What are two advantages of using a spectacle blind compared to a line blind?

Using a spectacle blind offers distinct advantages when it comes to operating piping systems, especially in terms of visual indication. The key benefit of being able to determine at a glance whether a line is open or closed is significant for safety and operational efficiency. A spectacle blind features a circular opening (the "spectacle" part) that indicates an open line when aligned in line with the pipe, and a solid section (the "blind" part) that blocks the flow when positioned accordingly. This visibility allows operators to make swift, informed decisions without the need for additional checks or instruments, greatly enhancing response times during maintenance or emergency situations.

While the other options touch on attributes of pipe fittings, they don't align as closely with the specific functional advantages of a spectacle blind. Stronger construction and lower cost pertain to the general characteristics of different types of blinds but do not specifically highlight the unique benefits of the spectacle design. Lightweight and flexible, while beneficial traits in some contexts, are not typical features associated with spectacle blinds. Similarly, while some spectacle blinds can withstand high temperatures and pressures, this is more a characteristic of the materials used rather than a defining advantage of the design itself compared to line blinds.