Fire Sprinklers FAQ

The liquid used in our glass bulb sprinklers is a non-toxic proprietary glycerin solution that expands when heated.

The different colors designate various temperature classification ratings in accordance with NFPA 13.

The different size bulbs relate to the Response Time Index (RTI) of the sprinkler. This measure determines the type of sprinkler response. 5mm bulbs are used for standard response sprinklers, 3mm bulbs are used for quick response sprinklers, and 2.5mm bulbs are used for ESFR's and Fixed Temperature Release Pilot Line Detectors (PLD).

The RASCO marking is indicative of a Reliable manufactured product. Additional information can be found on the sprinkler deflector.

Reliable offers several corrosion resistant coatings and sprinklers manufactured from stainless steel. Most sprinklers are available with a polyester coating in various colors. In addition, for standard response sprinklers we offer 165°F clear wax, 212°F brown wax (for intermediate temperature rated sprinklers), lead plated, and wax over lead coatings. Most glass bulb sprinklers are also available with an electroless nickel PTFE (ENT) finish. Reliable ENT finish sprinklers are cULus Listed and, in some cases, FM Approved as Corrosion Resistant Sprinklers. The technical bulletin for each sprinkler will provide details on corrosion resistant finishes and applicable listings.

Standard spray sprinklers, such as the Model F1 series, Model F1FR series, and Model G series are control mode/density area sprinklers available with different orifice sizes and K-Factors. The amount of water discharged is dependent on the spacing and density requirements in accordance with NFPA 13. The pressure to achieve that flow is based on the K-Factor of the sprinkler and the pressure available based the available water supply. You must calculate the pressure required using the formula P = (Q/K)². Alternately, if the pressure at the sprinkler is known, calculate the flow using the formula Q = K√(P). NFPA 13 requires a minimum starting pressure of 7 psi for most sprinklers.
Q = Flow (in gpm)
K = K-Factor
P = Pressure (in psi)

This depends on the sprinkler. Generally speaking, NFPA 13 has no height restrictions on the use of control-mode density-area (CMDA) sprinklers except in certain storage occupancies. Control mode specific application (CMSA) and early-suppression fast-response (ESFR) sprinklers used in the protection of storage are generally limited by specific roof or ceiling heights. Chapters 12 through 21 of NFPA 13 address the protection of storage using CMDA, CMSA, and ESFR sprinklers.

NFPA specifies the minimum spacing for sprinklers, but also states that sprinklers must be installed in accordance with their listing in the event that the listed minimum distance differs from the standard. Reliable indicates the minimum spacing on all sprinklers that differ from NFPA 13, NFPA 13R and NFPA 13D standards. If not shown in the bulletin, the minimum spacing is as allowed by the applicable NFPA standard.

Recessed and concealed sprinkler ceiling plates are required to be listed with the sprinkler, and used only in accordance with their listing. Mixing and matching of recessed trim and concealed ceiling plates is prohibited. Exposed or surface mount sprinklers can use any trim plate provided that the deflector distances specified in NFPA 13 are met.

The Reliable SWC concealed horizontal sidewall can be used in Light Hazard areas as defined in NFPA 13 and non-residential Light Hazard areas as defined in NFPA 13R. It is not a residential sprinkler, and therefore cannot be used in application requiring a listed residential sprinkler. You should always check for state or local requirements that might differ from the NFPA codes.

Starting with the 2010 edition of NFPA 13, the rules for discharge of large drop and control mode specific application (CMSA) sprinklers were combined. Large drop sprinklers are now considered to be a type of CMSA sprinkler. Reliable offers the Model N252 EC CMSA sprinkler (technical bulletin 908) that can be used in conjunction with NFPA 13 (2013) chapter 21 titled “Alternative Sprinkler System Designs for Chapters 12 Through 20.” The Model N252 EC CMSA enjoys significant water saving advantages compared to standard sprinklers and with the adoption of the 2015 International Fire Code, smoke and heat removal systems are no longer required. This makes the Model N252 EC CMSA an attractive option to other conventional protection schemes.

Yes, Reliable manufactures several styles of stainless steel sprinklers. Please reference Technical Bulletin 064 for stainless steel standard response sprinklers, Technical Bulletin 065 for stainless steel quick response sprinklers, and Technical Bulletin 178 for Extended Coverage Sprinklers.

