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Butterfly Valves Guide

Butterfly Valves are a kind of valve that regulate or control fluid flow via a rotating disc. They feature quarter-turn capability for full open or full close, simple lever handle or actuated operation and have a relatively large coefficient of volume (meaning low pressure loss at high flowrates). Butterfly valves are especially popular due to their light weights, compact size and comparatively low costs.

by Tom Hansen P.E.by Tom Hansen, P.E. | ©Dultmeier Sales

Wafer Body Butterfly Valves

Wafer butterfly valves (or wafer body butterfly valves) are more economical than their counterpart, lug butterfly valves. Typically manufactured with EPDM & Buna seats, stainless discs and stainless stems, wafer butterfly valves are compact and versatile. The lever handles can normally be used to set the valves in ten different positions ranging from closed to fully open. They can also be controlled with a variety of air and electric actuators. They are designed to prevent backflow in systems made for unidirectional flow. A flat valve face upstream and downstream of the valve, as well as a tight fitting gasket or o-ring helps this process.

Dultmeier Sales stocks wafer body butterfly valves designed to fit between standard 125 lb. / 150 lb. ANSI flanges with "thru" bolts that run along the outside rim of both flanges.

Wafer Style Keystone Butterfly Valve Fig. 221

Keystone Fig. 221

Wafer Butterfly Valves with Lever Handles, 2" - 10"

The Keystone 221 series valves (KE906-XX) feature rugged construction and lockable handles, as well as a maximum flow area for use in on/off and throttling applications. The standard seat is FDA rated EPDM or Buna, and are designed to completely isolate the valve body parts from the liquid. Rounded, hand polished disc and hub edge give full concentric seating, providing maximum seat life.

Wafer Style Pratt Butterfly Valve, OS Series

Pratt OS Series

Wafer Body Butterfly Valves with Lever Handles, 2" - 8"

Pratt's Heavy Duty OS Series Wafer Butterfly valves (PTOSX) are constructed with lockable handles, EPDM/Buna seats and a max flow area for throttling and on/off applications. The top flange conforms to ISO5211 industrial standard, while the blowout proof stem meets API609. Two internally driven shafts create a strong drive connection and thin profile disc, allowing for high flow rates.

Wafer Style Pratt Butterfly Valve, OS Series

Pratt OS Series, Bare

Wafer Body Butterfly Valves without Lever Handles, 2" - 8"

Similar to Pratt's OS Series, these valves ship with a bare stem and no handle, making them ideal for replacement parts or other applications. See our product page for additional information, including material, flow rates at different sizes, and related products.

Lug Body Butterfly Valves

Lug butterfly valves, while slightly less economical than wafer valves, offer many of the same features. Installed between two flanges with a separate set of bolts for both, lug valves allow piping to be disconnected on either side of the valve without disturbing the other side.

Dultmeier Sales does stock lug body butterfly valves which also have the advantage of being used in "end of line" (dead end) applications with a flange on just one side of the valve, but typically feature a reduced pressure rating when used as such.

Lug Style Keystone Butterfly Valve GRL Series

Keystone GRL Series

Lug Style Butterfly Valves with Lever Handles, 2" - 10"

The rugged construction of the Keystone GRL Series butterfly valves (KEGRL-XX) is ideal for most applications involving water, air and dry bulk conveying, or any service where a drop-tight shutoff with max flow area is required. Standard with 805 trim, 316SS disc and stem, and replaceable EPDM/Buna seats. Lug type bodies are drilled and tapped, allowing for isolation and removal of downstream piping.

Lug Style Keystone Butterfly Valve Series 920

Keystone 920 Series

Lug Style Butterfly Valves, Split Body, 2" - 8"

Keystone's 920 Series lug type valves are a perfect fit for automotive applications, beverages, biofuels, blowers and much more. With a thin disc, resilient seat and split body, the 920 allows for easy field replacement of seat and disc/stem. A one-piece disc and stem results in maximum flow rates, low pressure drops and excellent control capabilities.

Lug Style Keystone Butterfly Valve Fig. 222

Keystone 222 Series

Lug Style Butterfly Valves with Lever Handles, 2" - 6"

Similar to the Keystone 221 Series Wafer Valves, the 222 Series (KE222-XLUG) are lug type valves and are drilled and tapped. This allows for isolation and removal of downstream piping at full rated pressure. EPDM seats are standard, Viton and Buna available. Visit our product page for more information and related items.

