Chubb Dorgard saves time and limits disruption. Unlike expensive traditional fire door holders, Dorgard is completely wire-free.

Chubb Dorgard is available in black, red or white.

Chubb Dorgard is an acoustically activated fire door release device designed to allow freedom of access around a busy workplace whilst protecting the building and its occupants against the dangers of fire.  Here we answer some of the common questions about the product.

frequently asked questions

Does Chubb Dorgard only operate at one fixed decibel level?

No. Chubb Dorgard is designed to listen for sounds in excess of 65 dB, which is the minimum sound level for fire alarms complying with BS 5839 (with sleeping risks at 75 dB).

Chubb Dorgard listens for the fire alarm and recognises a range of sound levels within the 65 dB to 80 dB range.

In order to ‘custom fit’ a Dorgard to a particular fire alarm system, the Chubb Dorgard can be adjusted to ensure that it operates to that alarm.

At a general noise level of 80dB (sound Level) Chubb Dorgard will release to all sounds. This facility has been built into the unit as a safety feature. Should the noise level in your premises exceed 80 dB it is unlikely that you would hear a 65 dB alarm above a noise level of 80 dB, and therefore Dorgard releases automatically.

Why does Chubb Dorgard not close immediately a fire alarm sounds?

Chubb Dorgard operates using battery power. It continuously checks the battery life and in order to preserve battery life, Dorgard only ‘listens’ once every four seconds, and it needs to ‘hearlisten’ a continuous sound for at least 10 seconds before it operates. The ‘delay’ in operation should not be more than 14 seconds, and, therefore, not a significant delay.

Other door hold open systems also have a built in delay, even when ‘wired in’ to the fire alarm system. This is to allow so-called intelligent systems to interrogate the detection system to confirm that there is an actual fire.

The ‘bottom line’ (or common-sense approach) that I take on this is that with Dorgard, it is better to have a slight delay, then the door actually shuts to do its job, rather than being held or propped open by some ‘illegal’ object that continues to hold the door open and defeats the object of the door, letting fire and products of combustion through. The other advantage of the ‘delay’ is that it gives any person within the physical ‘operating limits’ of the door a chance to hear the fire alarm and clear the door before it actually shuts.

Is Dorgard a fail-safe product?

The term fail safe can easily be misunderstood, as no product is truly fail safe. Dorgard, however is designed to ‘fail-to-safe’ when the batteries have reached a low voltage (pre-determined by Dorgard) or when the battery compartment is tampered with or opened. In these events the plunger will automatically be released and Dorgard will no longer work as a hold open device. In addition to this release (triggered by low battery power) a series of flashes will be emitted by the LED and an audible warning will be sounded by Dorgard every 17 minutes until the batteries are completely exhausted, removed or replaced with new ones. However, the batteries should never be left to get to this state and a proper fire routine within the premises should include not only regular fire alarm tests to see that both the fire alarm and Dorgard respond correctly but also to renew batteries at regular intervals so that the Dorgard is working at its optimum.A further safety feature of Dorgard is the unit self tests and releases the door every 7 days to ensure reliable operation.

Does Dorgard comply with a formal standard?

Yes. There has been some confusion regarding Dorgard’s compliance with the relevant British Standard. This confusion was cleared up some time ago and Dorgard has been tested and complies with the new and appropriate standard for low voltage hold-open devices which is BS EN 1155.

If a Dorgard operates on the sound of a fire alarm and the fire door closes, will that closed fire door restrict the sound from reaching other Dorgards?

The audibility of a fire alarm should be at the sound level specified in BS5839 throughout the building, with all doors (not just fire doors) closed. It should, therefore, not affect any person in the building hearing the fire alarm and should not stop the operation of the Dorgard. Where the level of sound does drop slightly and within performance limits, each Dorgard can be adjusted to take this into account.

Where should Dorgard be fitted?

Dorgard can be fitted to self-closing fire doors when there is a need within a specific building to hold these types of doors open to facilitate the movement and circulation of people around that building, and anywhere where the door is likely to be wedged open. The building must, of course, have a fire alarm and consideration on the use of Dorgard should be carried out by the employer through a risk assessment procedure.

There are some cases where the use of Dorgard may be inappropriate, eg on doors protecting a single staircase building, and doors giving direct access to rooms in a premises that have been risk assessed as high risk, eg. kitchens, boiler rooms, etc.

How can Dorgard fail-safe if there is a failure of the fire alarm system?

A reasoned argument on this question is that the vast majority of fire alarms have to have emergency/back-up power supplies, then, if there is a fault, the system should continue to operate. As a failure in the alarm system also causes a ‘warning’ sequence, then within the risk-assessment for the building and the fire-routine, there should be an instruction that when this occurs, all hold open devices on doors should be de-activated and not used until the fire alarm system is re-instated.

