Expansion Tanks for Antifreeze Systems

Unheated areas are typically covered by dry systems or with antifreeze systems. These areas may experience a wide range of temperatures over a period of time. Higher temperatures will cause the antifreeze to expand and thereby increase the pressure of the system. When a backflow prevention device is installed between the antifreeze system and the wet pipe system, this pressure may increase to the point of system failure resulting in leaks or burst fittings & pipe. NFPA 13, (2010 edition), section 7.6.3.2 addresses this potential problem by requiring the use of an expansion chamber/tank.

The expansion tank is essential for successful system operation when a backflow prevention device is installed between the antifreeze system and the wet pipe system, (or if the entire system is antifreeze). The expansion tanks are required by 6.1.1.2 to be listed for fire sprinkler system use.

At this time, our office is aware of only two manufacturers that have UL approval on expansion tanks for NFPA 13 systems. One is Young Engineering Manufacturing, Inc. out of California at 909-394-3225. They have an East Coast distributor at Atlantic American Fire Equipment, 508-839-7400. The other is Amtrol out of Rhode Island at 401-884-6300. Also be aware that these tanks come with a minimum pre-charge, and this pre-charge has to be increased as per the manufacturer's specification for the specific application. Then this charge needs to be inspected periodically as per standard inspection requirements. The proper size tank must also be purchased for a particular antifreeze system.

The 2010 edition of NFPA 13 requires a test and drain connection at the remote portion of the system for systems with more than 40 gallons of antifreeze solution. This requirement can be found in section 7.6.3.6, and comes from NFPA 25, which requires the concentration levels to be checked at both ends of the system.

NFPA 13R, (2010 edition), section 5.4.3 requires antifreeze systems to be installed according to NFPA 13, which means that the expansion tanks must also be listed when used in NFPA 13R antifreeze systems.

Hydro-Pro, Maine Life Safety, and NFPA 13D standards do not require tanks to be listed for fire sprinkler system use. Our office however will only accept standard non-listed, lower-quality expansion tanks for these standards when the total antifreeze solution does not exceed 40 gallons. When antifreeze solutions exceed 40 gallons in those systems, then only expansion tanks listed for fire sprinkler system use will be accepted for these standards. NFPA 13 and 13R systems, however, always require the tanks to be listed for fire sprinkler system use, regardless of antifreeze solution volume.

When an antifreeze loop comes off a wet pipe system, and the check valve has a 1/32" hole in it, according to Figure 7.6.3.1 in NFPA 13, then an expansion tank is not required, however the assumption is that the wet pipe system is large enough in volume to absorb the pressurized antifreeze. NFPA does not mention this, but in Maine an expansion tank on the antifreeze system is also required to be installed whenever the volume of the antifreeze system exceeds the volume of the wet pipe system that it flows back into. The exception to this would be if engineering data can be supplied to otherwise justify the omission of the expansion tank.

Fire Sprinkler Industry, please take careful note of this handout before bidding. Expansion tanks listed for fire sprinkler systems are very expensive. I will see to it that the bidding field is level in this area, with no exceptions, so please do not overlook this very important part of your system design. Pressure-relief valves are not allowed in place of expansion tanks because they lead to dilution of the antifreeze solution.

Antifreeze systems installed without expansion tanks where they are required, are very susceptible to leaks and burst fittings, jeapordizing fire safety, and causing great inconvenience and cost to clients, not to mention generating negative publicity for fire sprinkler systems. Enforcement action will be taken against fire sprinkler contractors who omit the expansion tank where required, or who install a non-listed expansion tank where one is required to be listed for fire service. Where required, the listed expansion tank is an important design feature, critical to the reliability of the fire sprinkler system operation.

Antifreeze Policy 9-6-11

The National Fire Protection Association under the direction of their Standards Council issued Tentative Interim Amendments (TIAs) 8-16-10 to ban antifreeze from NFPA 13D systems, and also from the residential portion of NFPA 13R and NFPA 13 systems based on a series of fire tests regarding the flammability of antifreeze. Investigation continues on this issue and NFPA has since developed other TIAs and is likely to come up with changes in future editions.

Meanwhile, here is our updated policy with the first 4 items below addressing new antifreeze systems in residential portions of NFPA 13D, NFPA 13R & NFPA 13, and the last 2 items addressing existing antifreeze systems. This policy does not apply to non-residential portions of buildings such as attics, garages, storage areas, mechanical spaces, canopies, etc.:

1. In new systems do not use antifreeze in NFPA 13D systems or in residential portions of occupancies in NFPA 13 & 13R systems. Our office however reserves the right to permit antifreeze in special cases within specific guidelines as outlined below where there is no other viable alternative and where the lack of its use would create a more hazardous situation.

