NF551A422 551A422 ASCO 551 Series Pilot Operated High Flow Solenoid Valve

1. Product Name: NF551A422 551A422 ASCO 551 Series Pilot Operated High Flow Solenoid Valve

2. Products shopping guide

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3. In addition

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5. FEATURES

• The monostable spool valves in conformity with IEC 61508 Standard (2010 

route 2H version) have TÜV (551 series) and EXIDA (551-553 series) certified 

with integrity levels: SIL 2 for HFT = 0 / SIL 3 for HFT = 1

• The spool valves have threaded port connections and "NAMUR" style interface

• The same spool valve can be adapted for 3/2 NC or 5/2 function for controlling 

double-acting and single-acting actuators

• All the exhaust ports of this spool valve are connectable, providing better 

environmental protection, particularly recommended for sensitive areas such as 

clean rooms, and applications in the pharmaceutical and food processing sectors

• The valve offers environmental protection against the ingress of liquids, dusts or 

any other foreign matter (environmentally-protected construction)

• Can be externally piloted (external air pilot supply) to convert valve to zero 

minimum operation by flipping a gasket

• The solenoid valves satisfy all relevant EU Directives

6. GENERAL

Differential pressure   2 - 10,4 bar [1 bar = 100 kPa]

Flow (Qv at 6 bar)      1/4 = 700 l/min (ANR)

                                 1/2 = 3000 l/min

fluids                         air, inert gas, filtered

temperature range     - 25°C to + 60°C

seal materials             NBR (nitrile) + PUR (polyurethane)

7. MATERIALS IN CONTACT WITH FLUID

Ensure that the compatibility of the fluids in contact with the materials is verified

Body                                  Aluminium, black anodized

End cover (spring)              Glass-filled PA

Interface plates                  Glass-filled PA

Spool valve internal parts    Zamak, stainless steel, (POM), aluminium

Pilot internal parts              Refer to specific solenoid catalogue pages

Pilot end covers                  Aluminium

Core tube                           Stainless steel

Core and plugnut               Stainless steel

Core spring                         Stainless steel

Seals                                   NBR

Top disc                              PA

Disc holder                          POM

Cartridge (low power)          Welded, packless AISI 430

Seat                                     Brass

Seat insert                           POM

Shading coil                        Copper

Rider rings (low power)        PTFE (NF/WSNF solenoids only