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MV & LV SERIES ENGINEERED DRY CHEMICAL FIRE EXTINGUISHING SYSTEM
OPERATION, DESIGN, & SERVICE MANUAL
REV C
Document # DOC324
Issued: April 26, 2018
Revised: March 22, 2022
UL FILE # EX27541
3.2.3 Total Flood - JSH Nozzles
Total flooding dry chemical systems are used to fill a volume with agent to protect any hazard within that
volume. Typical applications include hazardous storage containers and warehouses. Total flooding systems
require a fixed enclosure to be present around the hazard area to allow the system to build up the proper
concentration of agent within the hazard area.
3.2.3.1 Nozzle Orientation
e placement, arrangement, and selection of the Engineered Orifice JSH Discharge Nozzles for total flood
application should be evaluated based on the hazard configuration and the coverage of each nozzle.
e JSH-360 and JSH-180 Discharge Nozzles have been tested by Underwriters Laboratories, Inc. with
respect to the total flood protection of hazards incorporating unclosable openings not exceeding 2.25% of
the total hazard surface area. If hazards have openings in excess of 2.25% the openings can be protected with
inclusion of screening nozzles for unclosable openings up to 19% of the total hazard surface area.
As an alternative to the use of screening nozzles for the protection of total flooding applications that have
unclosable openings with areas in excess of 2.25 percent of the total enclosure surface area and not exceeding
5 percent, NFPA 17 requires that the protected hazard be compensated for by the use of supplemental dry
chemical in the proportion of not less than 0.5 lb/ft² (2.44 kg/m²) of unclosed opening, applied through
the regular distribution system. Where the unclosable openings have areas exceeding 5 percent of the
total enclosure surface area enclosure and not exceeding 15 percent, compensation shall be furnished by
additional dry chemical in the proportion of not less than 1 lb/ft² (4.88 kg/m²) of unclosed opening, applied
simultaneously by local application over the openings.
NOTE: When using the screening nozzles to protect unclosable openings up to and not exceeding 19% of
the total enclosure surface area, additional supplemental dry chemical is not required.
Both sidewall 180° and radial 360° nozzles must be located at or near the ceiling with the halfway point
between the two vertical orifice layers no more than 12 in (304.8 mm) below the ceiling. e maximum
height for a single tier of nozzles is 18 ft 4 in (5.588 m) from floor to ceiling. For ceiling heights greater than
18 ft 4 in (5.588 m), additional tiers may be installed so that the maximum distance between the floor and
lowest row does not exceed 18 ft 4 in (5.588 m) and the maximum distance between rows does not exceed
18 ft 4 in (5.588 m).
Section 3 System Design
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