SECTION 21 1100 – FIRE-SUPPRESSION WATER-SERVICE PIPING
- General Description
- Piping Materials
- Private Fire Hydrants
- Water Supply Backflow Assemblies
- Water Meters
- Performance Requirements
- How to Specify
In most jurisdictions, the Sprinkler Contractor only performs work inside the building extending up to 5 ft (1.5 m) from the building foundation. The Site Contractor usually performs the incoming fire line work exterior to the building. There are certain jurisdictions where the Sprinkler Contractor is required to perform the exterior, incoming fire line work that is solely dedicated to the building sprinkler system. This Section is to be used for those situations.
This section includes piping materials for the fire suppression water service from the utility water service line to the building structure including fire hydrants closely associated with the building structure, piping encasements, valves, alarms, water meters and boxes, concrete vaults, enclosures, fire department connections, and water supply backflow assemblies.
Fire Department Connections:
One of the least understood components of a reliable and adequate water supply is the fire department connection (FDC) which is sometimes referred to incorrectly as a sprinkler connection, standpipe connection, or “Siamese”. With few exceptions, FDCs are required on almost all sprinkler systems complying with NFPA 13 and NFPA 13R. The exceptions consist of buildings that are too remote where fire department intervention is unlikely and are too small as to not receive any benefit. The FDC is intended to provide sprinkler systems with a means to receive supplemental water support from a fire department pumping apparatus. Events such as tornados, hurricanes, earthquakes, floods, and comparable events can interrupt water flow provided from the water utility line due to failure of pumping stations or damage to the water supply infrastructure piping leaving the FDC as the last possible resort of providing water to the building sprinkler system. Water supplies are generally provided by shuttles, tankers, and drafting during such catastrophic events before restoration of the water utility system.
Notwithstanding the importance of providing a reliable and adequate supply of water is the requirement for immediate operation when the fire fighting vehicles arrive at an FDC equipped structure. It should be noted that Annex language to Section 6.8.1 in NFPA 13 reinforces the supplemental nature of FDCs , and that they do not necessarily supply the system demand, but rather provide a desirable, auxiliary supply which increases the overall reliability of the fire-suppression system. The location of the FDC is primarily driven by the applicable codes for the jurisdiction to ensure full visibility, immediate and full access to the FDC from the point of fire department vehicle access including the ladder company, unobstructed by landscaping, fences, trees, including the engines, and hose lines. NFPA 13R and NFPA 5000 do not contain regulations or limitations for FDC location or accessibility, therefore it may be prudent to provide language to enforce “immediately accessible” provisions in Part 3 of Section 211100 (13908).
Minimum signage is required which is typically spelled out in the code applicable to the jurisdiction. These codes dictate the height of raised letters, which requires specific verbiage such as “test connection”, “automatic sprinklers”, “standpipes”, or a combination thereof, depending on the actual building conditions. Major fire equipment manufacturer’s stock pipe escutcheon rings that are properly fabricated of metal with raised lettering that meet exact requirements of the applicable code including several other options plus contrasting red and white colors to cover most common system installations. There is also language available to provide supplemental signage when a FDC connected system does not serve an entire building. History has shown this is routinely overlooked and can lead to critical decision errors or the fire ground, particularly when only certain areas of the building or occupancies require protection. Since this type of signage is not specifically regulated by codes, the Building Authority Having Jurisdiction will need to be specific regarding material, size, color, and content editing to avoid confusion.
FDC hose connections must be compatible with those of the local responding fire apparatus. To that end, it is vital that some type of verification i.e. Field Quality Control Submittal, be included in the submittals required for the project. Unfortunately, and all too often, it takes an emergency to finally discover the problem relating to mismatched threads when compared with the local fire department threads. NFPA 13 specifically calls for female swivel fittings on the FDC. The reason this becomes important is that some hose connections resemble an FDC but, in actuality, are not intended for fire department support. In buildings containing a fire pump, there is usually an exterior test header that looks like a FDC, except that it has male-threaded hose connections. This highlights that critical need for correct signage or markings, since it is possible that a fire fighting crew might attempt to connect to a test header with a pair of double-female swivels. Similarly, there are premises equipped with wall hydrants, closely resembling FDCs. Again, this accentuates the need for clear and legible signage.
