ZERO Drop Seal, Mortice, 355A - 355AA

355A AUTOMATIC DROPSEAL   

Need a fire and smoke-rated automatic mortice dropseal? The 355A mortice fix dropseal has achieved the high-performing BS EN 1634-3 smoke rating for cold smoke seals on steel doors. The 355A dropseal is also fire-rated for steel doors with up to 180 minutes of fire integrity to BS EN 1634-1:2014, making it the ideal addition to any steel fire door.   

ZEROplus dropseals have been tested to five million cycles and are also available as surface mounted (for retrofit). The 355A is available in stock sizes from 305mm to 1524mm in 152mm increments and may be cut down by up to 152mm (less for sizes under 762mm) from the non-operating end to suit exact door widths. Units are not handed (except 321AA, 323A and 354A) and operate from one end only so they can be used on pairs of doors.  

HOW DO ZEROPLUS DROPSEALS WORK? 

Fitted to the bottom of the door, ZEROplus dropseals automatically drop down each time the door is closed (adjustable drop up to 25.4mm on some patterns). The mechanical unit requires no electrical power to operate and works on a hinge-side plunger with a flat spring mechanism that drops the neoprene gasket in a scissor-like motion for a tight seal without any drag, even on an uneven floor. As the neoprene seal compresses, it forms a tight, secure bond against the threshold or floor. The door seal retracts automatically when the door is opened.  

Special-purpose dropseals are also available with light springing for wheelchair users, with lead lining for X-ray doors and a carbon-filled silicone rubber gasket to combat electromagnetic/radio frequency interference. These units ensure an effective seal at the bottom of the door against air and smoke filtration or penetration by sound, light, flames, toxic gases, electromagnetic and radio interference or X-rays. Combined with other ZEROplus frame seals, they form a total door kit.  

All ZEROplus automatic door bottoms function the same way. The mechanism causes the insert seal to activate on the hinge side first, preventing the seal from dragging along the floor or threshold while the door is being closed to avoid door hang-up or closing delay.  

355A AUTOMATIC DROPSEALS 

- Adjustable drop to 12.7mm 

- Mortice pattern  

- BS EN 1634-3 smoke rating for steel doors   

- Prevents the passage of toxic smoke  

- BS EN 1634-1:2014 fire rating for steel doors   

- Up to 180 minutes of fire integrity on steel doors  

- Units can be trimmed on-site  

- Tested to 5 million cycles  

- Suitable for double doors  

- UL Listed in USA, File GVY1.R18465  

- UK Assessments to BS 476: Part 22: 1987 and EN 1634-1: 2000. WF Report No. 187914 Issue 4, 347177 and UL UK File NC26268. Copies available upon request  

TYPICAL BUILDINGS REQUIRING DROPSEALS  

Entrances: particularly in areas of inclusive design where thresholds are not allowed.  

Entertainment: cinemas (keeping sound out), nightclubs (keeping sound in), theatres, stadiums 

Broadcasting: TV and radio companies, recording studios 

Travel: airports, railways, ferry terminals 

Industrial: oil rigs, turbine rooms, plant rooms, factory offices 

Medical: doctors' surgeries, health centres, hospitals, consulting rooms 

Business: offices, meeting/conference rooms, computer rooms 

Education: university/college lecture theatres, research facilities, music rooms 

Public: libraries  

Interview: police stations, magistrates' courts, banks, building societies, rooms for drink and drug rehabilitation, legal practices, probation offices 

Research: laboratories, dark rooms  

Leisure: hotel bedrooms, conference facilities