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September 1999: Central Sprinkler's New K-25 ESFR Sprinkler

The Central Sprinkler Co. of Lansdale, PA has designed a new ESFR sprinkler head with pressure requirements of up to 60% less than its ESFR predecessors. The new Ultra K-25 ESFR sprinkler head has already been accepted by Factory Mutual (FM). The pressure requirement for the old ESFR sprinkler heads (K-factor of 14) was 50 psi for 30 ft. buildings with 25 ft. high storage. The pressure required for the same storage arrangement using the Ultra K-25 can be reduced to 20 psi.

There are several advantages to the K-25 ESFR sprinkler as compared to the older K-14 ESFR sprinkler. They are as follows:

- The main advantage is the lower required pressure.

- It can eliminate the need for a pump and all of the associated pump expenses.

- The maximum deflector distance is 18 in. for the K-25 ESFR heads whereas the K-14 ESFR heads have a maximum deflector distance of 14 in.

- The K-25 ESFR heads can be used for buildings up to 45 ft. high with 40 ft. high storage, without the need for in-rack sprinklers. The K-14 ESFR heads require in-rack sprinklers in this situation.

- There is a 5 ft. incremental ceiling design criteria above 30 ft. This limits the amount of pressure required in a more user friendly manner and makes plans easier to design and review.

The remaining installation guidelines are essentially the same for both ESFR sprinklers. The technical data on the ULTRA K-25 ESFR sprinkler head is as follows:

Model: ULTRA K-25
Style: Pendent
Orifice Size: 0.93 in.
K-Factor: 25
Thread Size: 1 in. N.P.T.
Temp. Rating: 160ºF and 200ºF
Sensitivity: Quick Response
Approvals: FM

A Tentative Interim Amendment has been made in the 1998 edition of NFPA 231C to incorporate the design of the K-25 ESFR sprinkler head. Table 10-1.1 "Early Suppression Fast Response (ESFR) Sprinkler Data" allows the following design parameters:

Storage Arrangement

Commodities Protected

Maximum Storage Height (ft.)

Maximum Building Height (ft.)

K-Factor

Sprinkler Design Pressure (psi)

Single, double,
and multiple
row racks
(No open top
containers
or
solid
shelves)

Class I, II, III
and IV
commodities
and
cartoned
unexpanded
plastics
Encapsulated
or
unencapsulated

25

30

25

20

30

35

25

30

35

40

25

40

40

45

25

50

Note: No in-rack sprinklers are required for the above mentioned design arrangements.

For more information call technical services at (800) 523-6512 - Central Sprinkler Co. of Lansdale, PA.