The standard FDC has historically been considered as being equipped with two 2-1/2 NPS (65 DN) female swivel connections which probably gave way to the “siamese” designation. There are, however, numerous other connection configurations that are commercially available, ranging from single to four-way connections. Depending on site conditions, they are also available as pedestal mounts or for wall mounting. Recent years have seen the introduction of sexless or quick-connect type fittings on system FDCs typically with four or five inch hose. The Building Authority Having Jurisdiction would still make the final selection to insure compatibility with the hose fittings. There are important considerations that need to be addressed when using these fittings and large diameter hose (LDH) connections for existing and new system installations. LDH was originally introduced as a way to provide large water volumes over long distances with reduced friction loss as compared to the traditional 2-1/2 NPS (65 DN) or 3 NPS (80 DN) supply lines. This characteristic of large water volume and reduced friction loss did not contemplate significant pressure loss due to elevation, such as standpipes in high-rise buildings. LDH delivers water volume to the pumper apparatus which produces the required operating pressure for fire-fighting operations, including standpipes for hose stream reach/penetration and fire sprinkler coverage. Successful usage of LDH to move large water volumes is also dependent on the pumping apparatus’ design and piping. The installation of an adapter to convert an existing 2-1/2 NPS (65 DN) discharge into a 5 NPS (125 DN) discharge creates a chokepoint at the pump discharge resulting in increased water velocity and additional friction loss due to flow increase.
The hose also needs to be taken into account. Since LDH is generally classified as supply hose, its service pressure is 200 psi (1380 kPa), whereas 3 NSP (80 DN) hose is available with service pressure listings from 300 psi (2070 kPa) to 600 psi (4140 kPa). Minimum pressures considerably above 200 psi (1380 kPa) need to be considered when properly supplying standpipe systems, particularly in multi-zone buildings. Although the friction loss in 100 ft (30 m) of hose between the pumper apparatus and the FDC will be less in the LDH, pumping 175 psi (1205 kPa) through the LDH and supplying 1000 gpm (3785 lpm) would be inadequate for fire departments operating off the standpipe system if the requirements to reach the fire-fighting crews and support their hose streams are250 psi (1725 kPa) and 750 gpm (2840 lpm). The use of three or more 3 NPS (80 DN) hose lines into the FDC can easily deliver more than 750 gpm (2840 lpm) and more importantly, with the required pressure to overcome the elevation loss in reaching them. Large-demand sprinkler systems or standpipes requiring flow of more than 750 gpm (2840 lpm) are still better served by multiple (three or more) hose lines through a 3-way or 4-way FDC.
NFPA 24 (2015 Edition) – INSTALLATION OF PRIVATE FIRE SERVICE MAINS AND THEIR APPURTENANCES requires that the following piping materials, suitable for underground installation, be listed for fire protection service or comply with the following standards:
- Ductile Iron:
- AWWA C104 Cement-Mortar Lining for Ductile-Iron Pipe and Fittings
- AWWA C105 Polyethylene Encasement for Ductile-Iron Pipe Systems
- AWWA C110 Ductile-Iron and Gray-Iron Fittings
- AWWA C111 Rubber-Gasket Joints for Ductile-Iron Pressure Pipe and Fittings
- AWWA C115 Flanged Ductile-Iron Pipe with Ductile-Iron or Gray-Iron Threaded Flanges
- AWWA C116 Protective Fusion-Bonded Epoxy Coatings for the Interior and Exterior Surfaces of Ductile-Iron and Gray-Iron Fittings for Water Supply Service
- AWWA C150 Thickness Design of Ductile-Iron Pipe
- AWWA C151 Ductile Iron Pipe, Centrifugally Cast
- AWWA C153 Ductile-Iron Compact Fittings
- AWWA C600 Standard for the Installation of Ductile Iron Water Mains and Their Appurtenances
- AWWA C200 Steel Water Pipe 6 In. (150 mm) and Larger
- AWWA C203 Coal-Tar Protective Coatings and Linings for Steel Water Pipelines Enamel and Tape (Hot Applied)
- AWWA C205 Cement-Mortar Protective Lining and Coating for Steel Water Pipe 4 In. (100 mm) and Larger – Shop Applied
- AWWA C206 Field Welding of Steel Water Pipe
- AWWA C207 Steel Pipe Flanges for Waterworks Service – Sizes 4 In. Through 144 In. (100 mm Through 3,600 mm)
- AWWA C208 Dimensions for Fabricated Steel Water Pipe Fittings
- AWWA M11 Steel Pipe – A Guide for Design and Installation
- AWWA C300 Reinforced Concrete Pressure Pipe, Steel - Cylinder Type
- AWWA C301 Prestressed Concrete Pressure Pipe, Steel - Cylinder Type
- AWWA C302 Reinforced Concrete Pressure Pipe, Noncylinder Type
- AWWA C303 Reinforced Concrete Pressure Pipe, Bar-Wrapped, Steel-Cylinder Type
- AWWA C602 Cement-Mortar Lining of Water Pipelines in Place – 4 In. (100 mm) and Larger
- AWWA C900 Polyvinyl Chloride (PVC) Pressure Pipe and Fabricated Fittings, 4 In. Through 12 In. (100 mm Through 300 mm), for Water Transmission and Distribution
- AWWA C905 Polyvinyl Chloride (PVC) Pressure Pipe and Fabricated Fittings, 14 In. Through 48 In. (350 mm Through 1,200 mm), for Water Transmission and Distribution
- AWWA C906 Polyethylene (PE) Pressure Pipe and Fittings, 4 In. (100 mm) Through 63 In. (1,600 mm) for Water Distribution and Transmission
- ASTM B75/B75M Standard Specification for Seamless Copper Tube
- ASTM B88 Standard Specification for Seamless Copper Water Tube
- ASTM B251 Standard Specification for General Requirements for Wrought Seamless Copper and Copper-Alloy Tube
Note that it is acceptable to use underground pipe that is not referenced above but is specifically listed for Fire Protection Service and complies with the applicable AWWA or ASTM standards for the pipe.
