Home Technology Intruder Test: Selectamark SelectaDNA

Intruder Test: Selectamark SelectaDNA

by Benchmark

Increasingly, end users are looking for solutions that not only inform the authorities of a crime in progress, but also empower them to take appropriate action when they are the victims of an incident. Systems that dispense forensic materials can link individuals to specific crime scenes, but do they add to the overall level of protection? Benchmark looked at the SelectaDNA system from Selectamark to see what it offers.

selectadnarating[dropcap]I[/dropcap]n recent times, the intruder alarm sector has upped its game with regards to the technologies it offers. When it comes to value for money, it’s hard to find any security technology that can beat electronic detection systems. However, such systems do have one small limitation, in that they rely on response, or at least the threat of response, to create a deterrent value.

With police services battling with budget cuts and increased overheads, strain is being placed on the first response service. End users are increasingly aware that some intruders can be in and out of a premises long before any first response is forthcoming. In some geographical locations, they are aware that the likelihood of the police arriving in a timely fashion is minimal, even if they do respond immediately.

The reality is that many users realise that the chances of the police apprehending the perpetrator, and then of securing a conviction, are small unless there is a way to link a criminal to a specific crime. The response has been a rise in demand for video surveillance systems for sites that wish to enhance the deterrent factor of their security solutions, but even that is not a perfect solution. Video surveillance does a very different job to an intruder detection solution, and it is these differences that mean the two technologies aren’t always interchangeable.

An alternative exists in the increased offering of forensic liquids and greases, such as SelectaDNA from Selectamark.

An aggressive approach
Crime trends have changed in recent times. Two factors which have driven this change are a better understanding of high quality security systems at higher risk sites, and a general move towards the cashless society. As higher risk sites become better protected, and carry less cash, the more traditional low risk sites are increasingly being targeted by criminals.

When this is coupled with a rise in crimes using violence or threats of violence, many businesses are reassessing the deterrent value of their security systems. Evidence shows that there is no greater deterrent than an increased likelihood of arrest and conviction. The banks, betting shop chains, cash in transit operations and other high profile targets have proved this, and their aggressive approach to gaining convictions is one that other businesses are turning to in order to better protect their staff and assets.

One of the key objectives for such an approach is the ability to positively link an individual to a specific site, and to a specific incident. Forensic sprays – such as SelectaDNA – can achieve this. The system automatically emits the spray in response to a detection, a panic button or other input. Every aerosol cannister contains a liquid with a unique composition. This is registered with the manufacturer, and following an event the cannister is retained as evidence. The particles will remain on a criminal’s clothing, hair and skin for weeks, thereby providing evidence that links them to the site and event where that specific cannister was discharged.

The particles are invisible to the human eye, but can be viewed under ultraviolet light.

The SelectaDNA system is, in a nutshell, a controller and spray head that dispenses the contents of an aerosol canister in response to an input. That input can come from an exiting intruder alarm system, a panic button or another source. For the user, the real value lies in the unique composition of the liquid, and the secure database that allows specific canisters to be linked to sites and activations.

The system is made up of two components: the control box and the spray head. Control boxes are available supporting two or four spray heads. Spray heads can be located up to 30 metres from the controller. There are three types of spray head: a flat unit, a curved unit or a slimline unit. These contain the canister, and should be linked to a PIR which instigates operation of the spray head when an intruder is in the ‘spray area’.

The control box is designed to link with most intruder alarm systems. The unit requires two sets of normally open contacts. The first is to signal when the intruder alarm system is set, the second to indicate it is in alarm. When both sets of contacts are closed (i.e. the system has been set and is in alarm) then the spray head will be activated by the connected PIR.

There is also an input for a panic button, allowing the unit to be activated during times when the system is unset. This allows use in cash-handling areas or locations where staff may be vulnerable.

The spray head includes a timer, allowing a shut-off time for the spray to be set. This can vary between 1 and 10 minutes, and should be used to ensure that anyone attending the scene in response to the alarm is not sprayed.

