Attack, blast and gas protection

Some protected spaces must resist attack, blast and airborne hazards together. Gas-tight doors with blast valves seal a room against pressure waves and contaminated air while keeping ventilation working. Specifiers set the attack, blast and airtightness ratings together, then match them to one tested construction.

• Gas-tight doorsSealed against airborne hazards
• Blast valvesVentilation that closes under pressure
• ISO 16933 and EN 13123Blast standards for glazing and doors
• Combined ratingsAttack, blast and gas in one assembly

What is attack, blast and gas protection

Attack, blast and gas protection is the set of measures that keeps a protected space usable when the outside turns hostile. Gas-tight doors seal the room against airborne hazards. Blast valves let ventilation work normally and slam shut when a pressure wave arrives. Forced entry ratings keep the doors resistant to attack. Together they form one system within our shielding range, for shelters, control rooms and protected spaces.

The combination matters because the threats arrive together: a blast that breaks ventilation open defeats the gas seal, and a gas-tight door that fails under pressure is no protection at all. Each element is specified against its own standard, and the assembly is only as strong as the weakest one.

The doors are sized for the room’s use, from personnel doors to large equipment openings, and each one is specified against the same combined threat set.

Which rating do you need for attack, blast and gas protection

Name each threat, then ask for test evidence against the matching standard. Gas-tightness is specified as a leakage rate agreed with the consultant, since no single product standard covers it.

Our blast ratings guide explains the EXV classes and hazard ratings in full.

How attack, blast and gas protection works

The door is a heavy steel leaf with compression seals around all four sides and multi-point locking that pulls it tight against the frame. Under blast pressure the leaf and frame work as one, and the seals keep the room gas-tight once the pressure passes. The frame is anchored to the structure to carry the blast load.

Ventilation runs through blast valves: louvred units whose blades stay open for normal airflow and close automatically under blast pressure, then reopen afterwards. The valves are sized with the ventilation design so the room keeps its air changes without oversizing the openings.

Ventilation is the weak point. A sealed room still needs air. Blast valves keep ventilation working day to day and close automatically under blast pressure, so size them with the ventilation design.

Combining with other ratings

Protected spaces usually sit inside a wider protected building. Blast resistant doors guard the approaches, blast resistant windows protect other openings in the envelope, and security doors rated to LPS 1175 handle forced entry at secondary entrances. Where fire separation is also required, fire rated steel doors complete the set.

Where attack, blast and gas protection is used

Government and defence sites protect command spaces, shelters and critical rooms. Utilities and energy operators shield control rooms that must stay staffed through incidents. Data centres use protected spaces for the staff and systems that keep services running.

What affects the cost and lead time of attack, blast and gas protection

Door sizes and the number of valves set the base scope. Combined ratings add engineering: a door that is gas-tight, blast rated and attack rated needs each performance proven. The ventilation design must be coordinated with the valve selection, and the structural openings must suit the frame anchorage. Testing and documentation for multiple ratings extend the programme. No prices are given here because every protected space differs.

How to specify attack, blast and gas protection

1. Define the threats. Blast, attack and airborne hazards for the space.
2. Size the openings. Fix door sizes and ventilation rates.
3. Choose the ratings. Name the blast, attack and leakage targets.
4. Coordinate ventilation. Select valves with the ventilation design.
5. Install and seal. Anchor frames and commission the seals.
6. Test and verify. Prove each rating with testing and surveys.

Attack, blast and gas protection FAQs