SECTION 21 0523 – GENERAL-DUTY VALVES FOR WATER-BASED FIRE-SUPPRESSION PIPING
- General Description
- Ball Valves with Indicators
- Butterfly Valves
- Check Valves
- Gate Valves
- Indicator Posts
- Globe Valves
- Trim and Drain Valves
- Valve Actuators
- Supervisory Switches
- Product Selection and Application Considerations
This section includes valves most commonly used in fire suppression piping systems. Fire Suppression System valves are required to be UL-Listed or FM Global approved. Valves rated solely for fire suppression are not suitable for potable water applications. Conversely, valves used for potable water may not be rated or suitable for use in fire suppression systems.
Valves are generally specified by valve type and not the service the valve provides. Many different valve types provide the same services such as shutoff and balancing. Design Professionals need to determine which type of valve is suitable for each particular service application.
Valves are often categorized by the material that comprises the valve body. Valve categories are not limited to this categorization but it has been adopted, where applicable in our sections to coincide with categorization by valve manufacturers.
Traveling-nut or Worm-gear Actuators and Indicators are required for ball and butterfly valves that are Underwriters Laboratories (UL) listed and FM Global approved with the exception of trim and drain valves. Actuators prevent resultant water-hammer effects caused by operating valves too quickly. Indicators show what position valves are, i.e. open or closed.
Handlevers attached to the valve stem are most common for trim and drain applications.
One-piece ball valves have a valve body cast/forged as one piece. The ball is inserted through the end of the body and held in position by an insert. These valves are regular port only.
Two-piece ball valves, have a valve body constructed in two pieces. The ball is held in position by a stud. These valves are full or regular port.
Three-piece ball valves have two end pieces and one center piece held by studs. This construction permits valve maintenance without disturbing existing pipe work.
Ball valves, suitable for shutoff and moderate throttling, are butterfly valves with holes, or ports, through the middle of their spherical discs. When ports align with valve ends, valves are open and flow occurs. When ports are perpendicular to valve ends, valves are closed and flow stops. Handles on ball valves are aligned with the ports so you can tell if the valve is open or closed. Ball valves lack precise control usually necessary for precision throttling.
Valves of cast bronze are less subject to dezincification than valves of forged brass, but may be subject to casting defects such as blow holes.
Balls in ball valves are chrome-plated brass or stainless steel, have solid or hollow patterns, and a port.
Port sizes may vary with manufacturer. As defined in MSS SP-110,
- Full port means equal to the nominal valve size.
- Regular port (aka. conventional or standard port) means equal to 75% of the nominal valve size.
- Reduced port means equal to 62% of the nominal valve size.
Most ball valves are designed to vent fluid around the ball to prevent stem leakage and seat failure during expansion due to pressure or temperature cycling. These should be used where fluids are subject to pressure or temperature change issues.
Ball valves available in NPS 1/4 to NPS 4 (DN 8 to DN 100) are bronze, brass, copper-alloy threaded, and solder-joint types. Due to high-operating torque of larger sizes, most of these valves are limited to NPS 2 (DN 50). Grooved-end ball valves are usually used for sizes NPS 1-1/4 and NPS 2-1/2 (DN 32 and DN 65).
Butterfly valves, used to control and regulate flow are composed of a discs mounted on rods in the center of the flow passageway. An actuation device exterior to the valve body is attached to the stem. When the disk blocks the passageway, the valve is closed and flow stops. The valve can be opened incrementally to throttle and regulate flow. Single-flange and grooved-end valves are specified for Fire Suppression in SpecLink.
Butterfly-valve bodies are cast or ductile iron. Bronze is common for smaller sizes up to NPS 2-1/2 (DN 65). The valves ave liners that are in contact with the fluid and shield the valve body.
Liner Materials suitable for Fire Suppression Applications:
- Ethylene-propylene-diene terpolymer rubber: Most Common and rated to 250 deg F (121 deg C) maximum temperature.
- Buna N or NBR (Acrylonitrile-butadiene rubber): Oil resistant and rated to 180 deg F (82 deg C) maximum temperature.
For fire-suppression purposes, the discs in butterfly valves UL listed and FM Global approved must have corrosion-resistant properties equivalent to or greater than cast iron. Common disc materials are bronze, nickel plated ductile iron, monel (nickel alloy), and stainless steel. Disc coatings must be mechanically secured, bonded, or vulcanized to the metallic disc. Uncoated discs of ductile iron will rust and may cause damage to the liner.
