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Spectacle Blind or Line Blind: How to Choose the Right Positive Isolation Device?

The Importance of Spectacle Blind in Positive Isolation

A traditional spectacle blind flange in 3D render.

A spectacle blind, often referred to as an ‘8 blind’, is an important piping fitting designed for providing positive isolation. Including a pair of metal discs conjoined, as described in many industry diagrams. In fact, they’ve earned the name ‘line blanks’ due to their primary function of blanking a line. The spectacle blind stands out as a preferred choice in the piping industry for positive isolation. The reason? It’s perfectly aligned with the all requirements laid out in the ASME B16.48 and OSHA 1926.1202 / 1910.146 standards. As we delve deeper, it’s crucial to understand how line blind compare to the spectacle blind.

Mechanical Line Blind: How Does It Differ from Spectacle Blind?

Mechanical line blinds are permanently installed on pipes, functioning similarly to valves but specifically designed for positive isolation. Unlike traditional methods, mechanical line blinds mechanize pipe spreading and clamping movements, enabling positive isolation without the need for fasteners or additional pipe fittings. While their initial investment might be higher, their long-term profitability and efficiency make them a worthy consideration.

ONIS Device vs. Spectacle Blind: A Detailed Comparative Analysis

The ONIS Quick Action Line Blind (QLB) represents the best of mechanical line blinds. Designed for efficiency and safety, the ONIS QLB facilitates positive isolation in few minutes, requiring just a single operator without any tools. This not only eliminates time-consuming, labor-intensive, and potentially hazardous traditional methods like 8 blind but also significantly reduces fugitive emissions.

The ONIS QLB acts as an extra layer of safety, minimizing operator exposure and potential human errors during operations. Unlike spectacle blinds, which require operator judgment, all ONIS blinds are pre-set at the factory, ensuring reliable performance. Specifically crafted for critical applications, congested areas, and handling hazardous products, the ONIS QLB is the go-to choice for operations with more than two pipe blanking activities annually.

On the other hand, spectacle blinds, while being more cost-effective upfront, can demand several hours for installation and need at least three operators equipped with heavy-duty tools. They are best suited for less congested areas and operations with fewer than two pipe blanking activities a year.

Finally, both ONIS QLB and spectacle blinds comply with the ASME B16.48 and OSHA 1926.1202 / 1910.146 standards.

Comparison of a blanking operation with a spectacle blind and with an Onis line blind.

Making the Right Choice

In conclusion, the choice between spectacle blinds and mechanical line blinds like the ONIS QLB boils down to specific operational needs and frequency of use. While spectacle blinds are affordable and reliable, the ONIS QLB offers more. Indeed, it provides efficiency, safety, and is long-term profitable for regular operations. By understanding each device’s unique features, industries can decide wisely. Our experts can help you make the right choice for your process.

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What is positive isolation ?

What is positive isolation ?

In pipe industry, there are different methods of isolation including positive isolation. Focus on the best solution: the pipe blinding operation.

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