The application of polyethylene tube or sheet encasement has proven to be economical, highly effective protection, in areas where severely aggressive soils are encountered or where required by the Building Authority Having Jurisdiction. The protection against corrosion by utilizing loose polyethylene should not be confused with coatings applied directly to the pipe barrel. The most significant difference is the ability to protect without the creation of concentration cells (internal pipe mounds resulting from a failure of cathodic protection) at holidays (pinholes and voids in thin-film coatings). Damage resulting from shipping, handling, etc. is minimized because the encasement is applied at the time when the pipe is put into the ground. Polyethylene wrap in tube or sheet form for piping encasement is manufactured from virgin polyethylene material conforming to the requirements of ASTM D1248. The specified minimum thickness for linear, low-density polyethylene film is 0.008 inches (8 mils). The specified minimum thickness for high-density, cross-laminated polyethylene film is 0.004 inches (4 mils).
Since water may exist in the soil surrounding the piping, water may also exist between the wrap and pipe. Corrosion may begin due to the fact that water between the polyethylene and piping can mirror some of the characteristics attributable to the soil environment. Within a short time frame, however, the initial oxidation along with other electrochemical reactions will deplete the oxygen present in the water, thereby reaching a state of equilibrium and arresting the corrosion.
The first field installation of polyethylene wrap on gray iron pipe, initially developed in the United States, occurred in 1958 which was followed by installations in severely corrosive soils throughout the USA. Due to the success of this encasement procedure, this approach was adopted by several other countries resulting in the creation of ISO 8180: Ductile Iron Pipes – Polyethylene Sleeving for Site Application.
Research by the Ductile Iron Pipe Research Association (DIPRA) at several, severely corrosive test sites has verified that polyethylene encasement provides a high degree of protection resulting in minimal and insignificant exterior surface corrosion of encased gray or ductile iron pipe. These findings have subsequently been confirmed by the results of hundreds of investigations of field installations. Field tests have also indicated that the dielectric capability of polyethylene provides shielding for ductile iron pipe against stray current at most levels encountered in the field. For protection in areas of severely aggressive soils, AWWA C105 covers materials and installation procedures for polyethylene encasement of underground installations of ductile iron piping for water and other liquids. As of this writing, additional information is available at http://www.dipra.org.
When compared to cathodic protection systems, polyethylene encasement provides passive and less expensive protection without continued monitoring, maintenance, and other operating expenses such as trained personnel. This is not to say that the application of cathodic protection should not be used. Cathodic protection may very well be more applicable in highly aggressive soils. Since the protection of below grade fire lines is closely related to building life-safety, an expert who specializes in cathodic protection should always be consulted regarding corrosion control of buried, metallic piping systems. Additionally, the local building authority having jurisdiction should also be consulted. For protection in severely aggressive soils, AWWA C105 covers materials and installation procedures for polyethylene encasement of underground installations of ductile iron piping for water.
A fire hydrant is the primary method by which the Fire Department accesses the underground fire-suppression water-service piping in the event of a fire. NFPA 24, Chapter 7, provides guidance for the type, quantity, size, outlet arrangements, location, and installation of fire hydrants. Dry barrel hydrants are within the scope of AWWA C502 and wet barrel hydrants are within the scope of AWWA C503. Fire hydrants, like all other fire suppression systems, are required by law to be inspected and tested at required intervals.
The basic design and operation method of a fire hydrant have not changed much over the last 150 years except for the days when they were called fire “plugs” because the hydrant was a wooden plug hammered into a wooden water main. Historically, most fire hydrants were “private” in that they were installed privately and supplied by cisterns, tanks, or other limited sources. Over the years, the concept of fire hydrants migrated to the municipal/governmental water utility or public water company. Over time and as municipalities became more aware of the cost (installation and maintenance) of providing fire hydrants, property Owners were again asked to provide the hydrants for their developments. Large hospitals, shopping malls, warehouse and distribution facilities, apartment complexes, etc. require numerous hydrants for readily accessible water supplies resulting in significant installation and maintenance costs.
