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TETRA radios for use in explosive risk areas

Our coverage of TETRA devices continues with a look at those that meet the needs of users who have to work in areas where ignition sources of any kind cannot be allowed. Even this requirement is well catered for, as Richard Martin discovers

From the fuel in our cars to the food on our plates,
we give very little thought to how complicated, difficult or even dangerous the processes might be behind our daily necessities. Mark La Pensee, head of TETRA Subscribers, Product Management at Motorola Solutions, says: “The reality is that many of the goods we regularly use will have passed through a hazardous environment during their creation and this presents a considerable communications challenge for those securing raw materials and manufacturing products.”

La Pensee continues: “Understanding what constitutes a ‘hazardous environment’ is a critical consideration when meeting communications and operational requirements.

An environment is defined as potentially hazardous if three conditions are met: there is a fuel source — a gas, a vapour, or some sort of ignitable dust; oxygen; and an ignition source. The scale of modern production means that a wide range of industries generate dangerous working environments where correct controls and safety must be stringently applied. Many industrial facilities encompass large, complex environments and these require integrated communication systems to facilitate effective and safe operations. Hazardous environments demand highly reliable, easy to use and intrinsically safe communication equipment.”

The oil and gas industry is the most well-known example of where there is a risk of explosion. This industry has specific stages each with their own challenges such as exploration, extraction, refining, storage, transportation and retail operations. The potential risk to life and investment at all stages makes it imperative that all equipment used in danger areas cannot generate sparks which would ignite gasses or dust. This includes all types of communication equipment including TETRA radios and accessories. Other industries also require radios to work in danger areas, including some types of food manufacture, utilities, mining, ports, airports and fire services. These industries have been a growth area for TETRA as users recognise the security, resilience, and versatility of this technology.

Techniques used by manufacturers in the design of
TETRA ATEX radios include the encapsulation of the electronics inside the radio, and care in the design of external electrical connections and materials which resist the build-up of static electricity.

To ensure there is no risk in service, electrical equipment
is thoroughly tested to predefined standards. There are
several bodies which define the standards for testing and, once certified, the products are labelled with the standards that they meet. In North America, the Factory Mutual
(FM) research corporation certifies radios, and Underwriters Laboratories (UL) certifies mobile phones. In Canada, the Canadian Standards Association certifies radios; and in the European Union, ATEX certification applies. In other regions of the world, the IECEx standards are used. These agencies engage in harmonisation activities so that equipment can

be exported between regions without extensive retesting.
The ATEX standard can be broken down into specifics such as the environment and testing regimes; the gas and dust classifications are shown in the table below. Radios will be marked with the standards above to which they have been tested. For example, the Hytera PT790 Ex radio meets the following explosive protection: gas: II 1G Ex ia IIC T4; dust: II 1D Ex ia IIIC T120oC IP6x; mine: I M1 Ex ia.


There are common features adopted by most manufacturers of ATEX radios. Man-down features such as tilt or inactivity sensing are used to alert controllers to a problem with a lone worker; this could be vital to prevent loss of life and dangers
if processes or equipment are left unattended. When using accessories with cables, the users risk becoming entangled
on machinery in confined spaces — Bluetooth connection can eliminate the use of cables. New battery technology is improving battery life, important if extended shifts are required during an incident. And high sensitivity in the
radio is important as they will often be working in
areas surrounded by metallic equipment and partly shielded from the base station or other users.

Users need to understand that accessories
need to be approved for use in risk areas. All manufacturers have approved accessories to
use with their radios, and using non-approved accessories could invalidate the certification and put plant and users at risk. Also, the users need to know which accessories can or cannot be connected or disconnected in the risk area — again this can become a problem if not understood.

The radios on offer from the main TETRA manufacturers are listed below.

Airbus_DS_THR9-Ex.jpegAirbus Defence
 and Space
Airbus offers the THR9 Ex
TETRA portable radio to use
where intrinsically safe radios are needed, certified to ATEX and IECEx for both gas and dust explosive risk areas. Usage examples include oil and gas, petrochemicals and steel
industries as well as rigs, airports and harbours.
The THR9 Ex (pictured right) also meets the needs of fire brigades when working in hazardous circumstances. The audio design of THR9 Ex offers clear sound and excellent audibility even in noisy environments.

It has a large and 
bright colour display to show critical information at a glance.
 It also enables use of applications such as positioning, images, reporting and searching for information in databases. Bluetooth wireless technology, combined with Ex-certified accessories, frees users from using wires. To keep the radio always powered and working, the battery and accessories of the THR9 Ex
can be changed inside the gas explosive area. The radio shares the multiple satellite capability of the TH9 (GPS, Glonass, BeiDou or Galileo), giving faster time to fix, and more accurate and reliable location information. The Lifeguard solution (man-down alarm), ‘Where are you?’ lone worker feature and night-vision screen provide extra safety to users.

The following frequency bands are supported: 330-360, 380-430 and 450-470MHz. A full set of TETRA features are supported including group, trunked and direct modes, type 1A repeater, call-out and security. TETRA SIM support means subscriber information can be moved easily between handsets.