Dry sprinklers should always be installed in the side outlet of a tee. The fitting on the dry sprinkler is designed to extend up into the fitting to prevent the accumulation of deposits on the inlet of the sprinkler. Dry sprinklers should never be installed in an elbow or coupling; this can impede operation and/or allow deposits to accumulate on the inlet of the dry sprinkler. NFPA 13 and our installation instructions specify the minimum exposed barrel length required inside the conditioned space depending on the anticipated temperatures of the conditioned and non-conditioned space. Recommendations are also provided on the appropriate technical bulletin for sealing the openings created by the dry sprinkler; if the freezer contains food products, make sure the sealant you use is FDA approved. Finally, NFPA 25 requires that dry sprinklers be inspected and tested every 10 years, and replaced if necessary.

Reliable has been a leader for years in solder link technology and solder links are used where appropriate. Solder link sprinklers are somewhat more robust and do not require plastic covers for protection during shipping and installation, saving our customers time and money. Glass bulb sprinklers are available where the needs for aesthetics or other design considerations dictate their use.

Reliable chose many years ago not to compete with our customers, and we do not compete with our customers today. Our mission is to provide customers the latest in quality fire sprinklers, valves, and related products manufactured by Reliable utilizing the latest technology. In addition, Reliable distributes other quality fire protection products manufactured by selected vendors.

Yes. An excellent choice for MRI rooms is the Reliable Model F4FR-NF, a non-ferrous concealed sprinkler specifically tested for use in MRI rooms. This is the only concealed sprinkler actually tested in a laboratory with a magnetic field of 6 Tesla. The highest clinical magnet system commercially available today produces a magnetic field of 3 Tesla.

Beginning in January of 2001, all manufacturers were required to assign an alpha-numeric code called the sprinkler identification number (SIN) to each sprinkler. This was to comply with the marking requirements stated in paragraph 3-2.2 of NFPA 13, 1999 edition. When used with the corresponding technical bulletin, the SIN number is used to verify the model, deflector style, K-Factor and thermal sensitivity of the sprinklers. Reliable SIN numbers begin with either "R" or "RA" and are followed by four numbers. The first two numbers identify the last two numbers of the Reliable technical bulletin associated with that sprinkler. The last two numbers identify the deflector style and the K-Factor range, respectively. All SIN numbers are located on the sprinkler deflector. "Pintle" screws (small metal protrusion extending above or beyond the sprinkler deflector), which were used to identify sprinklers using other than standard orifice/thread combinations, will be phased out.

The two numbers immediately following the “R” or “RA” refer to the bulletin number associated with the sprinkler. Prior to adoption of the SIN program in 2001, Reliable elected to use bulletin numbers 100 to 199 for our sprinklers with an “R” prefix for “Reliable.” As sprinkler technology evolved and more models entered the market, the initial 100 bulletin numbers were exhausted and it was necessary to begin again with “001.” Since only the last two digits of the bulletin number are used in the SIN, it became necessary to distinguish between “001” and “101.” This is accomplished by using the “RA” (Reliable Automatic) designation for the newer sprinklers. For example, information on a “R10xx” sprinkler would be found on Technical Bulletin 110, while information on a “RA10xx” sprinkler would be found on Technical Bulletin 010.

The sprinkler identification number (SIN) number is used only to verify the model, deflector style, K-Factor and thermal sensitivity of the sprinkler. The SIN does not identify the temperature rating, trim style, decorative finish and/or corrosion-resistant finish of the sprinkler. This level of information would result in a potentially infinite number of very long SINs that could not be reproduced on a relatively small device.

No, installation of the retaining flange is not a UL Listing requirement. The tamper resistant and self-injury prevention features of institutional sprinklers are not part of the UL Listing. They are design features provided by the sprinkler manufacturer. For maximum tamper resistance, it is the responsibility of the installing contractor to secure the nipple on which the sprinkler is installed to prevent the sprinkler and escutcheon assembly from being pulled away from the wall or ceiling. The retaining flange is provided as a way of securing the branch line piping, in the form of a nipple or arm-over, to prevent pipe movement initiated by the room occupant. If the retaining flange cannot be used due to larger piping or over-sized wall sleeves, alternative devices approved by the installing contractor or design engineer may be used to secure the piping from movement.

