Where can I buy Pyrexx smoke alarms?
You can order Pyrexx smoke detectors from this website, we are the UK stockist.

How should the annual servicing of the PX-1 be carried out and is gas testing necessary?
DIN 14676 is the appropriate standard for this particular servicing: as per this standard, the smoke detector should be inspected according to the operating instructions to see if it is functioning correctly at least once a year. This involves a visual inspection to see if the smoke inlet is not blocked in any way and that the smoke detector is not damaged; defects in this regard are to be rectified immediately. A damaged smoke detector must be replaced with a new one immediately. At the same time the alarm must be checked. This simply involves pressing the test and stop button on the PX-1 and thereby setting off a test alarm. We recommend carrying out this check once a month. Test gas is not required for testing the alarm on the PX-1. If, for example, you live in a rented property, the owner/property management may have commissioned a service provider to carry out the inspection detailed above.

Is it possible to change the battery in the PX-1 or do you have to throw the smoke detector away when the battery is flat?
The PX-1 smoke detector is fitted with a lithium battery which has a lifetime of at least 12 years and this is completely adequate. The centrepiece of the smoke detector is the photo-optic system in the smoke chamber. This component in our smoke detector changes over the years through a completely normal ageing process. The electronics in our smoke detector are able to recalibrate over the 12 years to compensate for this change and keep the trigger threshold for the alarm almost constant. After 12 years, this is no longer possible. We recommend replacing the smoke detector with a new one. Added to this there is, of course, the collecting of dust in the smoke chamber. As you can see, changing the smoke detector's battery to extend its lifetime would be completely meaningless.

Where should a smoke detector be installed? And where not?
As the sense of smell is not active in people and animals when they are asleep, and because two to four breaths of toxic smoke can lead to severed brain damage or death, it is important that a smoke detector is installed in every bedroom on the ceiling and as far as is possible in the centre of the room. Furthermore, detectors should monitor escape routes, such as corridors and stair wells, and be placed every four to six meters. Additional protection can be offered by also installing smoke detectors in rooms which are not used as bedrooms or escape routes, such as living rooms and dining rooms. Smoke detectors should always be installed for every 25m² of floor space and the distance between the devices should, if possible, be less than 6m.

How does a smoke detector work?
Inside the smoke detector there is a smoke chamber which contains an infra-red diode which emits a permanent light, which usually does not hit the light-sensitive photocell. If smoke particles enter the measurement chamber, the light from the infra-red diode is reflected is such a way so that it hits the highly-sensitive photo element. The electronics behind the optical measurement process interprets this as a risk of a fire. An alarm is then triggered. Who would go for two years without cleaning their car windscreen? Martin Dohmeier from Pyrexx GmbH. Everyone knows the situation: a film of dirt which impedes vision builds up on the inside of the windscreen after a few weeks. In the same way, ambient gases such as nicotine and particles of grease build up on the light-sensitive measurement components in the smoke detector, which lead to a gradual deterioration of the device's performance. In the worst case, this can mean that the measurement electronics are already heavily impeded after around 18 months and the smoke detector reacts to a fire only with a long delay. The consequence is that people may be injured or even killed! A high quality smoke detector always sends out an alarm at the same level of smoke density, recognises its level of contamination and gives out an acoustic signal which indicates its state at an early stage before its function as a warning device is endangered through a build up of dirt. Despite such technology, checks still have to be carried out as part of a careful maintenance regime to determine whether the device is undamaged, that the electronics are intact and above all that the air inlets are free of foreign bodies.

How does a smoke detector react to cigarette smoke?
As long as a large quantity of cigarette smoke is not deliberately blown into the smoke detector from the immediate vicinity, then the device will not send out an alarm. We have intensively tested the sensitivity to cigarette smoke of the smoke detectors we use and have established that even when there are numerous smokers in a small room, the device seldom triggers an alarm.

What environmental influences can trigger an alarm in the smoke detector?
As smoke detectors measure the transparency of the surrounding air by means of a photocell, gases which are very dense can trigger an alarm from the device. With dense water vapour and vapour from cooking, roasting, baking and grilling an appropriately high concentration of such gases in the surrounding environment of the smoke detector can set off an alarm as a precaution. Building dust, spray mist from spray painting, insect and room scent sprays which get into the smoke detector can also trigger an alarm and also contaminate the device. In a few cases, it has been known for an alarm to be triggered due to a strong through-draft or great variance in temperature.