Private fire hydrants are the responsibility of the property Owner. Many hydrants that are on private property are part of a larger fire protection system for that property. By law, the property Owner is required to test and maintain the hydrants on their property on a regular basis to ensure that they are functioning properly in the event of a fire emergency on that property.
Most public fire hydrants belong to each individual water department within a geographical area. They are responsible to test, exercise, and flush their hydrants. These hydrants are not only used by the Fire Department, but also by the water district to flush out the underground water mains when they have elevated levels of bacteria, discoloration of water, sand, or other problems in the underground fire-suppression water-service piping.
Dry barrel fire hydrants have obtained their name due to the fact that water is pumped or drained from the barrel when the hydrant is not in use. Dry barrel hydrants are drained and pressurized via the actions of a main valve located in the hydrant base. The barrel is pressurized when the main valve is opened and drained when the main valve is closed. This hydrant is especially suited to climatic conditions subject to freezing and can be used almost anywhere. A single main valve is located within the hydrant base adjacent to the inlet connection. The hydrant is also equipped with a drain valve that is automatically operated. The drain valve automatically opens, when the main valve is closed, draining all of the water from the hydrant barrel. The drain valve automatically closes when the hydrant is opened. In order to protect the hydrant from freezing, the main valve is located below the frost line which allows the hydrant to be used almost anywhere. There are three variations of dry barrel hydrants as follows:
- Compression Type: The main valve moves reciprocally on a vertical axis to and from a seat which is located in the hydrant base. The valve moves away from the seat to open and against the seat to close. It is moved by a vertical stem which moves up and down when the operated nut is rotated. The valve may be located above the seat and open with the pressure or below the seat and open against the pressure.
- Toggle Type: The main valve moves reciprocally on a horizontal axis away from or against a vertical seat located in the hydrant base. A vertical stem that has right and left hand threads moves the main valve. The rotation of the vertical stem causes the arms of the toggle mechanism to move the main valve which moves against the seat to close and away from the seat to open.
- Slide-Gate Type: The main valve consists of a gate that moves vertically via a threaded stem. The internally threaded gate moves when the stem is rotated. A wedging mechanism forces the gate against the valve seat. The valve seat is installed in the hydrant base.
Wet barrel fire hydrants operate similarly to dry barrel hydrants but with the barrel constantly filled with water. Each outlet on a wet barrel needs to be opened in order to get water from it. These types of hydrants are only used in warmer climates where freezing weather is not a concern. Numerous advantages which make this hydrant very popular are as follows:
- Simple in construction with all mechanical parts located above grade and accessible.
- If final grading resulting from new construction is different from the original plans, the hydrant can be easily lowered or raised by removing or adding sections to the proper height without expensive modifications.
- Adding a second or third hose line to the hydrant during a fire will not require a shut-down because of independent valve operation.
- Childproof caps which prevent dropping foreign objects down the body.
- Easy reconditioning resulting in minimum out-of-service time.
- Life expectancy of over 100 years for well constructed hydrants.
All fire hydrants in many states in the USA have a common type of thread on the hydrant outlets. These threads are National Standard Threads. Every Fire Department within any city in one of these states has the same threads on their fire hoses so they can connect to any available fire hydrant. This is crucial as it allows all the different Fire Departments to provide mutual aid to neighboring cities or counties in the event of a large fire emergency.
The potable water supply that is connected to the fire service main will need to be protected by some type of backflow prevention device. Backflow can occur either by “back siphonage” or by “back pressure”. “Back siphonage” is the reversal of water flow in the water supply line which is primarily caused by a water main break.”Back pressure” occurs when the pressure in the downstream piping rises above the incoming water supply pressure. This may result in a reversal of the water flow. This can be caused by elevated water storage tanks, thermal expansion, or pumps. The style and type of backflow protection varies with the design of the fire protection system, local conditions and requirements (local water authority), and water supply.
Quite often, the use of single check valves, detector check valves, and detector check valves are generally considered to be acceptable equipment, only to find out that they are not an “approved means” of backflow prevention by the Building Authority Having Jurisdiction which may consider many variations of backflow prevention. As an example, more sophisticated backflow prevention in the form of a reduced pressure type backflow preventer may be considered when a foam water or antifreeze sprinkler system is involved. To further complicate the issue, the American Water Works Association (AWWA) and NFPA 24 present differing options on backflow prevention.
- AWWA defines six(6) classifications for cross connection or backflow prevention which are based on the water source and arrangement of supplies where each classification or scenario can be based on the following:
- 1) Single check valve.
