#65 - Guide to Butterfly Valves for Fire Protection
#65 - Guide to Butterfly Valves for Fire Protection
Butterfly valves provide lightweight and low-cost control over water flow in fire sprinkler and standpipe systems
A butterfly valve isolates or regulates the flow of fluid through piping systems. While they can be used with liquids, gases, and even semi-solids, butterfly valves for fire protection serve as control valves that turn on or shut off the flow of water to the pipes serving fire sprinkler or standpipe systems.
In this article, QRFS explains how they work, what components make up a butterfly valve, and the different types that are available.
If you'd like, you can click here to browse our selection of butterfly valves for fire protection.
How does a butterfly valve work?
A butterfly valve for fire protection starts, stops, or throttles the flow of water through the rotation of an internal disc. When the disc is turned parallel to the flow, water can pass through freely. Rotate the disc 90 degrees, and the movement of water into system piping stops. This thin disc can stay in the water's path at all times without significantly slowing the movement of water through the valve.
The disc's rotation is controlled by a handwheel. The handwheel rotates a rod or stem, which turns the disc and simultaneously rotates a position indicator – usually a brightly-colored piece sticking out of the valve – that shows the operator which way the disc is facing. This indicator allows for at-a-glance confirmation of whether the valve is opened or closed.
The position indicator plays an important role in keeping fire protection systems operational. Butterfly valves serve as control valves capable of shutting off the flow of water to whole sections of fire sprinkler or standpipe systems. Entire buildings can be left defenseless when a control valve is unintentionally left closed. The position indicator helps fire professionals and facility managers locate a closed valve and re-open it quickly.
The position indicator moves in sync with the disc to identify the valve's "Open" or "Closed" position
Most butterfly valves for fire protection also include electronic tamper switches that communicate with a control panel and alarms when the valve's disc rotates. Often, they include two tamper switches: one for connection to a fire control panel and another for connecting to an auxiliary device, such as a bell or horn.
What components should I look for in a butterfly valve for fire protection?
Butterfly valves consist of only four main components:
- A body, which houses the disc, stem, and seat
- A disc controlling flow of fluid through the valve
- A stem used to rotate the disc and position indicator
- A seat, which forms a water-tight seal with the disc when the valve closes
Their simple design makes them a cost-effective choice compared to other control valves. Because they are lighter, more compact, and easier to install than their predecessor, the OS&Y gate valve (“outside stem and yoke” or “outside screw and yoke”), most fire installers now favor using a butterfly valve as the control valve.
The components to consider when selecting a butterfly valve depends on the needs of the installer and the type of piping used. Although they are made with a variety of valve seats, their seats are almost exclusively EPDM rubber-lined in fire protection. EPDM is favored for its resistance to weather, high and low temperatures, various chemicals, and leakage.
What is a wafer butterfly valve?
The wafer butterfly valve is designed for use with flanged piping systems and held in place using two flanges and a series of nuts and bolts. A wafer valve needs to have the flanges on either side of it connected to each other to hold the valve in place. Consequently, the entire fire sprinkler or standpipe system must be shut down and drained before installing or removing these valves.
What is a grooved butterfly valve?
A grooved butterfly valve is a control valve designed for pipes with grooved ends. The valve connects with simple pipe couplings and gaskets that install considerably faster and form a leak-tight seal. This design makes it easier to replace pipe downstream of the valve. With the valve closed, the coupling downstream from the supply of water can be removed while the upstream coupling remains attached, shutting off the supply of water.
These valves are the modern replacement for lug-type butterfly valves, which use threaded inserts, or “lugs,” that enable installation by bolts alone. Grooved butterfly valves are available for 2 1/2-inch pipe and larger.
What is a threaded butterfly valve?
A threaded butterfly valve is made of the same internal components as wafer or grooved butterfly valves, but both connections are threaded (i.e. it screws onto the pipe). Threaded butterfly valves require precision and accuracy during the installation process because the ends must be threaded on both sides. They are available in multiple sizes, but 1-inch to 1 1/2-inch are the most common.
What are the benefits of a butterfly valve?
In comparison to other valve types, butterfly valves are relatively lightweight, especially at larger sizes. Because they embody a simple and economical design, they have fewer parts, which makes them easier to repair and maintain. Furthermore, their straightforward design reduces the time required to install one, decreasing labor costs.
Butterfly valves range in size, pressure ratings, and temperature ratings. In fire protection, they are available for pipe as small as 1 inch and as large as 12 inches in diameter. Many have pressure ratings as high as 300 PSI.
Do butterfly valves require periodic maintenance?
To comply with standards established by the National Fire Protection Association (NFPA), butterfly valves require weekly inspections. However, if the valve is electrically supervised, it may be inspected quarterly. While there are few specified maintenance requirements, the guidelines do specify they must be tested annually.
When inspecting a butterfly valve, verify that the valve is:
- In the normal position (open during normal system operation or closed during testing or maintenance)
- Sealed, locked, or supervised
- Free of leaks
- Appropriately identified with signage indicating the valve's function and the part or parts of the system it serves
Why choose QRFS for your butterfly valve needs?
QRFS offers all three types of butterfly valves – wafer, grooved, and threaded – in sizes ranging from 1” to 8”. These valves are UL-listed and FM-approved and are available with dual tamper switches, external indicators, and an EPDM-lined disc.
QRFS delivers parts to your job site fast, anywhere in the country (and world). We also offer special pricing to contractors and respond to requests for quotes on the same day.
This blog was originally posted by Jason Hugo and Anna Hartenbach at QRFS.com/blog on June 2, 2017, and updated on January 1, 2019. If this article helped you select the right check valve, check us out at Facebook.com/QuickResponseFireSupply or on Twitter @QuickResponseFS.