Butterfly valves for installation between Class 125 or Class 150 flanges are available in NPS 1-1/2 to NPS 72 (DN 40 to DN 1800).
Valves NPS 2 to NPS 12 (DN 50 to DN 300) are usually rated for 200-psig (1380-kPa) CWP (cold working pressure). Valves NPS 14 (DN 350) and larger are usually rates for 150-psig (1035-kPa) CWP The "bubble-tight shutoff" rating, which ensures that the valve does not leak, is important criteria but should also be supplemented with the criteria by which the rating was derived.
Check valves allow flow to be in only one direction. This is accomplished by means of a hinged mechanism, called a clapper, and is available in several configurations. The only types used in fire-protection piping systems that are both UL listed and FM Global approved are single swing check valves that only have one clapper. Twin swing check valves have two clappers and are bot suitable for fire suppression. Other types of check valves are wafer, lift, and spring loaded,
Single swing check valves, must be located so the clapper closes freely and positively by gravity unless spring loaded. For check valves with removable covers, clearance must be provided to permit clapper removal.
Valves NPS 2 to NPS 12 (DN 50 to DN 300) are most common.
Some typical check valve locations in fire suppression systems are between public water supplies and private fire-service systems, fire pump discharge, gravity tank connections, and fire-service pumper connections.
Gate valves are designed for shutoff applications. The valves have flat gates or wedges that are removed from the flow path in the valve. They are not suitable for regulating or throttling flow. Typically solid wedges are used in fire-protection applications, though various wedge types are available. Flow is blocked, when the wedge is secured against a metal or elastomeric seat. Some amount of leakage is allowed,but often the wedge or the wedge seat is encapsulated in an elastomeric material to facilitate no leakage at all.
Valve Stem Types:
- Rising-Stems indicate the wedge position and require extra space to open because of the stem. These valves are used aboveground or in outdoor pits.
- Outside Screw and Yoke (OS&Y) stems are rising-stems with an adjustment screw nut that is supported by an A-frame yoke outside the valve body. The nut is held in a fixed position and turned by an attached handwheel, or gear actuator. The stem rises or lowers into the valve body and pulls or pushes the wedge to open or close the valve. The position of the stem for an OS&Y gate valve tells if it is open or closed.
- Nonrising-Stems (NRS) are recommended for cramped spaces. The shaft screw nut is built into the wedge. The wedge rides up and down the internal shaft threads when the handle and shaft turns either opening or closing the valve. These valves are used below-ground.
- Rising-stem and OS&Y gate valves are actuated by using a handwheel or wrench applied to a wrench nut attached to the valve stem. Rising-stem and OS&Y gate valves do not require indicators because the gate position is evident by the stem location.
- NRS gate valves are available with or without a base flange for attaching an indicator post. Valves without base flanges are actuated with a wrench, wall indicator post, or tee-handle wrench for buried applications.
Gate valves are commonly available in NPS 1/2 to NPS 12 (DN 16 to DN 300) for fire-suppression applications.
Indicator posts open and close valves located in difficult to reach locations, i.e. underground or behind a wall. Though commonly used with NRS gate valves they are used with other valves as well. They are primarily intended for use controlling water supplies to fire-suppression systems where connections enter the building envelope.
Indicator posts have a flange barrel and attach to the valve itself. This barrel often has an upper telescoping flanged extension that allows for height adjustment of the indicator post. A stem runs the length of the barrel which attaches to the stem of the NRS valve. The stem turns by using an operating wrench or a handwheel actuating the valve. A telescoping union is used allow the indicator stem to remain at a constant height. An indicator show whether the valve is open or shut. You can lock posts in the open or closed position, depending on the application. Operating wrenches or handwheels attached to the posts are made to be "locked" in place which locks the valve in the position desired. Wall-indicator posts mount on a wall and have a rod coupling extension that goes between the wall-indicator stem and the valve.
Globe valves or ‘stop valves’ throttle and balance flow in addition to shutoff. The valves are halved by an internal baffle. The baffle forms the and a movable disc is screwed into it to throttle or shut off flow. The disc, via the valve stem that can be turned by various methods to adjust the valve. Many globe valves today do not have a spherical shape. The housing has inline inlet and outlet ports for fluid to flow in and out. Three port valves are not uncommon. Pressure drops in globe valves are high because the fluid must change direction twice inside the valve in order to pass through the baffle and around the disc before reaching the outlet port.
Globe valves have rising stems which indicate the position of the disc. This requires extra space to operate the valve. Globe and angle valves for trim and drain applications are actuated by using a handwheel or handlever or a wrench applied to a wrench nut attached to the valve stem.