- 2) Double check valve with detector check.
- 3) Reduced-pressure backflow assembly.
- Additional consideration must be given when the use of a fire pump or jockey pump is included in the design.
- NFPA 24 states that various backflow prevention regulations accept different devices at the connection between public water mains and private fire service mains. The following devices (or combination thereof) could either be installed in a pit or be prohibited by local regulations from being installed in a pit:
- 1) Gravity check valve.
- 2) Detector check valve.
- 3) Double check valve assembly.
- 4) Reduced-pressure zone (RPZ) device.
- 5) Vacuum breaker.
In summary, when deciding on the proper backflow prevention, a careful and exhaustive review of all conditions including the complete fire protection system (including the use of antifreeze systems, combination chemical and water hood suppression system, foam systems, etc.) in addition to consultations with the Building Authority Having Jurisdiction are vital before a decision can be made regarding the proper backflow prevention for the fire protection system. When meeting with the Building Authority Having Jurisdiction, the following items may need to be addressed regarding the backflow preventer in order for them to render a decision:
- Possibility of any water damage.
- High hazard or low hazard application.
- Anticipated pressure loss through the device.
- Obstacles to on-going testing and maintenance.
- Freeze protection.
- Proximity to any new electrical equipment.
- Adequacy of drainage capability.
- Level of on-going service required.
- Possibility of back-pressure.
- Presence of downstream control valves.
- Will the device be used as a point of use installation?
- Possibility of a remote location.
Throughout several developed countries water meters are used to measure the amount of water used by commercial buildings which are supplied with water from a public water utility. These meters can be used at the water source (tapping location at the water utility supply line), well, or throughout the site water system to determine water flow through a particular part of the system such as the fire water service line dedicated to the building fire suppression system including the fire hydrants, etc., and free-standing fire department connections. In most of the world water meters water flow is measured in cubic meters (cu m) but in the USA and some other countries, water meters are calibrated in cubic feet (cu ft) or US gallons on an electronic or mechanical register. Some electronic meter registers have the option of displaying flow rate in addition to total usage. Several types of water meters are in common use. The kind of meter that needs to be used is dependent on the type of end user, flow measurement method, required flow rate, and accuracy requirements. The American Water Works Association establishes the standards for manufacturing water meters in North America.
Water meters are generally owned, read, and maintained by the public water utility such as a city, rural association, or private water company. The Owner of an apartment complex, commercial building, or building-campus is generally billed by a water utility based on the reading of one meter for the building site and one meter for the irrigation system serving the landscaping, with the costs shared among the tenants based upon some sort of key measure (size of rental unit, number of inhabitants), or by separately tracking the water consumption of each unit in what is called sub-metering. They are also used for sub-metering water consumption for fire hydrants and the fire water suppression line resulting from testing, repair, maintenance, system leakage, etc.
Displacement water meters are most often used in small commercial applications. Displacement water meters are commonly referred to as “Positive Displacement”, or “PD” meters. The two common types are the nutating disk meter and the oscillating piston meter. Either type relies on the water to physically displace the moving, measuring element in direct proportion to the amount of water that passes through the meter. The disk or piston moves a magnet that drives the register. The size of PD meters range from 5/8 inch (18 DN) to 2 inch (50 DN). In general, they are very accurate at low-to-moderate flow rates for small commercial applications. Since these meters are designed to require the water flow to “push” the measuring element, they have limited application on large commercial projects that require high flow rates or low pressure drops. PD meters are typically equipped with a built-in strainer which protects the measuring element from rocks and other debris that could break or stop the measuring element. The meter body is usually constructed of plastic, brass, or bronze material with internal, measuring chambers constructed of stainless steel and molded plastic.
Turbine meters are less accurate than jet and displacement meters at low flow rates, but the measuring element does not occupy or severely restrict the entire path of flow. In general, the direction of flow is straight through the meter which allows for higher flow rates and less pressure drop than displacement-type meters. These meters are preferred by large commercial users, as master meters for the site water distribution system, and fire protection systems. Strainers are usually required to be installed in front of the meter to protect the measuring element from gravel and other debris that could enter the water distribution system. Turbine meters are typically available for 1-1/2 inch (40 DN) to 12 inch (300 DN) or higher pipe sizes. Meter bodies are usually constructed of cast iron, ductile iron, or bronze. Internal turbine elements are available in plastic or non-corrosive metal alloys. In normal working conditions they are accurate but are greatly affected by the flow profile and fluid conditions.
- Fire meters are a specialized type of turbine meter meeting the high flow rate requirements for fire protection. They are often approved by Underwriters Laboratories (UL) or Factory Mutual (FM) for use in fire suppression systems.
