The S4 steel door system is the pinnacle of high-security performance, offering tested protection against forced entry, ballistics, explosions, fire, and smoke. Ideal for critical infrastructure, industrial settings, and any building requiring the highest certified resistance levels — all within a customisable design.
Certified forced entry resistance up to RC6 (DIN EN 1627–1630)
Bullet resistance up to FB7-NS (DIN EN 1522–1523)
Blast resistance up to EXR5 (2,750 kPa) and tested with 500 kg explosives
Fire and smoke protection up to T90/EI90 and S200
Award-winning design with individual finishes including bronze and timber
Door leaf thickness up to 165 mm with reinforced steel cladding
Sound insulation up to RW 50 dB and thermal insulation up to UD = 2.2 W/m²K
Supports access control, panic locks, and automation systems
Tested for long-life operation: 200,000 opening/closing cycles
Uncompromising protection. Flexible architectural integration.
The Series S4 by SYSTEM SÄLZER® is a steel security door built for the world’s most demanding security applications. Certified up to RC6, FB7-NS, and EXR5, this high-performance system is designed to withstand aggressive attacks, explosive blasts, fire exposure, and prolonged use in high-traffic areas.
Despite its robust specification, the S4 door is visually versatile — available in finishes such as stainless steel, timber cladding, and bronze. Its design excellence was recognised with the German Design Award, highlighting its rare combination of functionality and form.
Available in both inward and outward opening formats, and compatible with SYSTEM SÄLZER® facades and access systems, the S4 series is suitable for industrial plants, government buildings, and critical infrastructure. Custom glazing, louvers, fire-rated variants, and full automation capabilities ensure the door meets every specification — without compromise.
Highest tested protection levels, tailored for critical use cases
Certified to DIN EN 1627–1630 with resistance up to RC6. Includes robust multipoint vault locking system for RC5/RC6 doors. Glazing above P8B is required for compliance in these classes.
Tested according to DIN EN 1522–1523 up to FB7-NS. Glazing certified to BR7-NS (DIN EN 1063). Optional enhancements tested against .50 BMG and NATO Stanag 2280 C5.
Certified up to EXR5 (20 kg | 4 m), with tests performed using explosive charges up to 500 kg at 28 m. Achieves GSA 2 and ISO B hazard classifications.
Fire protection up to T90/EI90 tested to DIN EN 13501-2 and BS 476 (up to 150 minutes). Smoke resistance up to S200 (C5). Available in both single and double door formats.
Thermal performance up to UD = 2.2 W/m²K. Acoustic insulation up to RW 50 dB, making it suitable for environments requiring both security and sound control.
Lifecycle tested for 200,000 opening/closing cycles. Supports leaf weights up to 600 kg for swing doors, 1,000 kg for turn wing gates, and 5,000 kg for sliding gates.
Supports mechanical, electro-mechanical and motorised locking systems. Compatible with access control hardware such as card readers and biometrics. Panic exit configurations tested to DIN 179 and DIN 1125 up to RC5.
Door leaf thickness ranges from 72–165 mm. Galvanised steel cladding as standard, with optional cladding in timber, bronze, stainless steel or stone. Includes bullet-resistant thresholds and 3- or 4-sided sealing options.
We take pride in delivering exceptional glazing solutions and outstanding customer service. Here’s what some of our happy clients have to say about working with Minimal Frame Projects.