Hytera has launched the PT790 Ex (pictured right), which is the first TETRA handheld certified to “ia” explosive gas and dust environments. This is the highest intrinsic safety rating and it means that
it can be used in areas where hazardous gas and dust is permanently present. In terms of physical environments it is rated to IP67 and MIL-STD-810 F/G standards. Man-down features are normal in intrinsically safe radios and the PT790 Ex has a sensor and timer to trigger alarms; location is sent using the standardised ETSI LIP format. The radio can operate on Direct Mode (DMO), interconnect to DMO repeaters, as well as link to a call-out application in the control room for resource management or paging purposes.
Hytera has again used its proven and user-friendly two-control knob design. Attention has been paid to a number
of factors such as possible discharges from protruding screws, which are countersunk to avoid contact with the ground. The sides and back of the radio are an anti-slip material useful in oily or dusty environments. The LCD screen can resist impacts even from a 1kg weight. To conform to the ATEX “ia” certification, the PT790 Ex has to survive ingress, drop and impact testing even after a 27-day-long “cook and freeze” test process.

The battery is secured to the radio by a new design of catch: a movement along three axis is mandated for the “ia” approval level, to ensure it will not become detached even if the radio
is dropped. Usual battery endurance is typically 14 hours.
The radio is compatible with the current firmware releases
and carries the same firmware as the Z1p and PT580H Plus series of products. It comes with features such as configurable User Alerts, Remote Control via Status and/or SDS functions, workflow management and Over The Air Programming. The telemetry request function is compatible with the MT680 Plus telemetry interface.

MTP8500Ex_Three-Quarter_Right.jpgMotorola Solutions
Motorola Solutions has designed the MTP8000Ex Series radios to incorporate advances in technology and also the findings of research into end-users and their roles. First, a T-Bar form factor has been adopted, making it easier to hold the radio

in gloved hands and reducing fatigue for the operator. When the radio is worn on a belt, the operator can easily see the
new top-mounted display when selecting talk groups or other functions. A key safety factor is an LED coverage indicator at the base of the antenna, which can easily be seen from above
as well as from the front or rear of the unit. This prevents users from being lulled into a false sense of security in areas with poor reception. The radio has also been designed to operate in areas of low signal strength to ensure the best possible coverage.

Easy-to-find controls such as the tactile PTT button add
to the user-friendliness of the radio. The exaggerated control knob has been made larger and easier to hold and use, and
the emergency button has also been enlarged and improved and placed beside the antenna so it is easy to find. Users who need to identify a radio with a marker risk compromising
the ATEX certification, so a simple but innovative nameplate has been added which means the MTP8000Ex can be easily labelled while retaining its certification. The radio also has a 16-hour battery life so that it can easily last an extended shift or emergency situation, as well as integrated Bluetooth.

The MTP8000Ex Series uses the Slimport design to
provide good audio performance. This is important in noisy industrial environments. Accessories are also an important factor in ensuring effective communication in these difficult situations, and Motorola provides a range of both wired and secure Bluetooth accessories including headsets and other audio devices, as well as the new ATEX Active Noise Cancelling RSM, which has both a Nexus and 3.5mm connector.

Sepura’s STP8X series is rated to the V6 version of the IECEx/ ATEX standard and carries an IP67 environmental protection rating — continuing to work after submersion in up to 1m
of water for up to 30 minutes, while also exceeding tests for working in extreme temperatures.

The terminals have been designed to provide unrivalled audio clarity, while a large screen visible in sunlight enhances safety for workers in hazardous environments. Long battery life and features such as Man-Down, local alarm and over-the-air alerting, plus Bluetooth and GPS functionality, further support lone workers and efficient working practices, while helping to ensure that procedures are properly adhered to. Available in
full and partial keyboard versions, the STP8X series has a full range of TETRA functions such as encryption and voice and data services, with additional features specifically needed for ATEX environments. Special attention has been given to audio performance with the hardware and software design, so that the radios will work effectively in noisy environments.

The large high-resolution screen allows full images to be seen in either landscape or portrait through a twist and zoom function, while the IMAGE application allows for the instant sharing of pictures, diagrams and other critical visual and contextual text information from the control room to field users. Other applications such as job allocation or database look-ups are enabled using WAP or SDS technologies.

STP8X_Gloved_Hand_.jpgWith a lithium ion battery, the STP8X (pictured right) can be used throughout a long shift without the need to change the battery. For convenience and user safety, Sepura-approved Nexus- connected accessories can be attached or removed from the Sepura STP8X RSM, with a large button PTT for when the user remains in a hazardous working area. In addition, there is a Bluetooth option allowing use with the latest wireless hazardous area certified accessories.

While critical voice communication is the primary function for these devices, Sepura offers additional applications, such as send/receive email, text messages and images, and integration of corporate data applications and services.

Leonardo (formerly Selex ES)
Selex ES has become Leonardo, it has the Puma T3 ATEX available for users. This is a multimode portable to meet the ATEX standards. Expect an update in the next few months as an ATEX version of the new T4 family is planned.

With TETRA increasingly used in oil and gas and other industrial applications, intrinsically safe radio is vital for use in explosion risk areas. All of the major manufacturers have or are bringing new ATEX TETRA radios to the market, combining innovations from their wider range of radios with the features needed by users in these risk situations. Improved coverage, audio and usability contribute to increased safety, which is of paramount importance for these industries.


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  1. 1
    Paul Spresser said...
    Mar 10th, 2017

    The Puma T3 is ATEX certified. However, its accessories are covered by a completely separate ATEX certification.

    I am after a copy of this ATEX EC Type Examination Certificate for our records.

    Number is: TUV 04 ATEX 2380X. While there is an image of page one of this on some datasheets, I need a copy of the entire certificate for legal reasons.


    Paul Spresser