- Fire hydrant meters are a specialized type of portable turbine meter that is attached to a fire hydrant to measure the water flow out of the hydrant. The meters are typically manufactured from aluminum for less weight and usually with a 3 inch (80 mm) capacity (connection). They are often required by the water utility for measuring water used on construction sites, for pool filling, etc. before the permanent meter has been installed.
Compound meters are used where high flow rates are required and where at times there are also smaller flow rates that require accurate measurement. These types of meters have two measuring elements and a check valve to regulate flow between them. At high flow rates, water is normally diverted primarily or in total to the turbine part of the meter. When the flow rate drops to where the turbine meter cannot measure accurately, a check valve closes to divert the water to a smaller meter which can measure the lower flow rate more accurately. The low flow meter is typically a multi-jet or PD meter. By adding the values registered by the high and low meters, the utility has a record of the total consumption of water flowing through the meter.
Registers on water meters consist of several types. A standard register normally has a dial similar to a clock, with gradations around the perimeter to indicate the measuring unit and the amount of water used, if less than the lowest digit in a display similar to the odometer wheels in an automobile, their sum being the total volume used. Modern registers are normally driven by a magnetic coupling between a magnet in the measuring chamber attached to the measuring element and another attached to the bottom of the register. Gears in the register convert the motion of the measuring element to the proper usage increment for display on the sweep hand and the odometer-style wheels. Many registers also have a leak detector. There is a small visible disk or hand that is geared closer to the rotation speed of the drive magnet, so that very small flows that would be visually undetectable on the regular sweep hand can be seen.
- With Automatic Meter Reading, manufacturers have developed pulse or encoder registers to produce electronic output for radio transmitters, data logging devices, and reading storage devices. Pulse meters send an analog or digital electronic pulse to a recording device. Encoder registers have an electronic means which permits an external device to interrogate the register to obtain either a stored electronic reading or the position of the wheels. Frequent transmissions of consumption data can be used to provide smart meter functionality.
- Specialized types of registers such as meters with an LCD display in lieu of mechanical wheels, and registers to output data pulses or data to a variety of controller and recording devices. For industrial applications, output is often 4-20 mA analog for recording or controlling different flow rates in addition to totalization.
- Different resolutions of the reading are indicated by different size meters. One rotation of the sweep hand may be equivalent to 10 gal (1 cu ft) (0.10 cu m) to 1,000 gal (100 cu ft) (10 cu m). If one rotation of the hand represents 10 gal (1 cu ft) (0.10 cu m) the meter has a 10 gal (1 cu ft) (0.10 cu m) sweep. Sometimes the last number(s) of the wheel display are non-rotating or printed on the dial face. The fixed zero number(s) are represented by the position of the rotating sweep hand. For example, if one rotation of the hand is 10 gal (1 cu ft)(0.10 cu m), the sweep hand is on 7, and the wheel display shows 123456 plus a fixed zero, the actual usage would be 1, 234, 567 gal (165, 038 cu ft) (4673 cu m). In the United States most utilities bill only to the nearest 100 gal (10 cu ft) (1 cu m) or 1,000 gal (100 cu ft) (10 cu m), and often only read the leftmost 4 or 5 numbers on the display wheels. Using the aforementioned example, they would read and bill 1,234, rounding to 1,234,000 gal based on a 1,000 gal billing resolution. The most common rounding for a particular size meter is often indicated by differently colored number wheels, the ones ignored being black, and the ones used for billing being white.
Tracer Wire Systems Specification Guidelines:
Provisions have been made under ACCESSORIES in Section 21 2200 for the Specifications Writer to build an appropriate specification for tracer wire systems consistent with the requirements of the Water Utility or the Local Authority Having Jurisdiction.
Most facility water service piping specifications call out the fire hydrant specifications down to the threads on the riser, but historically, the emphasis on detailed tracer wire specifications has been much less with very broad specifications. Depending on the geographical location of the project, some water utility departments do not even use tracer wire. The various options currently being used are detectable tape, warning tape, stranded copper, stranded stainless steel, coated solid copper, bare copper, copper clad steel, and stainless steel. Just what are the correct products to specify? The type of wire is important but is only part of the overall system. Other important concerns involving acceptable installation practices are the proximity to the pipe, wire termination, and proper wire connections when spicing or connection to the power supply.
Historically, the typical tracer wire specification has not been as thorough as it could be. As an example, simply stating “Install #12 solid copper wire with jacket” could result in sourcing the material from an electrical wholesaler or local lumber yard, and ending up with the least costly wire, usually THHN (Thermoplastic High Heat-resistant Nylon coated) wire. The nylon PVC coating on THHN wire will typically last around two years before it deteriorates and exposes the copper. Since THHN wire is not made for direct bury applications, the copper, over a period of time, will turn back to its original state or earth, resulting in disappearance of the locate signal. Articles authored by engineers and regulatory agencies starting over ten years ago have consistently warned of the improper use of THHN wire as part of the tracer wiring. When developing a tracer wire specification for your project, the following items need to be taken into account for the particular Jurisdiction of the project location:
- Wire Type: Copper clad steel, copper, stainless steel.