No, there are no listed/approved sprinkler guards for institutional sprinklers. By design, a sprinkler guard would provide an attachment point for an individual intent on inflicting self-injury. In addition, features for such a sprinkler guard would impede and hinder sprinkler performance.

No, there are no listed/approved sprinkler guards for extended coverage or residential sprinklers. Because of the extended discharge requirements and low flow characteristics associated with these types of sprinklers, the sprinkler guard would act as a significant obstruction to sprinkler performance, requiring greater flows and pressure to meet listing/approval requirements.

No, corrosion-resistant coatings adversely affect the sensitivity of the fast-response fusible link. Currently, corrosion resistant listings can only be obtained for quick-response sprinklers using a glass bulb thermal element.

Sprinkler temperature rating is based on the following:

  • Maximum expected ambient temperature a sprinkler will be exposed to on a daily (or seasonal) basis
  • Proximity of sprinklers relative to heat sources
  • Design densities chosen for storage applications based on storage area/density curves

NFPA 13 (2013) section 8.3.2 provides the information necessary for selecting the proper temperature rating for fire sprinklers with regard to ambient temperature and proximity to heat sources. Chapters 12 through 21 contain information about temperature selection of sprinklers used in storage occupancies.

Recent testing of residential sprinklers has shown that the listed flows and pressures for flat ceilings provide an acceptable level of protection in most sloped and/or beamed ceilings. The 2013 editions of NFPA 13D and 13R allow listed residential sprinklers to be installed at their listed flows and pressures for:

  • Flat, smooth, horizontal ceilings with no beams
  • Flat, horizontal beamed ceiling with beams up to 14” deep and sprinklers below the beams
  • Maximum 8:12 smooth, sloped ceiling with no beams
  • Maximum 8:12 sloped ceiling with beams up to 14” deep and sprinklers below the beams
  • Maximum 8:12 sloped ceiling with beams of any depth with sprinklers in each pocket created by the beams

Additional constraints apply to these brief descriptions, and it is the contractor’s responsibility to confirm all requirements from the appropriate NFPA standard with the Authority Having Jurisdiction.

Yes; however, sprinklers are tested and listed/approved by the foam manufacturers with a specific foam concentrate. You must reference the UL Fire Protection Equipment Directory section on Foam Liquid Concentrates (GFGV), the Factory Mutual Approval Guide, and/or the foam manufacturer's technical documentation to determine which sprinkler is listed/approved for use with the specific foam concentrate.

Yes, section of NFPA 13 (2016 edition) has clarified that it is acceptable to install sprinklers that carry listings for quick response and standard response for different coverage areas in the same compartment without any separation required.

No. Factory Mutual does not currently recognize any fully concealed sprinklers as quick response. This puts the responsibility on the local authority having jurisdiction (AHJ) to decide between satisfying the architect or FM Global. In most cases, the national NFPA standard will take precedence.

No. Concealed sprinklers are tested at the laboratory with a ceiling installed and rely on the surrounding ceiling to assist in the movement of heat past the thermal element. There is no testing protocol for concealed sprinklers to be installed without a ceiling.

No. Because of the large volume of water that ESFR sprinklers discharge, the obstruction created by a guard is relatively more significant and adversely impacts the distribution pattern of the sprinkler.

This issue is addressed in section of the 2016 edition of NFPA 13: Where replacing residential sprinklers manufactured prior to 2003 that are no longer available from the manufacturer and that are installed using a design density less than 0.05 gpm/ft2 (2.o4 mm/min), a residential sprinkler with an equivalent K-factor (± 5 percent) shall be permitted to be used provided the currently listed coverage area for the replacement sprinkler is not exceeded.

Most sprinklers can be identified using good quality photographs of the sprinkler and sprinkler deflector which can be emailed directly to Once identified, a copy of the appropriate technical bulletin will be provided. If not evident on the photographs, the year of sprinkler manufacture should be provided to insure the bulletin edition nearest the manufacturing date is selected.

The product solution sheet found at describes the standard finishes and special finishes available. In addition, cover plates can be custom painted at the factory to match the surrounding wall or ceiling. Information and pricing for custom painting is available from your local Reliable sales representative.

Information regarding storage, handling, and installation of sprinklers is found on the appropriate sprinkler Technical Bulletin and Caution Sheet 310.