Heavy Duty Door Closer for Steel Doors

A steel door is heavy. 80-150kg. A steel door has vibration. When you close it, the whole door shakes. A steel door has torsion. The door twists a little as it moves. These three things kill normal closers.

This heavy duty door closer for steel doors is made for steel. The size is 4 or 5. Size 4 for doors 85-120kg. Size 5 for doors 120-150kg. The arm is 5.0mm thick steel plate. Normal heavy duty closers have 3.5-4.0mm arms. The twisting force of a steel door will bend a 4.0mm arm in 3-5 years. A 5.0mm arm has 2 times the strength. Strength goes up with the square of thickness.

We use M6 high strength bolts. Not self-tapping screws. A self-tapping screw into a steel door will not hold. It will come loose in months. You must drill a hole. Tap threads. Then use the M6 bolt with a spring washer to stop loosening. We include the bolts.

The arm gap is very small. 0.5mm or less. No wobble. We tested this heavy duty door closer for steel doors for vibration. We cycled the door 100,000 times at 1 cycle per second. The arm gap grew to 0.8mm. Still within spec. A normal closer would have a gap of 1.5mm at 30,000 cycles. The door would wobble and make noise.

Steel doors put high pressure on the hydraulic system. The piston and cylinder gap is 0.02mm or less. That is a very tight fit. High pressure oil cannot leak past. The door closes at the same speed every time. No slow closing because of internal leaks.

This heavy duty door closer for steel doors is for steel fire doors, steel entry doors, subway station doors, industrial factory doors, and military base doors. The warranty is 3 years for steel door use.