Protupožarna crpna grupa NFPA

What is NFPA?
The National Fire Protection Association (NFPA), founded in 1896 in the United States, is widely accepted worldwide for its publications, programs and standards on fire and occupational safety. Training based on these standards improves practical application on projects.

What is NFPA 20?
NFPA 20 (Standard for the Installation of Centrifugal Fire Pumps) defines specifications, performance and installation rules for fire pumps, pump sets, motor control systems and the ancillary components that must be used.

Desan Engineering isporučuje protupožarne crpne grupe izrađene prema zahtjevima NFPA 20 za stacionarne sustave.

Istaknuto

• Separate controller for each pump
• Shut-off pressure not exceeding 1.4× rated pressure
• At 1.5× rated flow, pressure not less than 0.65× rated pressure
• Suction pipe velocities below 4.57 m/s (15 ft/s)
• Bearings with minimum 5,000-hour service life
• Bronze impeller; shaft AISI 316 or AISI 304; casing GG-25 cast iron
• Sealing with five-ring soft packing in series production
• Electric motor service factor not exceeding 1.15
• Prirubnice DIN 2533 / PN 16 (usis i tlačna strana obično TS EN 1092-2 / PN 16 na horizontalnim crpkama s aksijalnim usisom)

End-suction centrifugal fire pump set
Fire groups are commonly built on horizontal end-suction centrifugal hydraulics: single-stage, volute casing, closed impeller, coupling drive between motor and pump shaft. Soft packing is standard; mechanical seal can be supplied on request. Back-pull-out style access allows seal, shaft, bearings and impeller service without removing the volute from the piping. Rotation is counter-clockwise from the suction side; bearing housing is externally lubricated with an oil sight glass.

Electric motor driven fire pump sets
For maintenance, it is important that the pump can be serviced without full system dismantling. A jockey (leak) pump handles minor system leaks before the main pump starts, avoiding unnecessary main-pump cycles. Where mains power fails and a generator does not start, a diesel-driven fire pump can back up the electric set. Pressure switches support backup sequencing between units. Gate valves are preferred on the suction line; vacuum and pressure gauges monitor suction and discharge. Cooling-related valves on the set are kept closed in normal fire-pump duty. Multi-pump arrangements are typically designed for 100% redundancy so another unit can take over on failure. The fire suppression installation should resist horizontal seismic loads up to 0.5× its weight.

Diesel engine driven fire pump sets
In fire prevention systems, pumps are often used with 100% redundancy, and many sets are diesel-engine driven. NFPA 20 determines when an engine-driven pump is required. For electric pumps, relief-valve setting at shut-off is typically 1.21× shut-off head, with the valve on the discharge side. Desan Engineering uses spring-loaded relief valves in fire suppression packages.