Facility Improvements/Hardware Additions
Alternatives to the Current Fire System
Various alternatives to a wet pipe sprinkler system exist when dealing with fire suppression. Among these are gaseous fire suppression methods, including carbon dioxide and nitrogen based agents, along with foam and chemical alternatives. The Oak Street Facility does not wish the existing fire suppression system to be changed, but does wish for recommendations for future additions to the building. Foam and chemical alternatives were ruled out early on and not examined due to the detrimental effect they would have on the books and rare materials. These effects include irreversible damage to paper, removal and distortion of ink, and residual film deposits. The two main clean agent gas suppression systems that exist on the market today, Inergen and FM-200, were examined in detail to determine their suitability for the facility. In-rack sprinklers, a wet pipe system that is located in the shelves, was also examined.
FM-200 or HFC-227ea (heptaflouropropane), is a colorless odorless gas that inhibits the chain reaction of molecules during combustion to extinguish a fire. For Class A combustibles (such as paper), a design concentration of 7.0% FM-200 is used7. To determine FM-200’s feasibility for use at the facility, the amount required was calculated using the formula W = (V/S)*(C/(100-C)).
Where: W = weight of HFC-227ea
V = volume of the hazard protected (400,000 ft3 for one module)
S = Specific vapor volume of HFC-227ea = 1.885 + .0045(T) where T = temp in degrees F
S = 2.11 ft3/lb. when T = 50 degrees F
C = HFC-227ea concentration (7.0%)
Using this formula, the weight of FM-200 necessary was calculated to be 14, 269 pounds for one module of the facility. The largest storage container produced by Fike, the leading seller of FM-200, is a 1000 pound tank. Thus, 15 of their largest containers would be necessary for just half of the facility and due to the large amount of gas required, the team has eliminated FM-200 as a possible alternative to the current sprinkler system.
Inergen is a mixture of 52% nitrogen, 40% argon, and 8% carbon dioxide that stops combustion by reducing oxygen to a concentration of 12.5%. Because Inergen contains carbon dioxide, there is no risk to personnel due to a lower oxygen rate. The carbon dioxide increases a person’s respiration rate and the body’s ability to absorb oxygen, allowing for deeper breathing more rapidly to compensate for the lower oxygen level in the room. However, Inergen does not compress to a liquid, and the design concentrations required are 40-50%. With 400,000 ft3 of storage, each module would require nearly 200,000 ft3 of Inergen to be effective. Due to the infeasible amount of gas necessary for this facility, the team does not recommend the use of Inergen.
To comply with the National Fire Protection Agency Code, NFPA 13, in-rack sprinklers that replace a standard wet pipe system must be of a certain type. This type of sprinkler is similar to a regular wet system, except that it has pipes and sprinkler heads above each shelf. The sprinkler heads are shorter than standard heads, to allow extra clearance for materials stored on the shelf. This design option was ruled out by the team after assessing the risk for accidental discharge due to books or trays coming into contact with the sprinkler head. Nearly all (>95%) sprinkler discharges that occur when there is no fire are due to something physical impacting the sprinkler head and breaking the glass bulb that activates the flow.
Nitrogen as a Supplement to Fire Suppression System
The use of nitrogen as a supplement to the current wet pipe system was also examined by the team. In order to inhibit combustion, enough nitrogen would need to be added to the facility to reduce the oxygen levels to below 15% (displacing about 24,000 ft3 of oxygen for one module). Air Liquide, a leading supplier of clean gases, produces a standard tank size for industrial use that is 234 ft3, pressurized to 2265 psi (gauge). Using the ideal gas law to achieve the simple relationship p1V1 = p2V2, it is found that 234 ft3 would provide 35,334 ft3 of nitrogen gas when released into the standard atmospheric pressure of the facility. After consultation with chemistry graduates, it was determined that nitrogen displaces oxygen in approximately a 1:1 ratio by volume. A standard 234 ft3 tank provided by Air Liquide would provide enough nitrogen to displace 24,000 ft3 of oxygen.
When used in conjunction with the current wet pipe system, nitrogen would provide an effective means to control and extinguish a fire. Along with the nitrogen tanks and the pipe system connecting the tanks to each module, oxygen sensors would be required to ensure that oxygen levels remain within safe concentrations for facility personnel. In addition to this the HVAC system should be turned off when nitrogen is released to ensure that nitrogen remains in the facility.