The viable alternatives to use instead of using antifreeze include things such as: running pipe in heated areas, using insulation in proper quantities with approved installation methods, using dry pendents or dry horizontal sidewalls in the cold area, using a dry system, (Tyco now has residential heads that are listed for dry systems), using nitrogen, or changing the building design so that the space becomes heated. Communicate with builders and owners on the importance of minimizing cold areas by providing insulation and a heat source where possible early on in the project.

2. When new antifreeze systems are approved for these residential portions of occupancies then minimize the extent of them. For example don’t use antifreeze for the whole building if you only need antifreeze for just a portion of the building.

3. When new antifreeze systems are installed in residential portions of occupancies, then avoid long pipe drops and use glycerin rather than propylene glycol.

4. When new antifreeze systems are installed in residential portions of occupancies don’t use more than 50% antifreeze in the mixture and use only premixed solutions. If this concentration is not adequate freeze protection for the temperatures anticipated then revert back to item #1 above.

5. When inspecting existing antifreeze systems in residential portions of occupancies dilute over-concentrated systems to acceptable levels when freeze protection is not jeopardized for the temperatures anticipated. When that is impractical, then discuss options in item #1 above with the client. Existing antifreeze systems however may be maintained at concentrations for the original design, as per the retroactivity clauses found in chapter 1 of NFPA 13, 13D, & 13R.

6. The retroactivity clauses do not require changes to be made to existing antifreeze systems retroactively when the system met requirements at the time of installation, unless the authority having jurisdiction believes that there is a situation that presents an unacceptable degree of risk. The line drawn for an unacceptable degree of risk is those buildings licensed with the Department of Health and Human Services, (predominantly nursing homes, hospitals and day care centers), where the concentrations of antifreeze are high and the static pressures exceed 100 psi. These situations need to come up with a plan to minimize the risk. When guidance is needed to develop a plan of correction, then please contact us.

[Last Updated 1-11-12 to reflect currently adopted standards with their references. Previous updated 9-6-11 where the hange included consolidating items from the technical policy and addressing existing systems in colder areas of Maine and being more specific. Generally speaking this was a total revamp & enlargement. Previously updated 12-8-10. Prior to that it was updated 2-23-10 when it was first added to this web page.]

