ASCO 551 553 Solenoid Valves (Spool) 3/2 NC, ¼”-3/8”-1/2” Aluminium (Pilot or Air) – Hazardous Area Valve Ex mb, Ex e mb

ASCO 551 553 – Pilot Operated or Air Operated Spool Solenoid Valves For Hazardous Areas & Potentially Explosive Atmospheres
ASCO 551 553 hazardous area solenoid valves are pilot operated or air operated spool type valves suitable for hazardous areas installation with international classifications including ATEX, UL, CSA and other local approvals on request.
3/2 ” Way Solenoid Valve
NC – Normally Closed Valve
NO – Normally Open Valve
Via ASCO Numatics FASTSHIP and SAMEDAY Express Delivery Service we are able to deliver 2,000+ ASCO valves from stock direct to you.
T&D are an Authorised UK Distributor for ASCO Numatics, part of Emerson Industrial Automation.
ASCO 551 553 SOLENOID VALVES
- 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 3/2 NC have threaded port connections
- 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)
- Epoxy moulded coil for general service applications
- ASCO 551 553 solenoid valves satisfy all relevant EC Directives
Differential Pressure : 2 – 10, 4 bar [1 bar = 100kPA]
Flow (Qv at 6 bar): 1/4 = 860 l/min (ANR)
1/2 = 3800 l/min
Fluids | Temperature Range (TS) | Valve Seal Materials |
air, inert gas, filtered | -25°C to +60°C | NBR Nitrile + PUR Polyurethane |
ASCO 551-553 solenoid valves are available with NAMUR interface. NAMUR, translated from the German acronym to StandardiSation Association for Measurement and Control in Chemical Industries, is the specification for a standard interface between pneumatic actuators, solenoid valves and directional control valves.
ASCO 551 553 – valve FLUID CONTACT COMPATIBILITY
ASCO 551 553 Solenoid Valve | |
Body | Aluminium, black anodised |
Internal Parts | Stainless Steel |
End covers | Glass-filled PA |
Seals | NBR + PUR |
Core tube | Brass |
Core and plugnut | Stainless steel |
Shading coil | Copper |
ASCO 551 553 – valve ELECTRICAL CHARACTERISTICS
Valve Coil Insulation Class : F
Electrical Safety : IEC 335
Standard Valve Voltages : DC (=) 24V – 48V
AC (~) 24V – 48V – 115V – 230V/50Hz; other voltages and 60Hz are available on request
ASCO 551 553 – VALVE SPECIFICATIONS – Air operated
Pipe size | Orifice size | Flow coefficient kV | Operating pressure differential (bar) | Prefix option | ASCO Catalogue number | |||
(mm) | (m3/h) | (i/min) | Min | Max (PS) | ||||
air (*) | ||||||||
~ | = | |||||||
Air pilot operated – spring return (monostable) | ||||||||
1/4 | 6 | 0.75 | 12.5 | 2 | 10 | 10 | – | ASCO 551A105 |
1/2 | 13 | 3.15 | 52.5 | 2 | 10 | 10 | – | ASCO 553A105 |
Air pilot operated and return (bistable) | ||||||||
1/4 | 6 | 0.75 | 12.5 | 2 | 10 | – | ASCO 551A106 | |
1/2 | 13 | 3.15 | 52.5 | 2 | 10 | 10 | – | ASCO 553A106 |
ASCO 551 553 – VALVE SPECIFICATIONS – Pilot OPERATED
Pipe size | Orifice size | Flow coefficient kV | Operating pressure differential (bar) | Power level ~/= | ASCO Catalogue number | |||
(mm) | (m3/h) | (i/min) | Min | Max (PS) | ||||
air (*) | ||||||||
~ | = | |||||||
Solenoid air pilot operated – spring return (monostable) | ||||||||
1/4 | 6 | 0.75 | 12.5 | 2 | 10 | 10 | RP | ASCO 551A005 |
1/4 | 6 | 0.75 | 12.5 | 2 | 10 | 10 | RP | ASCO 551A005 20787 |
1/2 | 13 | 3.15 | 52.5 | 2 | 10 | 10 | RP-BP | ASCO 553A005 |
Solenoid air pilot operated and return (bistable) | ||||||||
1/4 | 6 | 0.75 | 12.5 | 2 | 10 | 10 | RP | ASCO 551A006 |
1/4 | 6 | 0.75 | 12.5 | 2 | 10 | 10 | RP | ASCO 551A006 20787 |
1/2 | 13 | 3.15 | 52.5 | 2 | 10 | 10 | RP-BP | ASCO 553A006 |
ASCO 551 553 – VALVE OPTIONS
- Other pipe threads are available on request
- EX mb (prefix “PV”) solenoid can be supplied with various cable lengths
- Installation/maintenance instructions are included with each valve
- ASCO 551 553 solenoid valves can be mounted in any position without affecting operation
- Do not connect the pressure supply to the exhaust port 3. The “environmentally-protected” construction is not adapted for a “distributing” function or use in NO function. Contact us for functions available in specific versions
- IEC 61508 Functional Safety (suffix SL)
- It is necessary to connect pipes or fittings to the exhaust ports to protect the internal parts of the valve if used outside or in harsh environments (dusts, liquids etc)
- Threaded pipe connection identifier is: 8 = NPT (ANSI 1.20.3); G = G (ISO 228/1)
ASCO SOLENOID VALVES – ATEX, IEC EX & NEMA hazardous area CERTIFIED

ASCO Solenoid Valves For Hazardous Area Oil, Gas & Petrochem Industries (ATEX & IECEx) – call T&D for sales, technical and specification support on all ASCO valves.
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Hazardous Area Certification
ATEX (Zone 1 Zone 2), IEC Ex, NEMA (Div 1 Div 2) & Explosion Protection
➡ Did you know? T&D supply ATEX hazardous area certified Analytic Gas Heated Hoses.
➡ Did you know? T&D distribute Hazardous Area Instrumentation Equipment as Approved Vendors to global oil and gas operators and their EPC’s.