Relocation of Critical Items: “Safe Zones”
As has been noted previously, high priority items are stored alongside general collection items, and an item’s status has no bearing on its placement in the facility. Because of the large volume of special collection materials already present (48,000 items), the Oak Street staff does not wish current items to be relocated, but recommendations for future special collections materials is desired. A practice followed by other library high density storage facilities (such as Stanford) is to dedicate a section within the facility to storing high priority items and the team has assessed “safe zones” within the shelving units. The NIST Fire Dynamic Simulator (discussed in 5.1.1) allowed the team to diagnose locations that receive little to no water damage from the sprinkler system. Due to the cool air (50° F), the material’s close packing, and the small (1”-2”) clearance between the materials and the shelf above it (which restricts air flow), fire has been ruled a low risk and low priority. Thus, special collection materials will be placed in locations that do not receive the highest water damage from the sprinkler system. Safe zones are recommended to be above the third row to avoid flood damage, either from the sprinklers or other sources, and to be below the 11th row so that trays can be manually retrieved by handcart or moveable stair ladder. In addition to these locations, it is recommended that safe zones be located in several aisles (i.e. front half of the 1, 2, and 3 aisles) rather than just one to minimize a disaster’s risk of affecting all high priority items.
There are no projections for future incoming high priority items, so the number of safe zones necessary for future additions was estimated using the existing number of high priority materials in module 1. The type of each shelf (height) was found for all current special collections (shown in Figure 6.1), and reserved positions correspond to these numbers. 240 total positions (locations) are recommended to be designated safe zones in future modules.
Water Damage Prevention
Techniques for preventing water from directly affecting the general collection (and safe zones in particular) were examined by the team, but are not recommended for several reasons. Methods to cover the books or shield them pose problems to the general operations of the facility and to the materials themselves. Awnings or a type of overhead protection of the shelves would restrict lift movement, as the Raymond lift used by the facility takes up the entire aisle. A simple covering, such as a tarp or similar material would interfere with normal loading and unloading of shelves, and would add to the risk of mold damage after a water event by trapping moisture and humidity, creating microclimates. Most importantly, should a fire event damage the facility, it is desirable that the safe zones (though located in areas that receive low water damage) still receive water to aid in fire suppression and mitigate damage to the materials.
Special Collection Tray Materials
Alternative high priority tray materials are being explored to house the materials. After water testing with IFSI using the Reliable K-22 sprinklers that are in the facility, it was found that the acid/chemical free cardboard used for special collections did not maintain structural integrity when exposed to water. Trays began to fail as soon as 15 minutes into testing. This included the face containing the tray’s barcode being removed from the rest of the tray. The general collection trays, however, which are made of standard cardboard, were still intact and able to be removed from the shelf upon completion of the test. The team recommends that alternatives be found to house these priority materials due to their high value, preferably plastic or a similar material that does not absorb water. If plastic were used, holes should be present along the bottom of each tray to allow for water drainage. Trays that maintain structural integrity while wet are critical to maintain inventory control because barcode loss results in unidentifiable materials. To help prevent the loss of intellectual control, it is also recommended that barcodes are placed on the back of the tray in addition to the front. This would greatly reduce the chance that a tray would lose its barcode due to water damage.
Raymond Lift Improvements
The current tires used on the Raymond lift are a hard polymer that allows the lift to operate in water. These tires can be replaced with a rubber based tread to provide further traction in the event of standing water. The team, however, has determined this to be unnecessary since the majority or all of the standing water following a disaster will be removed prior to recovery efforts taking place.
It is recommended that an additional battery be obtained for the recovery process because the lift’s current battery can operate for only 6 hours before needing to be charged. Having an additional battery on hand will prevent downtime and allow the other battery to be recharged while recovering. Raymond Corporation insures that a battery can be delivered overnight when needed due to their in stock availability. For this reason, purchasing a new battery is unnecessary; the facility would not utilize an extra battery during normal operation.
Maximizing the capacity on the Raymond lift is also recommended since doubling its capacity reduces recovery time by 2.42 hours (see 7.3 for details). The lift’s current design has room for expansion, and the team has estimated that anything more than twice the current capacity would be infeasible due to lack of space.
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