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Higher temperatures will cause the antifreeze to expand and thereby increase the pressure of the system. When a backflow prevention device is installed between the antifreeze system and the wet pipe system, this pressure may increase to the point of system failure resulting in leaks or burst fittings & pipe. NFPA 13, (2010 edition), section 7.6.3.2 addresses this potential problem by requiring the use of an expansion chamber/tank. The expansion tank is essential for successful system operation when a backflow prevention device is installed between the antifreeze system and the wet pipe system, (or if the entire system is antifreeze). The expansion tanks are required by 6.1.1.2 to be listed for fire sprinkler system use. At this time, our office is aware of only two manufacturers that have UL approval on expansion tanks for NFPA 13 systems. One is Young Engineering Manufacturing, Inc. out of California at 909-394-3225. They have an East Coast distributor at Atlantic American Fire Equipment, 508-839-7400. The other is Amtrol out of Rhode Island at 401-884-6300. Also be aware that these tanks come with a minimum pre-charge, and this pre-charge has to be increased as per the manufacturer's specification for the specific application. Then this charge needs to be inspected periodically as per standard inspection requirements. The proper size tank must also be purchased for a particular antifreeze system. The 2010 edition of NFPA 13 requires a test and drain connection at the remote portion of the system for systems with more than 40 gallons of antifreeze solution. This requirement can be found in section 7.6.3.6, and comes from NFPA 25, which requires the concentration levels to be checked at both ends of the system. NFPA 13R, (2010 edition), section 5.4.3 requires antifreeze systems to be installed according to NFPA 13, which means that the expansion tanks must also be listed when used in NFPA 13R antifreeze systems. Hydro-Pro, Maine Life Safety, and NFPA 13D standards do not require tanks to be listed for fire sprinkler system use. Our office however will only accept standard non-listed, lower-quality expansion tanks for these standards when the total antifreeze solution does not exceed 40 gallons. When antifreeze solutions exceed 40 gallons in those systems, then only expansion tanks listed for fire sprinkler system use will be accepted for these standards. NFPA 13 and 13R systems, however, always require the tanks to be listed for fire sprinkler system use, regardless of antifreeze solution volume. When an antifreeze loop comes off a wet pipe system, and the check valve has a 1/32" hole in it, according to Figure 7.6.3.1 in NFPA 13, then an expansion tank is not required, however the assumption is that the wet pipe system is large enough in volume to absorb the pressurized antifreeze. NFPA does not mention this, but in Maine an expansion tank on the antifreeze system is also required to be installed whenever the volume of the antifreeze system exceeds the volume of the wet pipe system that it flows back into. The exception to this would be if engineering data can be supplied to otherwise justify the omission of the expansion tank. Fire Sprinkler Industry, please take careful note of this handout before bidding. Expansion tanks listed for fire sprinkler systems are very expensive. I will see to it that the bidding field is level in this area, with no exceptions, so please do not overlook this very important part of your system design. Pressure-relief valves are not allowed in place of expansion tanks because they lead to dilution of the antifreeze solution. Antifreeze systems installed without expansion tanks where they are required, are very susceptible to leaks and burst fittings, jeapordizing fire safety, and causing great inconvenience and cost to clients, not to mention generating negative publicity for fire sprinkler systems. Enforcement action will be taken against fire sprinkler contractors who omit the expansion tank where required, or who install a non-listed expansion tank where one is required to be listed for fire service. Where required, the listed expansion tank is an important design feature, critical to the reliability of the fire sprinkler system operation. Antifreeze Policy 9-6-11 The National Fire Protection Association under the direction of their Standards Council issued Tentative Interim Amendments (TIAs) 8-16-10 to ban antifreeze from NFPA 13D systems, and also from the residential portion of NFPA 13R and NFPA 13 systems based on a series of fire tests regarding the flammability of antifreeze. Investigation continues on this issue and NFPA has since developed other TIAs and is likely to come up with changes in future editions. Meanwhile, here is our updated policy with the first 4 items below addressing new antifreeze systems in residential portions of NFPA 13D, NFPA 13R & NFPA 13, and the last 2 items addressing existing antifreeze systems. This policy does not apply to non-residential portions of buildings such as attics, garages, storage areas, mechanical spaces, canopies, etc.: 1. In new systems do not use antifreeze in NFPA 13D systems or in residential portions of occupancies in NFPA 13 & 13R systems. Our office however reserves the right to permit antifreeze in special cases within specific guidelines as outlined below where there is no other viable alternative and where the lack of its use would create a more hazardous situation. The viable alternatives to use instead of using antifreeze include things such as: running pipe in heated areas, using insulation in proper quantities with approved installation methods, using dry pendents or dry horizontal sidewalls in the cold area, using a dry system, (Tyco now has residential heads that are listed for dry systems), using nitrogen, or changing the building design so that the space becomes heated. Communicate with builders and owners on the importance of minimizing cold areas by providing insulation and a heat source where possible early on in the project. 2. When new antifreeze systems are approved for these residential portions of occupancies then minimize the extent of them. For example don’t use antifreeze for the whole building if you only need antifreeze for just a portion of the building. 3. When new antifreeze systems are installed in residential portions of occupancies, then avoid long pipe drops and use glycerin rather than propylene glycol. 4. When new antifreeze systems are installed in residential portions of occupancies don’t use more than 50% antifreeze in the mixture and use only premixed solutions. If this concentration is not adequate freeze protection for the temperatures anticipated then revert back to item #1 above. 5. When inspecting existing antifreeze systems in residential portions of occupancies dilute over-concentrated systems to acceptable levels when freeze protection is not jeopardized for the temperatures anticipated. When that is impractical, then discuss options in item #1 above with the client. Existing antifreeze systems however may be maintained at concentrations for the original design, as per the retroactivity clauses found in chapter 1 of NFPA 13, 13D, & 13R. 6. The retroactivity clauses do not require changes to be made to existing antifreeze systems retroactively when the system met requirements at the time of installation, unless the authority having jurisdiction believes that there is a situation that presents an unacceptable degree of risk. The line drawn for an unacceptable degree of risk is those buildings licensed with the Department of Health and Human Services, (predominantly nursing homes, hospitals and day care centers), where the concentrations of antifreeze are high and the static pressures exceed 100 psi. These situations need to come up with a plan to minimize the risk. When guidance is needed to develop a plan of correction, then please contact us. [Last Updated 1-11-12 to reflect currently adopted standards with their references. Previous updated 9-6-11 where the hange included consolidating items from the technical policy and addressing existing systems in colder areas of Maine and being more specific. Generally speaking this was a total revamp & enlargement. Previously updated 12-8-10. Prior to that it was updated 2-23-10 when it was first added to this web page.]

Bureau Information

Expansion Tanks for Antifreeze Systems

Antifreeze Policy 9-6-11