- Medium pressure (100–600 psi): Borosilicate glass in compression-sealed housing is ideal.High pressure (600+ psi): Fused glass-to-metal seals and specialty alloys become essential.
Electro-Seal specializes in custom sight glasses built to withstand well over 1,000 psi, depending on configuration.
- Choose the Right Glass Material
Glass strength is a critical consideration. Common options include:
| Glass Type | Max Temp | Pressure Use | Notes |
| Soda-Lime | ~300°F | Low | Budget-friendly, not for high temp/pressure |
| Borosilicate | ~500°F | Medium | Chemical resistant, stronger than soda-lime |
| Fused Quartz | ~1,000°F | High | Ultra-resistant to heat and thermal shock |
| Sapphire | >1,200°F | Very High | Extreme strength but costly |
Electro-Seal typically uses borosilicate or fused quartz glass, depending on customer needs. We also offer guidance for chemical compatibility.
- Select a Secure Mounting Style
For high-pressure applications, you’ll want to avoid bolted or gasketed installations, which may loosen or degrade under pressure. Instead, consider:
Fused glass-to-metal seals
- Fully hermetic
- Ideal for extreme pressure and corrosive environments
- Manufactured with matched expansion metal alloys (e.g., Kovar or stainless steel)
Compression sealed housings
- Metal surrounds that compress the glass under pressure
- Effective and serviceable, but not fully hermetic
Electro-Seal manufactures fused, leak-proof sight glasses ideal for mission-critical applications.
- Consider Operating Environment & Media
Ask these key questions:
- What chemicals or fluids will the sight glass be exposed to?
- What is the temperature range (operating and ambient)?
- Is the environment corrosive, abrasive, or high-vibration?
For example, hydrocarbon processing and steam service often require high-pressure, corrosion-resistant materials. That’s where Electro-Seal’s custom stainless steel housings and treated glass come into play.
- Determine Size, Shape & Custom Features
Standard sizes don’t always meet real-world conditions. Electro-Seal offers:
- Custom shapes (round, rectangular, multi-port)
- Anti-glare or frosted finishes
- Engraved ID marks or serial numbers
- Optional liquid level indicators integrated with the glass
Need help with a special design or retrofit application? We can manufacture to spec or reverse-engineer from existing parts.
Common Applications for High-Pressure Sight Glasses
- Oil & gas systems
- Chemical processing tanks
- Steam lines and boilers
- Aerospace and defense assemblies
- Agricultural sprayers and pressure vessels
We frequently manufacture parts for OEM tractor equipment, industrial instrumentation, and fluid monitoring systems nationwide.
FAQs: Choosing a Sight Glass for Pressure Systems
Request a Custom Sight Glass from Electro-Seal
Whether you’re designing a new system or upgrading a legacy one, Electro-Seal is your trusted source for precision-engineered, high-pressure sight glasses.
✅ USA-manufactured
✅ Built to exact specs
✅ Reliable under pressure
Call Electro-Seal at (574) 342-2105
Email us at sales@electroseal.net
Request a Quote
Serving OEMs across aerospace, agriculture, energy, and more.
