A butterfly valve is a device used to isolate or regulate the flow of water. They are used with liquids, gasses, and even semi-solids. While there are various uses for butterfly valves for our purposes we’re going to focus on butterfly valves for fire protection.
In this article, we’ll discover how the butterfly valve works, what components make up the butterfly valve for fire protection, and the different types of butterfly valves. If you’d prefer to float around, refer to the subheadings below or see the butterfly valve category page here.
How does a butterfly valve work?
A butterfly valve for fire protection focuses on the flow of water and functions through the rotation of an internal disc. If the valve is closed, no water can pass through, and when it is open, water can flow through freely. When open, the disc is parallel to the flow and when it’s closed it perpendicular, which closes off the flow of water. The disc remains in the passageway at all times, but because of its thin design it does not create significant resistance.
Running through the center of the disc is a rod connected to a handle. The disc rotates by turning a handle. The rod within the disc connects to an external indicator which turns in sync with the disc and serves to confirm its position – open or closed.
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 a valve's status changes. It is common for a butterfly valve to include two tamper switches. First, for connection to a fire control panel, and second, 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?
As previously highlighted, butterfly valves are relatively simple and consist of only four main components – body, disc, stem, and seat. Their simplistic design makes them a more cost-effective option 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 professionals have completely switched to using a butterfly valve as the control valve.
The components to consider when selecting a butterfly valve depends on design and fabrication needed, which we’ll cover more below. Although there are different seat types, in fire protection they are almost exclusively EPDM-rubber lined. This has become the industry standard due to the products' longevity, especially given infrequent use compared to other industries.
Two final key components of butterfly valves for fire protection is the tamper switch and external indicator. The tamper switch electronically monitors the open or closed status of the valve. When it changes, an alert can be sent to the building’s control panel. The external indicator provides visual affirmation as to the position of the internal disc and whether the flow of water is open or closed.
What is a wafer butterfly valve?
The wafer butterfly valve is designed to be sandwiched between two pipe flanges and uses both nuts and bolts during installation. (Think of wafer sugar cookies, which have icing sandwiched between the two cookies.) Although they are less expensive than lug type butterfly valves, to install or replace a wafer type butterfly valve or either length of pipe the whole system must be shut down.
Lug type butterfly valves differ from the wafer in that they have threaded inserts or “lugs,” which enable installation by bolts alone. Because lug types are attached to each pipe end separately, either section of pipe may be replaced or removed without shutting the system down. Lug type butterfly valves are, for the most part, obsolete in fire protection. They’ve been replaced by the grooved butterfly valve.
What is a grooved butterfly valve?
A grooved butterfly valve is the most common type in fire protection. A grooved butterfly valve features grooved pipe connections that settle nicely with grooved couplings. This installation methond delivers a tight, leak-free seal, and considerably faster installation. They are available for 2.5-inch pipe and larger.
What is a threaded butterfly valve?
A threaded butterfly valve is made of the same internal components, 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 to 1.5” are 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 economic design, butterfly valves have fewer parts, which makes them easier to repair and maintain. Furthermore, their uncomplicated designs alleviate the burdens associated with installation. In turn, this allows cheaper installation costs.
Butterfly valves are versatile because they range in size, pressure capabilities, and temperature ratings. When used for fire protection, butterfly valves range from 1 – 12 in. In the fire protection industry, 175 psi is considered high pressure but many butterfly valves are rated up to 300 psi.
Do butterfly valves require periodic maintenance?
To comply with National Fire Protection Association (NFPA) regulations, 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 butterfly valves must be tested annually.
What to look for:
• The valve is open or closed, whichever is the normal position
• It is sealed, locked, or supervised
• There is no sign of leaks
• Appropriately identified
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”. UL and FM approved butterfly valves with dual tamper switches, external indicators, and EPDM-lined disc, all available online and ready for your next job.
All available online 24/7 - order today and you'll receive a great valve delivered fast.
QRFS delivers butterfly valves fast to your job site anywhere in the country (and world). QRFS offers special pricing for contractors and will respond to requests for quotes on the same day.
Still have questions? Leave them in the comments section below or contact us and we’ll do our best to answer them quickly. Otherwise, jump directly to our selection of butterfly valves by clicking the link below.