Keystone Spring Return Air Actuated Butterfly Valve

Keystone Air Actuated GRL Series, Single Acting

Lug Type Butterfly Valves, Air Actuated with Spring Return, 2" - 12"

Keystone GRL Series valves with spring return air actuation (DUGRL-XXXKSR) are cast iron with EPDM Seats and stainless steel discs and stems. The valve is identical to the GRL series mentioned above. Single Action valves, or spring return valves, are driven by the air output of the control valve positioner on one side, while the other is moved by a spring.

Keystone Double Acting Air Actuated Butterfly Valve

Keystone Air Actuated GRL Series, Double Acting

Lug Type Butterfly Valves, Air Actuated Double Acting, 2" - 12"

Similar to the valves above, the GRL series valves with double action air actuation (DUGRL-XXXK) feature rugged construction with cast iron bodies, EPDM seats and stainless discs and stems. Double Acting air actuation works by way of a control valve driven by the output air from a control valve positioner on both sides of the valve.

Keystone Series 221 Air Actuated Butterfly Valves

Keystone Series 221 Valves With Single Acting Air Actuator

Wafer Style Butterfly Valves with Keystone Air Actuator, Spring Return, 2" - 6"

The Keystone 221 Series valve with a Keystone air actuator on top. Spring Return actuators feature a simple design ideal for safety and reliability. The 221 valves include cast iron bodies, EPDM seats and stainless discs and stems. Air actuators are direct mount (no brackets) and include 1/4" FPT air port connections. Not suitable for Diesel fuel.

Keystone Series 221 Air Actuated Butterfly Valves

Keystone Series 221 Valves With Double Acting Air Actuator

Wafer Style Butterfly Valves with Keystone Air Actuator, Double Acting, 2" - 6"

This Keystone 221 Series Wafer Style Butterfly valve includes a direct mounted double acting air actuator. The valve includes a cast iron body, EPDM seat, stainless discs and stems, and is rated to 250 PSI and 250 Deg. F. Double Acting air actuators are ideal for placement in last position, where it's pressurization on both sides ensures that the valve is held safely and securely in case of signal or supply loss.

Keystone Series 990 Split Body Wafer Style Valves

Keystone 990 Series Split Body Butterfly Valves

Split Body Wafer Style Butterfly Valve, 2" - 8"

Keystone's 990 Series split body wafer style butterfly valves feature a thin disc, resilient seat, and a split body design for easy field replacement of seat and disc/stem. One-piece thin profile disc/stem results in maximum flow rates and low pressure drops. EPDM seats are standard, Buna and PTFE lined also available. Suitable for installation between ANSI Class 125/150 flanges.

Keystone Pneumatic Actuators

Keystone Pneumatic Actuators

Spring Return and Double Acting Pneumatic Actuators, 2" - 8"

Mounted directly to Keystone butterfly valves to provide remote operation, no brackets required. Spring Return models close automatically when air is shut off. Double Acting models require two air lines, one to close and one to open the valve. 1/4" FPT air connections. Supply pressure is rated at 120 PSI, with a 150 PSI max.

Keystone Electric Actuators

Keystone Electric Actuators

Electric Actuator, 2" - 6"

Keystone has an extensive range of electric valve actuators. Models are outdoor rated (Nema 4/4X/6) and run on 120V or 240 VAC single phase and are standard on/off only (1/4 turn). Manual override hand wheel. Manual override hand wheel included.

Dultmeier Sales stocks Wafer, Lug Style and Actuated Butterfly Valves from Keystone & Pratt.

Stock butterfly valve bodies are standard in cast iron (since bodies are a non-wetted component) with EPDM seats and stainless discs & stems. EPDM seated butterfly valves are compatible with water, fertilizer and some diluted chemicals but should not be used with fuels, oils or other hydrocarbons. Buna seated butterfly valves are compatible with standard diesel fuel, many oils, water & most fertilizers. Viton® seats & teflon coated EPDM or Teflon coated Buna seats are also available.

Always confirm seat material, disc & stem compatibility with all products you will be running through the butterfly valves.

Tom Hansen, P.E.  |  Dultmeier Sales
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