Supplied with each Dorgard is a yellow warning label (Do Not Use) that should be used to place over the unit when it has been de-activated, and should not be removed until the fire alarm fault is rectified.

Should there be a smoke detector sited on each side of the door to which a Dorgard is fitted?

This suggestion/recommendation, I believe, goes back to the days when hold open devices were first introduced and a 'belt and braces' approach was taken. The idea was that if the smoke source was immediately to one side of a detector then it could travel some distance, including through the open fire door before it was detected by the next spaced detector in the 'line'. Thus, unnecessary smoke logging of the whole corridor/area could be the result prior to the door closing. Modern research on smoke travel and buoyancy disprove this, and in some cases, smoke entering a corridor from a room of origin may not have sufficient buoyancy to flow at ceiling level. It is, therefore, better to have smoke detectors in adjacent rooms for the earliest detection of fire and sounding the alarm, and remember, it is the sound of the alarm that operates Dorgard.

Can Dorgard be used in sleeping risks premises?

Yes. One of the main advantages of Dorgard is that it can be used in these types of premises as a cost effective way of maintaining the functionality of the building without compromising the fire safety precautions within the building.

Because of the life risk issues in these types of premises, the same procedures apply when Dorgards are fitted as with any other hold open devices, ie during the day, there needs to be an uninterrupted flow of people throughout the premises and Dorgard allows this. In the evening, it is a normal procedure to close all the fire doors by releasing them from their hold open devices. This practice should be an integral part of the daily fire routine for the premises.

Supplied with Dorgard, and recommended for use by the installation guide, is a fire door sticker which states "Dorgard automatic fire door, Keep Clear, Close at night".

Can Dorgard be used in 'dead end' conditions?

It all depends upon the dead end conditions under consideration. In a risk-assessed approach, consideration has to be given to such factors as the length of the corridor, the use of the room(s) directly off the corridor and the fire safety management regime in place.

Dorgard could be used in these types of situations if the fire risk assessment showed that the life risk in the dead end was low, the dead end was constructed to approved standards/codes and that there was a logical reason for fitting Dorgard.

In simple terms, never say never! If a door or a number of doors are likely to be wedged open by 'illegal' objects, then the use of Dorgard should be seriously considered as part of the fire risk assessed solution to the building or certain parts of it, like dead ends.

Can Dorgard prevent door warping?

Door warping is caused when fire doors are held open for long periods. Doors propped open with wedges etc are highly susceptible to door warping as the doors can be 'Held' for many months at a time. The warping is a result of the door closer continually applying a closing force to the door whilst the wedge is continually applying the reverse force. A diagonal line of twist (warp) in the door is the result.

Installation of Dorgard would prevent door-warping. Dorgard self tests every 7 days to release, not only to ensure reliable operation of the Dorgard unit, but also to alleviate any stress in the fire door. This operation also allows the overhead door closer to cycle itself, preventing seizure.

Does Dorgard test itself?

Yes, every seven days, the electronics automatically run a self-test routine which tests every working part of the Dorgard for successful operation. This releases the plunger allowing the door to close. Should Dorgard detect a fault within itself, it will sound a warning tone. Please also see comments to question above.

Do we need to do a Fire Alarm Audibility test before Dorgard is fitted?

No, it is not necessary as Dorgard is an audio sensing device, and operates on the same principle as a 'Sound Level Meter'. Dorgard is adjustable (within certain limits) should it not initially respond to the fire alarm. If Dorgard still does not 'Hear' the fire alarm after adjustment is made then it is most likely that the fire alarm installed is not reaching the minimum prescribed sound level, required by the BS 5839 standard.

It can therefore be considered that installing Dorgard(s) has in this situation alerted the employer to the fact that the sound level of the alarm is not correct, and appropriately, remedial action of the alarm is required.

Under these circumstances Dorgard must be removed or rendered to a safe condition until the fire alarm 'Sound level' is rectified to the Sound Levels required by the Standard.

Should staff and employees be made aware of Dorgard when they have been fitted?

Yes, it is most important that all employees are informed of any new safety features that have been included in the fire engineering of a building and this includes Dorgard. It is important that everyone understands its use and operation and they should be included into the fire routine within a workplace.

Does Dorgard automatically release at night?

Yes, it has 3 timed options to trigger the night time release function. Prior to installation the installer selects a setting required by activating a switch on the Dorgard unit. Dorgard will then release at the pre-determined time each night and will not operate as a door retainer until the following morning, whereby Dorgard will automatically reset itself for its normal duties. To set the Dorgards internal clock the unit must be powered up at 12:00 hrs.

Have a question?  Contact us on info@chubb.co.uk