Angle valves are globe valves where the ports are arranged so the outlet is perpendicular to the inlet. Because flow changes direction only once in the valve before reaching the outlet there is less flow resistance than regular globe valves.
Globe valves are available in NPS 1/8 to NPS 12 (DN 6 to DN 300), but the smaller sizes are most frequently used.
The most common trim and drain valves are ball type. These ball valves are UL listed. There are also angle and globe types available but no UL standard exists for these valves. The requirements governing these valves are in UL Subject 258, Outline of Investigation for Shutoff Valves for Trim and Drain Purposes. There is no specific FM Global category where trim and drain valves are located.
Trim and drain valves are NPS 2 (DN 50) and smaller.
Actuators supply forces needed for valve operation. System controls operated motorized actuators. There are five basic types of manual actuators.
Worm-gear actuators produce high thrust. They mount on valve stems for opening or closing valves. They may be motorized, handlever, or handwheel operated. For fire suppression they are used on all indicator ball and butterfly valves. These actuators operate with very low torque compared to other actuators, and open valves slowly, reducing water hammer effect in the piping.
Linear actuators are handlever or handwheel operated from one end of a lead screw (can also be attached to a gearbox). When the lead screw is turned, a nut, retrained from turning. travels up and down the lead screw. Linkage attached to the nut actuates the valve. These actuators require lower torque than other actuators, and open valves slowly, reducing water hammer effect in the piping.
Handlevers open, close, and may lock in position on quarter-turn valves. They attach to the valve stem and are suitable for trim and drain applications.
Handwheels are used to open or close multi-turn valves.
Wrenches are levers not permanently attached to valves, used to open or close quarter-turn valves.
Supervisory switches mount to control valves in a fire suppression system. They monitor whether valves are open or closed. Valves can be purchased with supervisory switches mounted to them as an option. Sprinkler systems fail when control valves are unintentionally left closed, rendering the sprinkler system inoperable. Valve that affect water flow in a fire sprinkler system must be monitored and provide signals to a control panel or monitoring device.
MSS SP-92, MSS Valve User Guide, contains information on valve selection and application.
Shutoff Applications: Use valves according to the following:
- Valves no larger than NPS 2 (DN 50): Bronze ball or gate valves or iron plug valves. Gate valves with rising stems tend to last longer than NRS gate valves.
- Valve no smaller than NPS 2-1/2 (DN 65): Iron ball, butterfly, gate, or plug valves. OS&Y gate valves tend to last longer than NRS gate valves.
Throttling Applications: Use valves according to the following:
- Valves no larger than NPS 2 (DN 50): Bronze angle or globe valves. Ball and plug valves for moderate throttling.
- Valve no smaller than NPS 2-1/2 (DN 65): Iron angle, butterfly, or globe valves. Ball and plug valves for moderate throttling.
- Angle valves have less pressure loss than globe valves.
Valve Ends: Use valves with ends according to the following:
- Valves no larger than NPS 2 (DN 50): Threaded ends.
- Valves no smaller than NPS 2-1/2 (DN 65): Flanged or threaded ends.
- Valves no smaller than NPS 5 (DN 125) and Larger: Flanged ends.
- Several valve types and sizes, NPS 2 (DN 50) and larger, are available with grooved ends.
UL Listed: Valves specified and used should be listed in UL's Online Certifications Directory under the headings below. Only products bearing the UL mark are considered to be UL listed.
- Main Level: HAMV - Fire Main Equipment
- Level 1: HCBZ - Indicator Posts, Gate Valve
- Level 1: HLOT - Valves
- Level 3: HLUG - Ball Valves, System Control
- Level 3: HLXS - Butterfly Valves
- Level 3: HMER - Check Valves
- Level 3: HMRZ - Gate Valves
Trim and Drain Equipment:
- Main Level: VDGT - Sprinkler System & Water Spray System Devices
- Level 1: VQGU - Valves, Trim and Drain
FM Global Approved for Fire Protection: Valves specified and used should be listed in FM Global's Approval Guide, under the headings below:
- Automated Sprinkler Systems
- Indicator Posts
- Gate Valves
- Check Valves
- Single Check Valves
- Miscellaneous Valves
- Indicating Valves, Butterfly and Ball Type
Consult authorities having jurisdiction Most will comply with UL and FM Global standards. Authorities vary as to whether products are UL listed or FM Global approved, or both. Insurance companies may require FM Global approval regardless of jurisdiction authorities.