- Wire size or gauge (AWG).
- Jacket color and coating.
- Proper connections.
- Location of the wire in relation to the pipe.
- Connections, test stations, and wire termination methods.
- Provide specifications for open ditch/direct bury, pipe bursting, and directional boring.
- Larger diameter is normally called out for strength, not signal carrying qualities. Breakage is a common failure occurring during the installation. High strength copper clad steel (CCS) has twice the break load of solid copper which allows smaller diameter wire to be used, usually resulting in cost savings.
- Color: Adhere to the APWA (American Public Works Association) Uniform Color Code.
- Specify the appropriate jacket from many different, available types. Example: High density polyethylene (HDPE) or high molecular weight polyethylene (HMWPE) are designed for direct bury. Nylon is not.
- Solid copper or copper clad steel (CCS) work well and there’s no need for stranded. High strength copper clad steel (CCS) was introduced to the market in 2004 for tracer wire and it has a 2X strength advantage over solid copper. Copper clad steel has equal conductivity to solid copper and stainless, but is usually less expensive.
- Proper connectors, which protect from moisture and corrosion, are extremely important. Do not twist the wires together and wrap with electrical tape. Corrosion will happen eventually and the locate signal will be lost to ground at the connection.
- Install the tracer wire in the same orientation to all installed pipe. Using a spacer, taping the tracer wire to the pipe every 8-10 feet in the three o’clock position or specifying fill between the pipe and tracer wire are acceptable practices. Taping the wire to the pipe will help to prevent damage to the wire during back filling or future digging around the pipe. Installation of color coded warning tape one foot above the pipe will enhance utility ID during excavation when repairs are needed. Once tape has been found, only hand digging should be allowed.
- An acceptable and fully operational tracer wire system is connected with electrical current characteristics in mind. Electricity will take the path of least resistance. Good grounding and terminating of the wire will improve the quality of the signal. If possible, using test stations to bring the tracer wire above ground for ease of terminating a signal is best. Introducing a small anode or grounding one or both ends of the wire may enhance signal strength.
- Different installation applications call for different types of wire. Open ditch/direct bury does not require as strong a wire as directional drilling or pipe bursting. Consider strength and coating type and thickness when specifying wire, making sure there will be no surprises after the project is completed or when locating is required.
- It is very important to verify that the contractor or city inspector perform a “locate” or “conductivity test”, and to promptly correct any issues prior to signing off on the project instead of performing the “locate” months or years later and the piping cannot be found.
- Like your fire hydrant, curb stop, manhole, piping and other important components of your system, tracer wire should be taken just as seriously. It’s one inexpensive insurance policy, especially if you weigh the cost of repairs from a damaged utility due to not being able to locate it. A good specification needs to cover the entire tracer wire system, not just wire, but connectors, test stations, and installation procedures. Please keep in mind that THHN wire is not suitable for direct bury applications.
ASSE 1060 was originally published in 1996. This document is the result of detailed input from numerous experts in the field and also provides an excellent foundation for additional development of engineering specifications in addition to Water Authority and Utility ordinances and policies. The legal profession also recognizes this Standard as an excellent tool in the defense against illegitimate claims and law suits involving inadequate protection of the backflow prevention assembly integral to public and private fire lines. The Enclosure Industry is almost 20 years old from the standpoint of commercially developed and marketed products that provide controlled, interior environments in addition to force protection against theft, vandalism, and other elements that could compromise satisfactory operation of the valve.
The Enclosure Industry saw its humble beginnings with the advent of a small box of fiberglass construction, designed to drop over the valve assembly to a fully engineered, insulated enclosure equipped with thermostatically controlled heat for freeze protection, properly sized drains for the potential RPZ discharge, power outage/low temperature alarms, door locking mechanisms, including aesthetic designs for high profile installation, custom designs for combination equipment, simple field installation, national distribution network, established manufacturers, and training programs that produce “Enclosure Specialists” as field consultants.
OSHA (Occupational Safety and Health Administration) introduced the “Confined Spaces” compliance program in 1993 which involves the protection of employees from injury or death resulting from a work area that limits exit and entry and which may have a hazardous atmosphere or interior hazard of another type. The program involves costly training, equipment, and administrative support to achieve compliance. Fines up to $70,000.00 per violation can be imposed and extensive liabilities incurred due to a death or serious injury. In many situations, above ground enclosures have been excluded from confined spaces compliance and are being used extensively as an alternative to confined space installations.
