One Systems Natatorium - Manual

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March 28, 2014
One Systems Natatorium (Indoor Swimming Pool)
Speaker Products Installation Manual
One Systems has developed a narrow focus, application specific set of products designed
for use in Natatorium (indoor swimming pool) environments. The 108IM/NAT and 112/NAT
are constructed using very high molybdenum content stainless steel for all internal and
external structural rigging members.
Indoor swimming pool environments can present very high relative humidity and harsh
chemical atmospheres. The combination of humidity and airborne chemical composition
restricts the mounting of the 112/NAT or 108/NAT to wall mounting in solid concrete or grout
filled block (CMU) concrete walls ONLY! One Systems does not allow wire rope suspension
of its products in Natatorium environments. Call One Systems regarding direct mounting to
the structural steel of the indoor swimming pool building (Galvanic isolation is required!).
One Systems offers recommendations for installation on solid concrete and grout filled block
walls. Contact One Systems for additional information.
Commonly used stainless steels such as 304-grade and 316-grade, known as austenitic
steels, offer good corrosion resistance and strength in harsh environments. Marine-grade
(specifically known as 316-grade stainless steel) offers additional protection in salt spray,
ocean front, and cruise ship applications. Unfortunately, these austenitic materials are
susceptible to chloride stress corrosion cracking (SCC). Both 304-grade and 316-grade are
susceptible to SCC. SCC is a particular problem in indoor swimming pool environments and
can result in structural failure of the rigging components. The chlorine based chemicals in
the water react with “human” by-products, such as sweat, and produce chloramines. These
chloramines and hydrolyzed byproducts pass into the atmosphere and are deposited on all
surfaces in the Natatorium. They are transported throughout the space via the air handling
system of the venue. This is particularly problematic in areas above the pool surface that are
not routinely washed down or cleaned. Loudspeakers and their associated rigging are
typically mounted far above the “splash zone” and these chloramines are left to settle on
structural surfaces, so that SCC can progress to critical levels. Unfortunately, there are no
established thresholds for chloramine exposure and associated stress levels in the structural
members, so SCC can be a significant concern in Natatorium environments. Additionally
there are no visual inspection methods that will detect SCC, so careful monitoring will not
insure that structural members are free from this effect. One Systems cannot recommend
the use of stainless steel wire ropes for suspension because of the issues discussed above.
Alternate structural materials, such as aluminum or plated steels, can also suffer from
chloramine attack and other corrosion mechanisms. Fortunately, there are several grades of
stainless steels that are extremely resistance to Chloride SCC. Super austenitic stainless