The timer can be disabled if required. It is worth noting that the timer is not designed to allow multiple uses of the canisters. Once an event has occurred, the canister needs to be removed and retained as evidence should an arrest occur.

The control box will support a battery for back-up power should the supply fail or be sabotaged during an intrusion.

For many applications, the most critical part of the installation will be a correct site survey. A balance needs to be struck between efficiency and budgetary implications, as the location of the spray heads is critical to the overall  success of the system.  If they are located in an area that might be avoided by a criminal, there is a chance that the results will not allow the identification of suspects.

Putting the deterrent effect to one side, the aim of the system is to enhance the chances of conviction. Therefore, it is vital to identify the location of assets that will be targeted. From this, the potential entry and egress points must be identified. Doorways are an obvious choice, as the criminal will have to pass through the portal, ensuring a smaller target area. They are also ideal for mounting the spray heads. The importance of a correct survey and consideration about the location of the spray heads is pivotal to the overall success of the SelectaDNA.

The first element is installing the control box. This is a simple task, and the PCB has plenty of room for cabling. The board is marked and the manual includes a clear wiring diagram too. The only real consideration is that the unit must be housed within 30 metres of all attached heads.

Other connections can then be made to link the unit with an alarm system, to allow the control box to report canister activations, and to enable an interface with a PA button. If the system is linked to an alarm system, it will not operate whilst the system is unset. However, operation via a PA button will occur whether the alarm system is set or unset. Connections are made with standard 8 core alarm cable.

The next task is to install the spray heads. Again, these are simple to fit and the PCB is clearly marked, which combined with the straightforward instructions makes the process painless. There is a timer for the activation period, set via a potentiometer, but this can be overridden if required.

The manual stresses on nearly every page that the DNA canister must not be inserted until the instructions tell you to do so. If you ignore that and end up wasting a canister, you have only yourself to blame.

The final part of the installation is to mount and connect the trigger PIRs to the spray heads. Our test equipment was supplied with two Request to Exit detectors for automatic doors. When selecting a PIR, remember that the activation must occur when the intruder is under the spray unit, and that activation must occur immediately.

Features such as pulse count have to be disabled, or an intruder may be able to exit without triggering the device.
Once this has been completed the system can be powered up and tested – without the DNA canisters fitted!

Testing is simple. Activate the panic button, and then trigger each PIR attached to a spray head. The LEDs will indicate operation. The next stage is to test the intruder output when unset, and when set. The former should have no effect, and the latter should allow the heads to be triggered via the PIRs.

Should you wish to test the actual spray heads, a canister of water can be obtained from the manufacturer.

The SelectaDNA system is an electronic device, but the system that operates the canisters is mechanical, so during testing you’ll have no doubt that the unit has activated. A solid clunk indicates that the element which pushes the spray nozzle in has operated!

There is also one aspect of the system that must be considered, more after activations than during the installation. If the spray head is not vertical, there is a reference mark on the canister that needs to be at its lowest point. If it is not, the spray time will be reduced.

When activated, the spray is emitted for around 1 minute, at first very vigorously, then with diminishing force. This underlines how vital it is to ensure the positioning of the detector is correct.

In essence, the SelectaDNA element is simple. It will be as reliable and effective as the alarm system to which it is connected, and more importantly to the PIR used to trigger it. If these external elements are working as specified, then there is no reason for the SelectaDNA unit to not work as specified. Despite that, the external elements must still be considered, because they are integral to the success or failure of the solution.

During our test the unit did what it was specified to do, and if installed correctly then the chances of a false activation are very small.

With everything considered, SelectaDNA is a cost-effective and easy to install forensic spray system that can be used in a wide range of applications. There aren’t any major concerns with the hardware, and the credibility of the system will predominantly come from the registration services offered by Selectamark themselves, and police attitudes to such systems.

SelectaDNA offers a very real benefit that intruder alarm systems alone cannot deliver, and as such it has to be recommended.

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