RPZ type backflow preventers discharge large amounts of water due to a fouled check or a full backflow condition. Several valve manufacturers have reported discharge rates of 500 gal/min (30 L/sec) in areas such as warehouses, basements, ceilings, electrical equipment rooms, and other systems that are sensitive to large quantities of water. Not having adequate drainage, discharge water can accumulate quickly in adjoining areas of the valve. As an example, 5000 gal (19,000 liters) of water can be discharged from a fouled RPZ in ten minutes. A 4 inch (100 DN) drain can handle approximately 100 gal/min (6 L/sec) leaving 4,000 gal (15,000 liters) in the area that weighs 32,000 pounds (14,500 kg). In summary, an above ground outdoor enclosure totally eliminates this particular hazard to the building, inventory, equipment, files, including furniture and floor coverings.
As the demand for enclosures and their specifications became more frequent, increased activity became evident from the producers of related fiberglass productions in addition to the contractors supplying heated, outdoor installations. Enclosures then began to appear subject to varying degrees of success, coupled with a wide range of aesthetics, but without adequate access for testing. Provisions for drainage were non-existent, too small, or too large. Insulation also ranged from not enough to having too much for the site location. In the more northern climates requiring freeze protection, heat sources were unsafe and/or insufficient. Sizing was based on a random selection which did not take the many multiple and special applications into account. The special design segment of this industry approached 50% of production, however, many manufacturers that were engaged in special design failed due to insufficient design capability and inadequate planning. The manufacturers that did succeed evolved to extensive ACAD computer programming and close working relationships with valve manufacturers to insure proper clearances for testing and installation.
As the Enclosure Industry evolved, many Water Authority and Water Utility Departments realized the value of enclosures and local ordinance and policies were developed requiring above-ground, heated enclosures for several installations. The outdoor enclosure became a recommended installation throughout the United States in areas subject to vandalism and freezing conditions. The Enclosure Industry continued to expand with national distribution networks and manufacturer’s representative organizations that involved reps for major manufacturers of backflow prevention valves. The development of this Industry spearheaded the development of a national standard by a recognized authority for outdoor enclosures. As a major player in the continued emphasis on backflow prevention coupled with the inherent challenge of where to locate the valve, the utility segment in addition to design engineers required a base-line to work with to insure adequate protection and reliability. ASSE 1060 has provided the Enclosure Industry a giant step in this effort. In order to obtain certification for their enclosures, manufacturers need to provide evidence of proper testing to standards in the following areas:
- Drainage performance.
- Freeze protection.
- Structural design.
- Air inlet volume.
- Testing and maintenance access.
- Hinged access panel restraints, includes removable panel weight restrictions.
- Materials specifications i.e. exterior, interior, hardware, and fasteners.
- Elastomer UV exposure.
- Security and vandalism.
- Manufacturer identification and specifications.
- Installation instructions.
The enclosures are tested for performance in several classes:
- Freeze protection enclosures.
- Freeze retardant enclosures.
- Non-freeze protection enclosures.
The testing process can be conducted only at ASSE approved laboratories. The process takes about 60 days. The largest unit produced must be tested and approved for certification of the product line.
Editing of Section 211100 is designed to start in PART 2, progress to PART 3, and finish up with PART 1.
The various piping materials used in facility fire suppression water service piping including valves, fire department connections, private fire hydrants, water meters, bedding and cover materials, polyethylene jacketing, and accessories comprise the main paragraphs in PART 2. When a particular item is activated in PART 2 for use in the project, the appropriate paragraph listed under SECTION INCLUDES is activated. Related articles and optional text in PARTS 1 and 3 will be activated as well.
When a particular article or paragraph in PART 2 and PART 3 that contains a reference standard is chosen, the corresponding standard cited under REFERENCE STANDARDS in PART 1 is activated. If the Consolidated List of Citations option is active, cross sectional links (not visible in the links window) will activate the reference standard in Section 01 4219 – Reference Standards as well.
When a particular article or paragraph in PART 2 and PART 3 that cites another section is chosen, the corresponding Section listed under PART 1 – RELATED REQUIREMENTS is activated. Certain Sections listed under PART 1 – RELATED REQUIREMENTS are not cited in either PART 2 or PART 3 but are listed under RELATED REQUIREMENTS because they include items that might be expected to be found within this Section or include action items important for the completion of the work that are not specified in an obvious location (e.g. isn’t obvious from the section title).
All optional text and choices under PART 2 include a fill-in to accommodate any updates that listed manufacturers may offer but are not shown in the choice options. Default options for choices are based upon what would be reasonable for the application. The content of PART 2, including the choices, has been structured to accommodate listed manufacturers.